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  • 1. Ali, Sharafat
    et al.
    Ellison, Adam
    Luo, Jian
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Composition-structure-property relationships of transparent Ca-Al-Si-O-N oxynitride glasses: The roles of nitrogen and aluminum2023In: Journal of The American Ceramic Society, ISSN 0002-7820, E-ISSN 1551-2916, Vol. 106, no 3, p. 1748-1765Article in journal (Refereed)
    Abstract [en]

    We explore the formation and composition–structure–property correlations of transparent Ca–Al–Si–O–N glasses, which were prepared by a standard melt-quenching technique using AlN as the nitrogen source and incorporating up to 8 at.% of N. Their measured physical properties of density, molar volume, compactness, refractive index, and hardness—along with the Young, shear, and bulk elastic moduli—depended roughly linearly on the N content. These effects are attributed primarily to the improved glass-network cross-linking from N compared to O, rather than the formation of higher-coordination AlO5 and AlO6 groups, where 27Al magic-angle-spinning nuclear magnetic resonance experimentation revealed that aluminum is predominately present in tetrahedral coordination as AlO4 units. Yet, several physical properties, such as the refractive index along with the bulk, shear, and Young's elastic moduli, increase concomitantly with the Al content of the glass. We discuss the incompletely understood mechanical–property boosting role of Al as observed both herein and in previous reports on oxynitride glasses, moreover suggesting glass-composition domains that are likely to offer optimal mechanical properties. 

  • 2.
    Bonneau, Charlotte
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Sanchez-Smith, Rebeca
    Guo, Bing
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Zhang, Daliang
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Inge, Andrew Kentaro
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Open-Framework Germanate Built from the Hexagonal Packing of Rigid Cylinders2009In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 48, no 21, p. 9962-9964Article in journal (Refereed)
    Abstract [en]

    We present a novel open-framework oxide material constructed from Ge10(O,OH)28 (Ge10) oxide clusters prepared via a nonsurfactant route. The material shows two distinct pore windows of 9.43 and 4.65 Å and a low framework density structure of 12.7 Ge atoms per 1000 Å3. The topological study leads to the recognition of a newly observed trinodal 6,7-heterocoordinated net related to the 7-coordinated swh net. The structure displays large rigid cylinders showing features indicating a growth mechanism by hard-sphere packing of the inorganic moiety similar to that observed in mesoporous materials.

  • 3. Brinkmann, Andreas
    et al.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Central-transition double-quantum sideband NMR spectroscopy of half-integer quadrupolar nuclei: estimating internuclear distances and probing clusters within multi-spin networks2014In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 16, no 15, p. 7037-7050Article in journal (Refereed)
    Abstract [en]

    We introduce a strategy to estimate the size of clusters of recoupled homonuclear half-integer quadrupolar nuclei under magic-angle spinning (MAS) conditions, by combining double-quantum (2Q) sideband NMR experiments with an approximate numerical analysis based on the summation of all spin-pairs present over a given radius of the structure. The experiment relies solely on the evolution of homonuclear 2Q coherences (2QC) among the central-transitions (CT) of half-integer spins and is suitable for probing clusters in network structures, such as those encountered in large groups of oxide-based materials. Experimental B-11, Na-23 and Al-27 NMR results are presented on bis(catecholato)diboron, Na2SO4 and Al2O3, respectively; in each case, the growth of the spin-cluster size was monitored from a series of experiments that employed progressively lengthened 2QC excitation intervals. Our new approach is the first option for probing larger constellations of half-integer spins; it provides similar information as the multiple-quantum spin counting experiment, which is well-established for spin-1/2 applications but has hitherto not been demonstrated for half-integer spins undergoing MAS. We also discuss various options for determining the internuclear distance within a (nearly) isolated pair of half-integer spins by comparing the experimental 2Q sideband NMR spectra with results from numerical simulations involving various degrees of approximation.

  • 4. Brinkmann, Andreas
    et al.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Estimating internuclear distances between half-integer quadrupolar nuclei by central-transition double-quantum sideband NMR spectroscopy2011In: Canadian journal of chemistry (Print), ISSN 0008-4042, E-ISSN 1480-3291, Vol. 89, no 7, p. 892-899Article in journal (Refereed)
    Abstract [en]

    We demonstrate the estimation of homonuclear dipolar couplings, and thereby internuclear distances, between half-integer spin quadrupolar nuclei by central-transition (CT) double-quantum (2Q) sideband nuclear magnetic resonance (NMR) spectroscopy. It is shown that the rotor-encoded sideband amplitudes from CT 2Q coherences in the indirect dimension of the two-dimensional NMR spectrum are sensitive probes of the magnitude of the homonuclear dipolar coupling, but are significantly less affected by other NMR parameters such as the magnitudes and orientations of the electric field gradient tensors. Experimental results of employing the R2(2)(1)R2(2)(-1) recoupling sequence to the (11)B spin pair of bis(catecholato)diboron resulted in an estimation of the internuclear B-B distance as (169.6 +/- 3) pm, i.e., with a relative uncertainty of +/- 2%, and in excellent agreement with the distance of 167.8 pm determined by single-crystal X-ray diffraction.

  • 5. Dalou, Celia
    et al.
    Füri, Evelyn
    Deligny, Cécile
    Piani, Laurette
    Caumon, Marie-Camille
    Laumonier, Mickael
    Boulliung, Julien
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Redox control on nitrogen isotope fractionation during planetary core formation2019In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 116, no 29, p. 14485-14494Article in journal (Refereed)
    Abstract [en]

    The present-day nitrogen isotopic compositions of Earth's surficial (N-15-enriched) and deep reservoirs (N-15-depleted) differ significantly. This distribution can neither be explained by modern mantle degassing nor recycling via subduction zones. As the effect of planetary differentiation on the behavior of N isotopes is poorly understood, we experimentally determined N-isotopic fractionations during metal-silicate partitioning (analogous to planetary core formation) over a large range of oxygen fugacities (Delta IW -3.1 < logfO(2) <Delta IW -0.5, where Delta IW is the logarithmic difference between experimental oxygen fugacity [fO(2)] conditions and that imposed by the coexistence of iron and wustite) at 1 GPa and 1,400 degrees C. We developed an in situ analytical method to measure the N-elemental and -isotopic compositions of experimental run products composed of Fe-C-N metal alloys and basaltic melts. Our results show substantial N-isotopic fractionations between metal alloys and silicate glasses, i.e., from -257 +/- 22% to -49 +/- 1% over 3 log units of fO(2). These large fractionations under reduced conditions can be explained by the large difference between N bonding in metal alloys (Fe-N) and in silicate glasses (as molecular N-2 and NH complexes). We show that the delta N-15 value of the silicate mantle could have increased by similar to 20 parts per thousand during core formation due to N segregation into the core.

  • 6.
    Eden, Mattias
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Determination of absolute quadrupolar tensor orientations by double-quantum NMR on powders2009In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 470, no 4-6, p. 318-324Article in journal (Refereed)
    Abstract [en]

    We introduce a new nuclear magnetic resonance (NMR) approach for determining electric field gradient (‘quadrupolar’) tensor orientations directly from polycrystalline powders. It involves a homonuclear 2D experiment that correlates (two-spin) double-quantum and single-quantum coherences of half-integer quadrupolar spin nuclei undergoing magic-angle-spinning. The 2D NMR spectrum is sensitive both to the relative orientations between the correlated quadrupolar tensors and to their orientations relative to the dipolar vector of the spin-pair. A novel strategy to calculate 2D spectra from multi-spin systems is used to extract the tensor orientations. We demonstrate the method by estimating the three 23Na quadrupolar tensor orientations in Na2SO3

  • 7.
    Eden, Mattias
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Homonuclear dipolar recoupling of half-integer spin quadrupolar nuclei: techniques and applications2009In: Solid State Nuclear Magnetic Resonance, ISSN 0926-2040, E-ISSN 1527-3326, Vol. 36, no 1, p. 1-10Article in journal (Refereed)
    Abstract [en]

    We review recent advances in solid state NMR methodology for recovering homonuclear dipolar interactions among half-integer quadrupolar spins undergoing sample rotation. Existing dipolar recoupling techniques are contrasted, based on (i) the form of their associated dipolar Hamiltonian, (ii) the different experimental conditions necessitating their realization and (iii) their roles as components in multi-dimensional NMR correlation spectroscopy. Various types of structural information accessible from such solid state NMR experimentation is reviewed. Promises and limitations of methodologies targeting homonuclear dipolar couplings between half-integer spins under high-resolution conditions are discussed, with particular focus on the demands set for structural investigations of crystalline as well as structurally disordered (amorphous) inorganic network materials

  • 8.
    Eden, Mattias
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Lo, Andy
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Supercycled symmetry-based double-quantum dipolar recoupling of quadrupolar spins in MAS NMR2009In: Journal of Magnetic Resonance, Vol. 200, no 2, p. 267-279Article in journal (Refereed)
    Abstract [en]

    Using average Hamiltonian (AH) theory, we analyze recently introduced homonuclear dipolar recoupling pulse sequences for exciting central-transition double-quantum coherences (2QC) between half-integer spin quadrupolar nuclei undergoing magic-angle-spinning. Several previously observed differences among the recoupling schemes concerning their compensation to resonance offsets and radio-frequency (rf) inhomogeneity may qualitatively be rationalized by an AH analysis up to third perturbation order, despite its omission of first-order quadrupolar interactions. General aspects of the engineering of 2Q-recoupling pulse sequences applicable to half-integer spins are discussed, emphasizing the improvements offered from a diversity of supercycles providing enhanced suppression of undesirable AH cross-terms between resonance offsets and rf amplitude errors.

  • 9.
    Edén, M
    Stockholm University.
    Quadrupolar coupling selective cross-polarization in solid state NMR2006In: Physical Chemistry Chemical Physics, Vol. 8, p. 1994-1999Article in journal (Refereed)
  • 10.
    Edén, M
    et al.
    Stockholm University.
    Zhou, D
    Yu, JH
    Improved double-quantum NMR correlation spectroscopy of dipolar-coupled quadrupolar spins2006In: Chemical Physics Letters, Vol. 431, p. 397-403Article in journal (Refereed)
  • 11.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Al-27 NMR Studies of Aluminosilicate Glasses2015In: Annual Reports on NMR Spectroscopy / [ed] Webb, GA, San Diego: Elsevier, 2015, Vol. 86, p. 237-331Chapter in book (Refereed)
    Abstract [en]

    Aluminosilicate glasses are of great geological and technological importance. Significant efforts have been spent for enhancing the insight into their structures, where magic-angle-spinning (MAS) NMR that exploits the spin-5/2 27Al as probe nucleus constitutes one widely utilized option. We review the application of basic 27Al NMR experimentation for studying primarily the short-range (less than or similar to 0.3 nm) structure of aluminosilicate glasses, emphasizing practical aspects of performing MAS and triple-quantum MAS NMR experiments, as well as options for data analysis to extract 27Al NMR parameters and quantifying AlOp populations. We illustrate the strengths and weaknesses of routine 27Al NMR for investigating aluminosilicate glasses, including its development over time. While parts of the text apply generally to MAS NMR targeting half-integer spins as structural probes in crystalline as well as amorphous materials, the focus remains on 27Al NMR applications to aluminosilicate glasses, whose basic structural features are outlined together with a survey of the most central research problems in the field. By providing both in-depth discussions about the building blocks of aluminosilicate glasses while assuming a modest background knowledge of the reader about MAS NMR and glass structure, we hope that the presentation will appeal to a broad audience, encompassing both experienced researchers in solid-state NMR or glass structures, as well as to beginners in either area.

  • 12.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Probing oxide-based glass structures by solid-state NMR: Opportunities and limitations2023In: Journal of magnetic resonance open, ISSN 2666-4410, Vol. 16-17, article id 100112Article in journal (Refereed)
    Abstract [en]

    This Primer critically reviews the possibilities and limitations of probing the short-range structure of an oxide-based glass by routine magic-angle spinning (MAS) or triple-quantum MAS (3QMAS) nuclear magnetic resonance (NMR) experiments. We briefly outline the structural features of oxide-based glasses and the basics of solid-state NMR. Besides suggesting guidelines for selecting favorable experimental conditions and important considerations for recording high-quality MAS NMR spectra amenable for subsequent analysis, we review options for extracting NMR observables and their distributions from spins-1/2 as well as half-integer spin quadrupolar nuclei. Considering that the isotropic chemical shift remains the primary probe of local structure by MAS NMR, we thoroughly review its dependence on the short-range oxide-based glass parameters from the viewpoint of a very simple and intuitive but qualitative model. The utility of deconvolutions of notably 29Si and 31P MAS NMR spectra are discussed critically. We also suggest alternative yet qualitative analysis options that are available whenever MAS NMR spectral deconvolutions are not warranted without additional information, which incidentally applies to a majority of modern multicomponent glasses.

  • 13.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Structure and formation of amorphous calcium phosphate and its role as surface layer of nanocrystalline apatite: Implications for bone mineralization2021In: Materialia, E-ISSN 2589-1529, Vol. 17, article id 101107Article in journal (Refereed)
    Abstract [en]

    We provide a critical review of the chemical composition and structure of synthetic and biogenic (bone/dentin mineral) nanocrystalline hydroxy-carbonate apatite (HCA). Such particles exhibit a core-shell organization, where an ordered HCA core is coated by a surface layer, whose nature is best captured by amorphous calcium phosphate (ACP), which is known to be a precursor phase of synthetic HCA, but whose role of bone/dentin mineralization has remained a most controversial subject. After reviewing the structure of each HCA and ACP component, as well as the most recent findings on their in vitro formation mechanisms, we examine the core-shell HCA organization further, with a focus on the disordered surface (shell ) domain. In most of recent literature, the surface portion is often referred to as the hydrated surface layer , but without identifying its shared chemical and structural features of (synthetic) ACP. Unfortunately, that missing surface-layer/ACP equivalence obscures that the surface layer at the synthetic/biogenic nanocrystallites may simply constitute a remnant of the ACP phase from which the ordered HCA core nucleated. Although many topics reviewed herein have been investigated for more than six decades, several remain unsettled and heavily debated. Notably, decades-old articles offer suggestions that have passed unnoticed by the younger generations of researchers; we contrast and discuss both the latest and early contributions of this field, as well as highlighting several unsettled topics that should be revisited to improve our understanding of the ACP and HCA structures and in vitro / in vivo formation mechanisms.

  • 14.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    The split network analysis for exploring composition-structure correlations in multi-component glasses: I. Rationalizing bioactivity-composition trends of bioglasses2011In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 357, no 6, p. 1595-1602Article in journal (Refereed)
    Abstract [en]

    We present a strategy, referred to as “split network” analysis, for assessing the average network polymerization (r(F)) and mean number of bridging oxygen (BO) atoms ( (N) over bar (F)(BO)) for each individual network former F in multi-component oxide-based glasses, primarily targeting those involving Al, B, P and Si. This requires a priori knowledge about the parameters (r(F), (N) over bar (F)(BO)) of all network builders, but one, whose values are deduced by the split network procedure. We illustrate split-network concepts for establishing composition/structure/bioactivity correlations in Na-Ca-Si-P-O glasses. The cooperating influences on the bioactivity from the average polymerization degree of the silicate network and the amounts of orthophosphate and sodium ions are discussed.

  • 15.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Two-dimensional MAS NMR correlation protocols involving double-quantum filtering of quadrupolar spin-pairs2010In: Journal of magnetic resonance, ISSN 1090-7807, E-ISSN 1096-0856, Vol. 204, no 1, p. 99-110Article in journal (Refereed)
    Abstract [en]

    Three two-dimensional (2D) NMR homonuclear correlation techniques invoking double-quantum (2Q) filtration of the central transitions of half-integer spins are evaluated numerically and experimentally. They correlate directly detected single-quantum (1Q) coherences in the t(2) domain with either of 1Q, two-spin 2Q or single-spin multiple-quantum coherence-evolutions in the indirect (t(1)) dimension. We employ experimental Na-23 and Al-22 NMR on sodium sulfite and the natural mineral sillimanite (SiAl2O5), in conjunction with simulated 2D spectra from pairs of dipolar-recoupled spins-3/2 and 5/2 at different external magnetic fields, to compare the correlation strategies from the viewpoints of 2D spectral resolution, signal sensitivity, implementational aspects and their relative merits for establishing internuclear proximities and quadrupolar tensor orientations.

  • 16.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Update on Al-27 NMR studies of aluminosilicate glasses2020In: Annual Reports on NMR Spectroscopy / [ed] Atta-ur-Rahman, London: Academic Press, 2020, 1, Vol. 101, p. 285-410Chapter in book (Refereed)
    Abstract [en]

    Aluminosilicate glasses and melts are of great geological and technological importance. Significant efforts have been spent for enhancing the insight into their structures. Here magic-angle-spinning (MAS) NMR that exploits the spin-5/2(27)Al as probe nucleus constitutes one widely utilized option. We review the application of Al-27 NMR experimentation to aluminosilicate glasses, emphasizing practical aspects of performing MAS and triple-quantum MAS NMR experiments, as well as options for data analysis to extract Al-27 NMR parameters and quantifying AlOp populations. Despite that parts of the text apply generally to MAS NMR targeting half-integer spins as structural probes in both crystalline and amorphous materials, the focus remains on Al-27 NMR applications to aluminosilicate glasses, whose basic structural features are outlined together with a survey of the most central research problems in the field. The current update of our previous article from 2015 [Eden, Annu. Rep. NMR Spectrosc. 86 (2015) 237-331] also reviews the principles of heteronuclear NMR experimentation and its applications to study both the short (less than or similar to 0.3 nm) and medium (approximate to 0.3-1 nm) range structure of aluminosilicate glasses. Moreover, the present article also extends our previous account by reviewing some of the most recent work in the area up to the beginning of year 2020, where several sections are significantly modified and expanded. The presentation is intended for a broad audience, encompassing both experienced researchers in solid-state NMR and/or glass structures, as well as to beginners in either area.

  • 17.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zeeman Truncation in NMR. I. The Role of Operator Commutation2015In: Concepts in magnetic resonance. Bridging education and research, ISSN 1546-6086, E-ISSN 1552-5023, Vol. 43, no 4, p. 91-108Article in journal (Refereed)
    Abstract [en]

    Hamiltonians are of pivotal importance for describing and analyzing NMR experiments. However, the exact spin Hamiltonian operators are in practice not utilized, but merely a simplified form referred to either as the secular, Zeeman-truncated, or high-field Hamiltonian. It results after accounting for the dominating role of the Zeeman interaction relative to all other, much smaller NMR interactions, such as chemical shifts, through-bond, or through-space spin-spin couplings. In this article and the following one, we introduce the Zeeman truncation process to newcomers to NMR by thoroughly reviewing the options available for reducing the full Hamiltonian of a spin interaction to its Zeeman-truncated counterpart. The present paper considers time-independent Hamiltonians, where we discuss the criteria for performing truncation, highlighting the role of operator commutation by a simple formalism that is equivalent to application of lowest-order static perturbation theory. The validity of the approximations are illustrated by examining the explicit matrix representations of the exact and Zeeman truncated Hamiltonians, considering the NMR interactions relevant for systems of interacting spin-1/2 nuclei.

  • 18.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zeeman Truncation in NMR. II. Time Averaging in the Rotating Frame2015In: Concepts in magnetic resonance. Bridging education and research, ISSN 1546-6086, E-ISSN 1552-5023, Vol. 43, no 4, p. 109-126Article in journal (Refereed)
    Abstract [en]

    The truncation of NMR interactions by the Zeeman Hamiltonian is here examined from a different perspective than that of our previous article [Concepts Magn. Reson., vol. 43A, pages 91-108 (2015)]: a Zeeman-truncated Hamiltonian is arranged by transforming the initially stationary operator of the NMR interaction into the rotating frame, followed by a time-averaging procedure over one Larmor period ( 2/0). We review the concept of an interaction frame, with focus on the rotating frame relevant for the Zeeman interaction, as well as the time-averaging procedure and the criteria for application of the resulting stationary Hamiltonian. A decisive advantage of this approach is its suitability for truncating time-dependent Hamiltonians, such as that of a radio-frequency (RF) field. Various options for reducing the time-dependent RF Hamiltonian into its stationary form are contrasted and thoroughly discussed. The role of Zeeman truncation is illustrated by examining the rotating-frame RF Hamiltonian associated with both on-resonance and off-resonance irradiation, where the time-independent operator character allows for applying the approximation strategies reviewed in our previous article.

  • 19.
    Edén, Mattias
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Sundberg, Peter
    Stålhandske, Christina
    The split network analysis for exploring composition-structure correlations in multi-component glasses: II. Multinuclear NMR studies of alumino-borosilicates and glass-wool fibers2011In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 357, no 6-7, p. 1587-1594Article in journal (Refereed)
    Abstract [en]

    The preceding part [M. Eden, J. Non.-Cryst. Solids, 357, (2011) 1595-1602] introduced the “split network” strategy for estimating the network polymerization degree (r(A)) and mean number of bridging oxygen (BO) atoms ((N) over bar (A)(BO)) for a network former A, given that these parameters are known for all other network builders in the multi-component oxide glass. However, as the detailed ordering of BO and non-bridging oxygen (NBO) species is often difficult to assess experimentally, we summarize some “rules of thumb” for predicting the coordination number and tendency to accept NBO ions for Al(3+), B(3+), Si(4+) and P(5+) cations: they are helpful in scenarios devoid of experimental data. Using the parameters r and (N) over bar (BO), we present expressions for the BO/NBO distributions among tetrahedrally coordinated cations, as predicted from the binary and random models. Multinuclear (11)B, (27)Al and (29)Si solid-state NMR is exploited to derive the split network representations of a set of Na-Ca-(Al)-(B)-Si-O glasses. These results are subsequently used to gain structural insight into two commercial glass-wool fibers that constitute alumino-borosilicate networks modified by Na(+), K(+), Ca(2+) and Mg(2+) ions.

  • 20.
    Gebauer, Denis
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Materials Chemistry.
    Gunawidjaja, Philips N.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Ko, J. Y. Peter
    Bacsik, Zoltan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Materials Chemistry.
    Aziz, Baroz
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Materials Chemistry.
    Liu, Lijia
    Hu, Yongfeng
    Bergström, Lennart
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Materials Chemistry.
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Sham, Tsun-Kong
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Materials Chemistry.
    Proto-Calcite and Proto-Vaterite in Amorphous Calcium Carbonates2010In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 49, no 47, p. 8889-8891Article in journal (Refereed)
    Abstract [en]

    Amorphous order: Amorphous calcium carbonates (ACC) have an intrinsic structure relating to the crystalline polymorphs of calcite and vaterite. The proto-crystalline structures of calcite and vaterite (pc-ACC and pv-ACC) are analyzed by NMR (see picture), IR, and EXAFS spectroscopy, which shows that the structuring of ACC relates to the underlying pH-dependent equilibria.

  • 21.
    Gunawidjaja, Philips N.
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Izquierdo-Barba, Isabel
    Mathew, Renny
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Jansson, Kjell
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Garcia, Ana
    Grins, Jekabs
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Arcos, Daniel
    Vallet-Regi, Maria
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Quantifying apatite formation and cation leaching from mesoporous bioactive glasses in vitro: a SEM, solid-state NMR and powder XRD study2012In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 22, no 15, p. 7214-7223Article in journal (Refereed)
    Abstract [en]

    By employing solid-state nuclear magnetic resonance (NMR) spectroscopy, powder X-ray diffraction (PXRD), and scanning electron microscopy coupled with energy-dispersive X-ray (EDX) spectroscopy, we compare the biomimetic growth of calcium hydroxyapatite (HA) from an ordered mesoporous bioactive glass (MBG) in simulated body fluid (SBF) and buffered water solutions. For the latter medium, we also examine the effects of using two different MBG concentrations. We evaluate the predicting powers of PXRD and P-31 NMR for directly quantifying the relative amounts of biomimetic amorphous calcium phosphate (ACP) and HA: we observe a very good agreement between the two analytical techniques. Thanks to their mesoporous channel system, fluids readily penetrate throughout sub-mm sized MBG grains, as evidenced by EDX. The latter revealed distinct element-mappings across the material after its exposure to SBF compared to water. Under our in vitro conditions involving relatively high MBG-loadings in the solutions, the HA formation reduces in SBF relative to buffered water, particularly for increasing MBG concentration. These features stem from a high [Ca2+]/[PO43-] ratio resulting in the fluid medium, which retards the HA crystallization by inducing a rapid ACP precipitation and an accompanying depletion of phosphate ions in the solution. This has bearings on the design of bioactivity comparisons of bioglasses exhibiting significantly different cation compositions.

  • 22.
    Gunawidjaja, Philips N.
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Lo, Andy Y.H.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Izquierdo-Barba, Isabel
    Garcia, Ana
    Arcos, Daniel
    Stevensson, Baltzar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Grins, Jekabs
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Vallet-Regi, Maria
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Biomimetic Apatite Mineralization Mechanisms of Mesoporous Bioactive Glasses as Probed by Multinuclear ³¹P, ²⁹Si, ²³Na and ¹³C Solid State NMR2010In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 114, no 45, p. 19345-19356Article in journal (Refereed)
    Abstract [en]

    An array of magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy experiments is applied to explore the surface reactions of a mesoporous bioactive glass (MBG) of composition Ca0.10Si0.85P0.04O1.90 when subjected to a simulated body fluid (SBF) for variable intervals. Powder X-ray diffraction and 31P NMR techniques are employed to quantitatively monitor the formation of an initially amorphous calcium phosphate surface layer and its subsequent crystallization into hydroxycarbonate apatite (HCA). Prior to the onset of HCA formation, 1H → 29Si cross-polarization (CP) NMR evidence dissolution of calcium ions; a slightly increased connectivity of the speciation of silicate ions is observed at the MBG surface over 1 week of SBF exposure. The incorporation of carbonate and sodium ions into the bioactive orthophosphate surface layer is explored by 1H → 13C CPMAS and 23Na NMR, respectively. We discuss similarities and distinctions in composition−bioactivity relationships established for traditional melt-prepared bioglasses compared to MBGs. The high bioactivity of phosphorus-bearing MBGs is rationalized to stem from an acceleration of their surface reactions due to presence of amorphous calcium orthophosphate clusters of the MBG pore wall.

  • 23.
    Gunawidjaja, Philips N.
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Mathew, Renny
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Lo, Andy Y. H.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Izquierdo-Barba, Isabel
    Garcia, Ana
    Arcos, Daniel
    Vallet-Regi, Maria
    Eden, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Local structures of mesoporous bioactive glasses and their surface alterations in vitro: inferences from solid-state nuclear magnetic resonance2012In: Philosophical Transactions. Series A: Mathematical, physical, and engineering science, ISSN 1364-503X, E-ISSN 1471-2962, Vol. 370, no 1963, p. 1376-1399Article in journal (Refereed)
    Abstract [en]

    We review the benefits of using Si-29 and H-1 magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy for probing the local structures of both bulk and surface portions of mesoporous bioactive glasses (MBGs) of the CaO-SiO2-(P2O5) system. These mesoporous materials exhibit an ordered pore arrangement, and are promising candidates for improved bone and tooth implants. We discuss experimental MAS NMR results from three MBGs displaying different Ca, Si and P contents: the Si-29 NMR spectra were recorded either directly by employing radio-frequency pulses to Si-29, or by magnetization transfers from neighbouring protons using cross polarization, thereby providing quantitative information about the silicate speciation present in the pore wall and at the MBG surface, respectively. The surface modifications were monitored for the three MBGs during their immersion in a simulated body fluid (SBF) for intervals between 30 min and one week. The results were formulated as a reaction sequence describing the interconversions between the distinct silicate species. We generally observed a depletion of Ca2+ ions at the MBG surface, and a minor condensation of the silicate-surface network over one week of SBF soaking.

  • 24.
    Guo, Hua
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Pujari-Palmer, Michael
    Yu, Yang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Stevensson, Baltzar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Engqvist, Håkan
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Quantitative phase analyses of biomedical pyrophosphate-bearing monetite and brushite cements by solid-state NMR and powder XRD2020In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 46, no 8, p. 11000-11012Article in journal (Refereed)
    Abstract [en]

    We present a comprehensive composition analysis of calcium phosphate cements (CPCs) incorporating increasing amounts of bioactive pyrophosphate species (up to 17 wt% P2O7). These cements comprise primarily poorly ordered monetite (CaHPO4) or brushite (CaHPO4 center dot 2H(2)O) and are investigated for enhanced osteoinductive bone/tooth implants. The specimens were characterized by magic-angle spinning (MAS) P-31 and H-1 nuclear magnetic resonance (NMR) spectroscopy along with powder X-ray diffraction (PXRD). P-31 MAS NMR was employed to quantify the major monetite/brushite constituents, the crystalline and amorphous pyrophosphates, as well as various minor orthophosphate by-products. The NMR-derived contents of the crystalline phases accorded well with those from Rietveld analyses of the corresponding PXRD data. The amounts of crystalline and amorphous pyrophosphate depended on the precise cement precursor mixture and preparation conditions, which together with their distinct structural roles may enable the design of cements with a tunable P2O74 - release into aqueous solutions.

  • 25.
    Hakeem, A. S.
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Daucé, R.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Leonova, E.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Edén, M.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Shen, Z.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Grins, J.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Esmaeilzadeh, S.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Silicate glasses with unprecedented high nitrogen and electropositive metal contents obtained by using metals as precursors2005In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 17, p. 2214-2216Article in journal (Refereed)
    Abstract [en]

     

     

  • 26.
    Hålenius, Ulf
    et al.
    Naturhistoriska riksmuseet.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Skogby, Henrik
    Naturhistoriska riksmuseet.
    Nazzareni, Sabrina
    Perugia University.
    Kristiansson, Per
    Lunds universitet.
    Resmark, Jeppa
    Lunds universitet.
    Coordination of Boron in Nominally Boron-Free Rock Forming Silicates: Evidence for Incorporation of BO3 groups in Clinopyroxene2010In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 74, p. 5672-5679Article in journal (Refereed)
    Abstract [en]

    To explore mechanisms of B-incorporation in common chain silicates we have investigated synthetic diopside samples produced under boron-saturated conditions by 11B and 29Si magic-angle spinning (MAS) NMR and single-crystal NRA, FTIR, EMP and XRD/SREF techniques. Our samples contain 0.14–0.65 wt.% B2O3. NMR reveals that B is predominantly present in trigonal coordination in the clinopyroxene structure. This observation is supported by vibrational bands characteristic for B–O stretching in BO3 groups in the range 1250–1400 cm−1 in polarised single crystal FTIR-spectra. Single crystal structure refinements suggest that boron replaces Si at the T site. Combined, these results suggest that boron replacement for Si at the T-site leads to disruption of one of the T–O bonds of the nominal clinopyroxene structure resulting in replacement of SiO4 tetrahedra by BO3 groups. Our results show that high concentrations of boron can be incorporated in the nominally boron-free diopside. Elevated B-concentrations in the present calcic clinopyroxenes are accompanied by modifications of the diopside crystal structure involving the breaking of one T–O bond and simultaneous formation of vacancies at the octahedral M2 site. These structural modifications destabilize the structure and constitute thereby limiting factors for incorporating higher boron concentrations in diopside.

     

     

  • 27.
    Iftekhar, Shahriar
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Grins, Jekabs
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Composition–property relationships of the La2O3–Al2O3–SiO2 glass system2010In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 356, no 20-22, p. 1043-1048Article in journal (Refereed)
    Abstract [en]

    We report physical properties of density, glass transition temperature, Vickers hardness and refractive index for 15 La–Al–Si–O glasses within the compositional region 10–28 mol% La2O3, 11–30% Al2O3 and 45–78% SiO2. The glass transition temperature varies only slightly between 871 and 883 °C. Both the density (3.25–4.33 g cm−3) and refractive index (1.59–1.70) display similar compositional dependencies and are primarily dictated by the La2O3 content. The hardness (6.4–9.0 GPa) increases with decreasing SiO2 content and to a minor extent also with the amount of La2O3 of the glass. The physical properties, in particular the hardness, are discussed with reference to glass structure. The similarity in the observed properties between the present oxide-based glasses and those of analogous rare-earth (RE) element-containing RE–Si–(Al)–O–N oxynitride glasses is highlighted and discussed in relation to the apparent, but hitherto largely neglected, role of RE-ions to primarily control many enhanced physical properties of oxynitride glasses.

  • 28.
    Iftekhar, Shahriar
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Grins, Jekabs
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Gunawidjaja, Philips N.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Glass Formation and Structure–Property–Composition Relations of theRE2O3–Al2O3–SiO2 (RE = La, Y, Lu, Sc) Systems2011In: Journal of The American Ceramic Society, ISSN 0002-7820, E-ISSN 1551-2916, Vol. 94, no 8, p. 2429-2435Article in journal (Refereed)
    Abstract [en]

    We report the glass-forming regions of the ternary Lu2O3–Al2O3–SiO2 and Sc2O3–Al2O3–SiO2 systems. The density, molarvolume, compactness, Vickers hardness, refractive index, aswell as the glass transition (Tg) and crystallization temperatureare compared for two series of RE–Al–Si–O (RE=La, Y, Lu,Sc) glasses that display a constant molar ratio nAl/nSi=1.00,whereas nRE/nSi is equal to either 0.62 or 0.94. Several glassproperties scale roughly linearly with the cation field strength(CFS) of the rare-earth (RE3+) ion, except for the Tg values ofthe Sc-bearing glasses that are significantly lower than expected.Magic-angle spinning 29Si and 27Al nuclear magneticresonance (NMR) reveal enhanced network disorder and increasedrelative populations of AlO5 and AlO6 polyhedra in thealuminosilicate glasses for increasing RE3+ CFS, but overallsimilar Si and Al local environments (chemical shifts and quadrupolarcouplings) in all samples associated with a constant nRE/nSi ratio, except for unexpectedly shielded 29Si NMR signalsobserved from the Sc–Al–Si–O glasses.

  • 29.
    Iftekhar, Shahriar
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Leonova, E.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Structural Characterizations of Lanthanum Aluminosilicate Glasses by 27Al and 29Si Solid State NMR2009In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 355, no 43-44, p. 2165-2174Article in journal (Refereed)
    Abstract [en]

    We investigate the network structures of LaSiAlO glasses by 29Si magic-angle-spinning (MAS) nuclear magnetic resonance (NMR). Their compositions span most of the glass-forming region of the ternary La2O3Al2O3SiO2 system at 1600 °C. The 29Si NMR resonances narrow and become progressively deshielded when Al substitutes for Si in the network, as well as for increasing La-content of the glass, which leads to network depolymerization. We compare experimental and calculated center of gravities of the 29Si NMR peaks, the latter generated from different simplified models for the distributions of Al and Si as well as bridging oxygen (BO) and non-bridging oxygen (NBO) atoms over the networks. The data do not permit accurate quantifications and may only be interpreted in limiting scenarios. However, they indicate that both distributions are essentially randomized, implying a clear deviation of the Al/Si ordering from that according to a Loewenstein Al-avoidance, coupled with a nearly uniform partitioning of the NBO atoms between Al and Si tetrahedra.

  • 30.
    Iftekhar, Shahriar
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Pahari, Bholanath
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Okhotnikov, Kirill
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Jaworski, Aleksander
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Stevensson, Baltzar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Grins, Jekabs
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Eden, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Properties and Structures of RE2O3-Al2O3-SiO2 (RE=Y, Lu) Glasses Probed by Molecular Dynamics Simulations and Solid-State NMR: The Roles of Aluminum and Rare-Earth Ions for Dictating the Microhardness2012In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 116, no 34, p. 18394-18406Article in journal (Refereed)
    Abstract [en]

    By combining molecular dynamics (MD) simulations with Si-29 and Al-27 magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy, we present a comprehensive structural report on rare-earth (RE) aluminosilicate (AS) glasses of the RE2O3-Al2O3-SiO2 (RE = Y, Lu) systems, where the latter is studied for the first time. The structural variations stemming from changes in the glass composition within each RE system as well as the effects of the increased cation field-strength (CFS) of Lu3+ relative to Y3+-are explored and correlated to measured physical properties, such as density, molar volume, glass transition temperature, and Vickers hardness (H-V). Si-29 NMR reveals a pronounced network ordering for an increase in either the RE or Al content of the glass. Al mainly assumes tetrahedral coordination, but significant AlO5 and AlO6 populations are present in all structures, with elevated amounts in the Lu-bearing glasses compared to their Y analogues. The MD-derived oxygen speciation comprises up to 3% of free O2- ions, as well as non-negligible amounts (4-19%) of O-[3] coordinations (oxygen triclusters). While the SiO4 groups mainly accommodate the nonbridging oxygen ions, a significant fraction thereof is located at the AlO4 tetrahedra, in contrast to the scenario of analogous alkali- and alkaline-earth metal-based AS glasses. The average coordination numbers (CNs) of Al and RE progressively increase for decreasing Si content of the glass, with the average CN of the RE3+ ions depending linearly on both the amount of Si and the fraction of AlO5 groups in the structure. The Vickers hardness correlates strongly with the average CN of Al, in turn dictated by the CFS and content of the RE3+ ions. This is to our knowledge the first structural rationalization of the well-known compositional dependence of H-V in RE bearing AS glasses.

  • 31.
    Jaworski, Aleksander
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Charpentier, Thibault
    Stevensson, Baltzar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Scandium and Yttrium Environments in Aluminosilicate Glasses Unveiled by Sc-45/Y-89 NMR Spectroscopy and DFT Calculations: What Structural Factors Dictate the Chemical Shifts?2017In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 34, p. 18815-18829Article in journal (Refereed)
    Abstract [en]

    Aluminosilicate (AS) glasses incorporating rare-earth (RE) elements exhibit favorable mechanical and (magneto)optical properties that reflect their unusual structural Organization. Yet, experimental reports on the local RE3+ environments in AS glasses are very sparse. We examine the Y3+ and Sc3+ cations in Y2O3-Al2O3-SiO2 and Sc2O3-Al2O3-SiO2 glasses of variable RE/Al/Si contents by utilizing magic-angle spinning (MAS) Y-89 and Sc-45 nuclear magnetic resonance (NMR) experiments coupled with density functional theory (DFT) calculations of Y-89/Sc-45 NMR chemical shifts. The DFT models reveal {Y-[p]} and {Sc-[p]} coordination numbers (p) spanning 5 <= p <= 8 and 4 <= p <= 7, respectively; with {Y-[6], Y-[7] and {Sc-[5], Sc-[6]} species dominating. Wide isotropic chemical shift ranges of 35-354 ppm (Y-89) and'48-208 ppm (Sc-45) are observed, as well as sizable shift'anisotropies up to approximate to 370 ppm and approximate to 250 ppm for Y-89 and Sc-45, respectively. Both the isotropic and anisotropic chemical shifts grow when the coordination number p is decreased for Y-89([p]) as well as Sc-45([p]). Second to the coordination number, we demonstrate that the Y-89/Sc-45 isotropic chemical shifts are mainly influenced by the RE/Al/Si constellation in the second coordination sphere of Y and Sc; where the shift tends to increase for emphasized contacts with neighboring RE and Al species at the expense of Si. These DFT-derived trends are corroborated by a progressive 89Y deshielding observed in MAS Y-89 NMR spectra for increasing Y and/or Al content of the glass. We also introduce heteronuclear MAS NMR experimentation involving the pairs of Y-89-Al-27 and Sc-45-Si-29 nuclides, utilized for probing the contacts between the Y3+/Sc3+ cations and the AS glass-network forming groups.

  • 32.
    Jaworski, Aleksander
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Stevensson, Baltzar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Direct O-17 NMR experimental evidence for Al-NBO bonds in Si-rich and highly polymerized aluminosilicate glasses2015In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 17, no 28, p. 18269-18272Article in journal (Refereed)
    Abstract [en]

    By using solid-state O-17 NMR spectroscopy, we provide the first direct experimental evidence for bonds between Al and non-bridging oxygen (NBO) ions in aluminosilicate glasses based on rare-earth (RE) elements, where RE = {Lu, Sc, Y}. The presence of similar to 10% Al-NBO moieties out of all NBO species holds regardless of the precise glass composition, at odds with the conventional structural view that Al-NBO bonds are absent in highly polymerized and Si-rich aluminosilicate glass networks.

  • 33.
    Jaworski, Aleksander
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Stevensson, Baltzar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Sc and Y Environments in Rare-Earth Aluminosilicate Glasses Unveiled by 45Sc and 89Y NMR Spectroscopy, MD Simulations, and DFT CalculationsManuscript (preprint) (Other academic)
  • 34.
    Jaworski, Aleksander
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Stevensson, Baltzar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    The Bearings from Rare-Earth (RE = La, Lu, Sc, Y) Cations on the Oxygen Environments in Aluminosilicate Glasses: A Study by Solid State O-17 NMR, Molecular Dynamics Simulations, and DFT Calculations2016In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, no 24, p. 13181-13198Article in journal (Refereed)
    Abstract [en]

    Aluminosilicate (AS) glasses incorporating trivalent cations of rare-earth (RE) elements exhibit a significant structural disorder and manifest building blocks incommensurate with conventional glass structure models. We present a comprehensive experimental and computational study of the O speciations in RE2O3-Al2O3-SiO2 glasses with RE = {La3+, Y3+, Lu3+, Sc3+}, where the cations are ordered according to increasing field-strength. The coexisting O-17([p])-Sip-mAlm moieties were quantified by magic-angle-spinning (MAS) O-17 nuclear magnetic resonance (NMR) experiments and atomistic molecular dynamics (MD) simulations. Experimental O-17 quadrupolar products ((C) over bar (Qn)) and isotropic chemical shifts ((delta) over bar (iso)) agreed well with predictions from density functional theory with the projector augmented wave (PAW) and gauge including PAW approaches, respectively. We highlight an observed strong influence of both {(delta) over bar (iso), (C) over bar (Qn)} NMR parameters on the average number of O-17([p])-RE3+ contacts ((q) over bar) and establish simple correlations between g and each of Sisc, and CQ, that encompass mA.1, moieties with 1 < p < 3. The quadrupolar product of each O-[p]-Sip-mAlm motif depends linearly on the all fractional ionicity of,the bonds to the 170 site, which is readily calculated from the parameter set {m, p, (q) over bar} with (q) over bar extracted from the MD-generated glass models. We rationalize and discuss the stability of each O[p]-Sip-mAlm moiety using bond valence sums evaluated on the MD-derived RE AS glass models: all comprise non-negligible populations of unconventional 0 species, such as free O2- ions (O-[0] coordinations), and oxygen triclusters (O-[3]-SiAl2 and O-[3]-Al-3). The triclusters preferentially connect high-coordination Al-[5]/Al-[6] species via edge-sharing, where the participation in corner or edge shared polyhedra is reflected in the {(delta) over bar (iso), (C) over bar (Qn)} O-17 NMR parameters.

  • 35.
    Jaworski, Aleksander
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Stevensson, Baltzar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    The Bearings from Rare-Earth (RE=La, Lu, Sc, Y) Cations on the Oxygen Environments in Aluminosilicate Glasses: A Study by Solid-State 17O NMR, Molecular Dynamics Simulations and DFT CalculationsManuscript (preprint) (Other academic)
  • 36.
    Jaworski, Aleksander
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Stevensson, Baltzar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Pahari, Bholanath
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Okhotnikov, Kirill
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Eden, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Local structures and al/si ordering in lanthanum aluminosilicate glasses explored by advanced al 27 nmr experiments and molecular dynamics simulations2012In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 14, no 45, p. 15866-15878Article in journal (Refereed)
    Abstract [en]

    The structures of 15 La-Al-Si-O glasses, whose compositions span 11-28 mol% La2O3, 11-30 mol% Al2O3, and 45-78 mol% SiO2, are explored over both short and intermediate length-scales by using a combination of solid-state Al-27 magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations. MAS NMR reveals Al speciations dominated by AlO4 groups, with minor but significant fractions of AlO5 (5-10%) and AlO6 (less than or similar to 3%) polyhedra present in all La2O3-Al2O3-SiO2 glasses; the amounts of Al-[5] and Al-[6] coordinations increase for decreasing molar fraction of Si. The MD simulations reproduce this compositional trend, with the fractional populations of AlOp groups (p = 4, 5, 6) according well with the experimental results. The modeled La speciations mainly involve LaO6 and LaO7 polyhedra, giving a range of average La3+ coordination numbers between 6.0 and 6.6; the latter increases slightly for decreasing Si content of the sample. Besides the expected bridging and non-bridging O species, minor contributions of oxygen triclusters (<= 9%) and free O-2(-) ions (<= 4%) are observed in all MD data. The glass structures exhibit a pronounced Al/Si disorder; the MD simulations reveal essentially random SiO4-SiO4, SiO4-AlOp and AlOp-AlOq (p, q = 4, 5, 6) associations, including significant amounts of AlO4-AlO4 contacts, regardless of the n(Al)/n(Si) molar ratio of the glass. The strong violation of Al-[4]-Al-[4] avoidance is verified by 2D Al-27 NMR experimentation that correlates double-quantum and single-quantum coherences, here applied for the first time to aluminosilicate glasses, and evidencing AlOp-AlOq connectivities dominated by AlO4-AlO4 and AlO4-AlO5 pairs. The potential bearings from distinct fictive temperatures of the experimental and modeled glass structures are discussed.

  • 37. Karlsson, Stefan
    et al.
    Mathew, Renny
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Ali, Sharafat
    Paemurru, Mart
    Anton, Johan
    Stevensson, Baltzar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Mechanical, thermal, and structural investigations of chemically strengthened Na2O–CaO–Al2O3–SiO2 glasses2022In: Frontiers in Materials, ISSN 2296-8016, Vol. 9, article id 953759Article in journal (Refereed)
    Abstract [en]

    For a series of conventional soda-lime-silicate glasses with increasing Al2O3 content, we investigated the thermal, mechanical, and structural properties before and after K+-for-Na+ ion-exchange strengthening by exposure to molten KNO3. The Al-for-Si replacement resulted in increased glass network polymerization and lowered compactness. The glass transition temperature (Tg), hardness (H) and reduced elastic modulus (Er), of the pristine glasses enhanced monotonically for increasing Al2O3 content. H and Er increased linearly up to a glass composition with roughly equal stoichiometric amounts of Na2O and Al2O3 where a nonlinear dependence on Al2O3 was observed, whereas H and Er of the chemically strengthened (CS) glasses revealed a strictly linear dependence. Tg, on the other hand, showed linear increase with Al-for-Si for pristine glasses while for the CS glasses a linear to nonlinear trend was observed. Solid-state 27Al nuclear magnetic resonance (NMR) revealed the sole presence of AlO4 groups in both the pristine and CS glasses. 23Na NMR and wet-chemical analysis manifested that all Al-bearing glasses had a lower and near-constant K+-for-Na+ ion exchange ratio than the soda-lime-silicate glass. Differential thermal analysis of CS glasses revealed a “blurred” glass transition temperature (Tg) and an exothermic step below Tg; the latter stems from the relaxation of residual compressive stresses. The nanoindentation-derived hardness at low loads and <5 mol% Al2O3 showed evidence of stress relaxation for prolonged ion exchange treatment. The crack resistance is maximized for molar ratios n(M(2)O)/n(Al2O3)≈1≈1 for the CS glasses, which is attributed to an increased elastic energy recovery that is linked to the glass compactness

  • 38.
    Konar, Sumit
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nylén, Johanna
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Svensson, Gunnar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bernin, Diana
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Ruschewitz, Uwe
    Häussermann, Ulrich
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    The many phases of CaC22016In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 239, p. 204-213Article in journal (Refereed)
    Abstract [en]

    Polymorphic CaC2 was prepared by reacting mixtures of CaH2 and graphite with molar ratios between 1:1.8 and 1:2.2 at temperatures between 700 and 1400 degrees C under dynamic vacuum. These conditions provided a well controlled, homogeneous, chemical environment and afforded products with high purity. The products, which were characterized by powder X-ray diffraction, solid state NMR and Raman spectroscopy, represented mixtures of the three known polymorphs, tetragonal CaC2-I and monoclinic CaC2-II and -III. Their proportion is dependent on the nominal C/CaH2 ratio of the reaction mixture and temperature. Reactions with excess carbon produced a mixture virtually free from CaC2-I, whereas high temperatures (above 1100 degrees C) and C-deficiency favored the formation of CaC2-I. From first principles calculations it is shown that CaC2-I is dynamically unstable within the harmonic approximation. This indicates that existing CaC2-I is structurally/dynamically disordered and may possibly even occur as slightly carbon-deficient phase CaC2-delta. It is proposed that monoclinic II is the ground state of CaC2 and polymorph III is stable at temperatures above 200 degrees C. Tetragonal I represents a metastable, heterogeneous, phase of CaC2. It is argued that a complete understanding of the occurrence of three room temperature modifications of CaC2 will require a detailed characterization of compositional and structural heterogeneities within the high temperature form CaC2-IV, which is stable above 450 degrees C. The effect of high pressure on the stability of the monoclinic forms of CaC2 was studied in a diamond anvil cell using Raman spectroscopy. CaC2-II and -III transform into tetragonal CaC2-I at about 4 and 1GPa, respectively.

  • 39.
    Leonova, Ekaterina
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Vallet Regi, Maria
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Lopez Noriega, Adolfo
    Arcos, Daniel
    Izquierdo Barba, Isabel
    Multinuclear Solid-State NMR Studies of Ordered Mesoporous Bioactive Glasses2008In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 112, no 14, p. 5552-5562Article in journal (Refereed)
    Abstract [en]

    The local structures of highly ordered mesoporous bioactive CaO-SiO2-P2O5 glasses were investigated for variable Ca contents. 1H NMR revealed a diversity of hydrogen-bonded and "isolated" surface silanols as well as adsorbed water molecules. The structural roles of Si and P were explored using a combination of 29Si and 31P magic-angle spinning (MAS) nuclear magnetic resonance (NMR) techniques; the proximities of Si and P to protons were studied through cross-polarization-based experiments, including 1H-29Si and 1H-31P hetero-nuclear two-dimensional correlation spectroscopy. The results are consistent with SiO2 being the main pore-wall component, whereas P is present as a separate amorphous calcium orthophosphate phase, which is dispersed over the pore wall as nanometer-sized clusters. The excess Ca that is not consumed in the phosphate phase modifies the silica glass network where it associates at/near the mesoporous surface. This biphasic structural model of the pore wall leads to the high accessibility of both Ca and P to body fluids, and its relation to the experimentally demonstrated high in vitro bioactivities of these materials is discussed.

  • 40.
    Leonova, Ekaterina
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Grins, Jekabs
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Shariatgorji, Mohammadreza
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Ilag, Leopold L.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Eden, Mattias
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Solid-state NMR investigations of Si-29 and N-15 enriched silicon nitride2009In: Solid State Nuclear Magnetic Resonance, ISSN 0926-2040, E-ISSN 1527-3326, Vol. 36, no 1, p. 11-18Article in journal (Refereed)
  • 41.
    Leonova, Ekaterina
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Hakeem, Abbas S.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Jansson, Kjell
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Stevensson, Baltzar
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Grins, Jekabs
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Esmaeilzadeh, Saeid
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Nitrogenrich La-Si-Al-O-N oxynitride glass structures probed by solid state NMR2008In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 354, no 1, p. 49-60Article in journal (Refereed)
    Abstract [en]

    We investigate the local structures of oxynitride La–Si–(Al)–O–N glasses by 29Si and 27Al magic-angle spinning (MAS) solid state Nuclear Magnetic Resonance (NMR). The glasses studied span an unprecedented range of compositions, up to >50 at.% lanthanum and nitrogen out of the cations and anions, respectively, and achievable through a recently introduced glass preparation route. Transmission as well as scanning electron microscopy verified homogeneous samples over length-scales down to 20 nm. As the nitrogen content of the glasses increased, 29Si NMR evidenced a progressive formation of Si–N bonds, with SiO2N2 tetrahedra dominating in the nitrogen-rich glass networks. In the oxygen-rich end of the series, aluminum is predominantly present in tetrahedral coordination as AlO4, whereas the glasses with highest nitrogen contents have a major fraction of AlO3N structural units. Trends in isotropic 29Si and 27Al chemical shifts and 27Al quadrupolar couplings are compared with results of La–Si–Al–O glasses and are discussed in relation to the glass compositions and their proposed structures.

  • 42.
    Li, Yunxiang
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zheng, Haoquan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Yun, Yifeng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bernin, Diana
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Gao, Feifei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    De-agglomeration of IZM-2 zeolite crystals by post-synthetic treatment2016In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 225, p. 185-191Article in journal (Refereed)
    Abstract [en]

    Highly intergrown nanocrystals are commonly observed in zeolite samples, and the densely packed agglomerates may result in small secondary porosity, which restricts the advantage of hierarchical structures. In this work we take IZM-2 zeolite as an example to demonstrate a post-treatment method with diluted hydrofluoric acid solution, which de-agglomerates intergrown zeolite nanocrystals and improves the secondary porosity. The treated samples preserve high crystallinity, similar framework composition and distinctively higher external surface area compared to the agglomerated ones. The results show that this treatment is an effective method for de-agglomeration of intergrown nanocrystals without affecting the original framework.

  • 43. Limbach, René
    et al.
    Karlsson, Stefan
    Scannell, Garth
    Mathew, Renny
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wondraczek, Lothar
    The effect of TiO2 on the structure of Na2O-CaO-SiO2 glasses and its implications for thermal and mechanical properties2017In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 471, p. 6-18Article in journal (Refereed)
    Abstract [en]

    Titania represents an important compound for property modifications in the widespread family of soda lime silicate glasses. In particular, such titania-containing glasses offer interesting optical and mechanical properties, for example, for substituting lead-bearing consumer glasses. Here, we provide a systematic study of the effect of TiO2 on the structural, thermal, and mechanical properties for three series of quaternary Na2O-CaO-TiO2-SiO2 glasses with TiO2 concentrations up to 12 mol% and variable Na2O, CaO, and SiO2 contents. Structural analyses by Raman and magic-angle spinning Si-29 NMR spectroscopy reveal the presence of predominantly four-fold coordinated Ti-[4] atoms in glasses of low and moderate TiO2 concentrations, where Si-O-Si bonds are replaced by Si-O-Ti-[4] bonds that form a network of interconnected TiO4 and SiO4 tetrahedra, with a majority of the non bridging oxygen ions likely being located at the SiO4 tetrahedra. At higher TiO2 contents, TiO5 polyhedra are also formed. Incorporation of TiO2 strongly affects the titanosilicate network connectivity, especially when its addition is accompanied by a decrease of the CaO content. However, except for the thermal expansion coefficient, these silicate-network modifications seem to have no impact on the thermal and mechanical stability. Instead, the compositional dependence of the thermal and mechanical properties on the TiO2 content stems from its effect on the network energy and packing efficiency.

  • 44.
    Lv, Peng
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry. Lanzhou University, PR China.
    Stevensson, Baltzar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Yu, Yang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Wang, Tieshan
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    BO3/BO4 Intermixing in Borosilicate Glass Networks Probed by Double-Quantum 11B NMR: What Factors Govern BO4-BO4 Formation?2023In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 127, no 40, p. 20026-20040Article in journal (Refereed)
    Abstract [en]

    We examine the borate group intermixing in a series of 25 borosilicate (BS) glasses from the [0.5M(2)O–0.5Na2O]–B2O3–SiO2 systems with M = {Li, K, Rb, Mg, Ca} along with ternary K2O–B2O3–SiO2 and Na2O–B2O3–SiO2 glasses by double-quantum–single-quantum (2Q–1Q) 11B correlation nuclear magnetic resonance (NMR) experiments. The alterations of the fractional populations of B[3]–O–B[3], B[3]–O–B[4], and B[4]–O–B[4] linkages in the glass networks were monitored for variable nSi/nB molar ratios, nonbridging O contents of the glass, and the (average) cation field strength (CFS) of the Mz+/Na+ network modifiers. A significant B[4]–O–B[4] bonding is observed in all glasses, thereby conclusively demonstrating that the normally assumed “BO4–BO4 avoidance” is far from strict in BS glasses, regardless of the Mz+ field strength. We show that the degree of B[4]–O–B[4] bonding depends foremost on its underlying BO4 population and to a lesser degree on the NBO content of the glass; we also provide a straightforward prediction of the B[4]–O–B[4] population in an arbitrary BS glass from parameters readily obtained by routine 11B NMR. The propensity for forming B[4]–O–B[4] linkages increases concurrently with either the CFS or the amount of glass network modifiers, roughly scaling as the square root of the “effective CFS” that encompasses both parameters. Although BO3–BO3 and BO3–BO4 pairs remain favored throughout all examined BS glass networks, the borate group intermixing randomizes significantly for increasing effective CFS, out of which the amount and charge of the glass-network modifier cations dominate over their size. Our results are discussed in relation to the two prevailing but formally mutually exclusive “random network” and “superstructural unit” models of borate and BS glasses.

  • 45.
    Lv, Zhong-Peng
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Lanzhou University, China.
    Sun, Zhao
    Wang, Fugang
    Yu, Yang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Yang, Fan
    Yue, Shengjun
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry. Lanzhou University, China.
    Chen, Liang
    Wang, Tieshan
    Cation field-strength effects on ion irradiation-induced mechanical property changes of borosilicate glass structures2023In: Journal of The American Ceramic Society, ISSN 0002-7820, E-ISSN 1551-2916, Vol. 106, no 10, p. 5766-5780Article in journal (Refereed)
    Abstract [en]

    We examine the impact of the glass network-modifier cation field strength (CFS) on ion irradiation-induced mechanical property changes in borosilicate (BS) glasses for the ternary M2O-B2O3-SiO2 systems with M = {Na, K, Rb} and the quaternary [0.5M((2))O-0.5Na(2)O]-B2O3-SiO2 systems with M = {Li, Na, K, Rb Mg, Ca, Sr, Ba}. B-11 nuclear magnetic resonance (NMR) experiments on the as-prepared BS glasses yielded the fractional population of four-coordinated B species (B-[4]) out of all {B-[3], B-[4]} groups in the glass network, along with the fraction of B-[4]-O-Si linkages out of all B-[4]-O-Si/B bonds. Both parameters correlated linearly with the (average) CFS of the M+ and/or {M(2)+, Na+} cations. Both the nanoindentation-derived hardness and Young's modulus values of the glasses reduced upon their irradiation by Si2+ ions, with the property deterioration decreasing linearly with increasing Mz+ CFS, that is, for higher Mz+center dot center dot center dot O interaction strength. The irradiation damage of the glass network also increased linearly with the fraction of B-[4]-O-Si linkages, which are the second weakest in the structure after the Mz+center dot center dot center dot O bonds. Our results underscore the advantages of employing BS glasses with high-CFS cations for enhancing the radiation resistance for nuclear waste storage.

  • 46.
    Lv, Zhong-Peng
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Lanzhou University, PR China.
    Wang, Chunting
    Stevensson, Baltzar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Yu, Yang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wang, Tieshan
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Impact of the cation field strength on physical properties and structures of alkali and alkaline-earth borosilicate glasses2022In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 48, no 13, p. 18094-18107Article in journal (Refereed)
    Abstract [en]

    The impact of the cation field strength (CFS) of the glass network-modifier cations on the structure and properties of borosilicate glasses (BS) were examined for a large ensemble of mixed-cation (R/2)M(2)O–(R/2)Na2O–B2O3–KSiO2 glasses with M+ ={Li+, Na+, K+, Rb+} and M2+ ={Mg2+, Ca2+, Sr2+, Ba2+} from four series of {K, R} combinations of K = n(SiO2)/n(B2O3) = {2.0, 4.0} and R =[n(M(2)O) ​+ ​n(Na2O)]/n(B2O3) = {0.75, 2.1}. Combined with results from La3+ bearing glasses enabled the probing of physical-property variations across a wide CFS range, encompassing the glass transition temperature (Tg), density, molar volume and compactness, as well as the hardness (H) and Young's modulus (E). We discuss the inferred composition–structure/CFS–property relationships. Each of Tg, H, and E revealed a non-linear dependence against the CFS and a strong Tg/H correlation, where each property is maximized for the largest alkaline-earth metal cations, i.e., Sr2+ and Ba2+, along with the high-CFS La3+ species. The 11B MAS NMR-derived fractional BO4 populations decreased linearly with the average Mz+/Na+ CFS within both K–0.75 glass branches, whereas the NBO-rich K–2.1 glasses manifested more complex trends. Comparisons with results from RM2O–B2O3–KSiO2 glasses suggested no significant “mixed alkali effect”.

  • 47.
    Majhi, Debashis
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Stevensson, Baltzar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nguyen, Tran Tra Mi
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    1H and 13C chemical shift-structure effects in anhydrous β-caffeine and four caffeine-diacid cocrystals probed by solid-state NMR experiments and DFT calculations2024In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084Article in journal (Refereed)
    Abstract [en]

    By using density functional theory (DFT) calculations, we refined the H atom positions in the structures of β-caffeine (C), α-oxalic acid (OA; (COOH)2), α-(COOH)2·2H2O, β-malonic acid (MA), β-glutaric acid (GA), and I-maleic acid (ME), along with their corresponding cocrystals of 2 : 1 (2C–OA, 2C–MA) or 1 : 1 (C–GA, C–ME) stoichiometry. The corresponding 13C/1H chemical shifts obtained by gauge including projector augmented wave (GIPAW) calculations agreed overall very well with results from magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy experiments. Chemical-shift/structure trends of the precursors and cocrystals were examined, where good linear correlations resulted for all COO1H sites against the H⋯O and/or H⋯N H-bond distance, whereas a general correlation was neither found for the aliphatic/caffeine-stemming 1H sites nor any 13C chemical shift against either the intermolecular hydrogen- or tetrel-bond distance, except for the 13COOH sites of the 2C–OA, 2C–MA, and C–GA cocrystals, which are involved in a strong COOHN bond with caffeine that is responsible for the main supramolecular stabilization of the cocrystal. We provide the first complete 13C NMR spectral assignment of the structurally disordered anhydrous β-caffeine polymorph. The results are discussed in relation to previous literature on the disordered α-caffeine polymorph and the ordered hydrated counterpart, along with recommendations for NMR experimentation that will secure sufficient 13C signal-resolution for reliable resonance/site assignments.

  • 48.
    Mathew, Renny
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Gunawidjaja, Philips N.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Izquierdo-Barba, Isabel
    Jansson, Kjell
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Garcia, Ana
    Arcos, Daniel
    Vallet-Regi, Maria
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Solid-State (31)P and (1)H NMR Investigations of Amorphous and Crystalline Calcium Phosphates Grown Biomimetically From a Mesoporous Bioactive Glass2011In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 115, no 42, p. 20572-20582Article in journal (Refereed)
    Abstract [en]

    By exploiting (1)H and (31)P magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy, we explore the proton and orthophosphate environments in biomimetic amorphous calcium phosphate (ACP) and hydroxyapatite (HA), as grown in vitro at the surface of a 10CaO-85SiO(2)-5P(2)O(5) mesoporous bioactive glass (MBG) in either a simulated body fluid or buffered water. Transmission electron microscopy confirmed the presence of a calcium phosphate layer comprising nanocrystalline HA Two-dimensional (1)H-(31)P heteronudear correlation NMR established predominantly (1)H(2)O <->(31)PO(4)(3-) and O(1)H <->(31)PO(4)(3-) contacts in the amorphous and crystalline component, respectively, of the MBG surface-layer; these two pairs exhibit distinctly different (1)H <->(31)P cross-polarization dynamics, revealing a twice as large squared effective (1)H-(31)P dipolar coupling constant in ACP compared with HA. These respective observations are mirrored in synthetic (well-crystalline) HA, and the amorphous calcium orthophosphate (CaP) clusters that are present in the pristine MBG pore walls: besides highlighting very similar local (1)H and (31)P environments in synthetic and biomimetic HA, our findings evidence closely related NMR characteristics, and thereby similar local structures, of the CaP clusters in the pristine MBG relative to biomimetic ACP.

  • 49.
    Mathew, Renny
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Pujari-Palmer, Michael
    Guo, Hua
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Yu, Yang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Stevensson, Baltzar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Engqvist, Håkan
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Solid-State NMR Rationalizes the Bone-Adhesive Properties of Serine- and Phosphoserine-Bearing Calcium Phosphate Cements by Unveiling Their Organic/Inorganic Interface2020In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 124, no 39, p. 21512-21531Article in journal (Refereed)
    Abstract [en]

    From a multitude of homonuclear and heteronuclear correlation magic-angle-spinning (MAS) NMR experiments, we present thorough structural and phase-quantification analyses of calcium phosphate cements (CPCs) that incorporate either L-serine (Ser) or O-phospho-L-serine (Pser), thereby rendering the cements strongly bone-adhesive and suitable for biomedical implants with capacity to glue both soft and hard tissues together. In the absence of organic additives, the CPCs comprise disordered hydroxyapatite (HA), which forms from the reaction of alpha-Ca-3(PO4)(2) with water. However, the presence of even a few mol % of Pser/Ser drastically changes the cement reactions: the HA formation is quenched, while MAS NMR experiments reveal intimate contacts between the Pser/Ser molecules and amorphous calcium phosphate (ACP) that incorporate HPO42- groups: these organic/inorganic species form a homogeneous amorphous ACP/Pser or ACP/Ser cement component. The amount of ACP/Pser in the cement is shown to correlate qualitatively with its shear strength, also rationalizing why Pser-bearing CPCs exhibit stronger adhesive properties than their Ser-based counterparts, for which the ACP/Ser content does not increase concomitantly with that of Ser (as for the Pser-based CPCs). The Pser-bearing CPCs feature the strongest shear strength for 23-72 mol % Pser, whereas the decline of the adhesive properties for the Pser-richest CPCs (>72 mol %) stems from unreacted Pser and formation of its Ca salt, as well as several minor Ca phosphate phases involving HPO42- and H2PO4- groups. By combining information from various one- and two-dimensional MAS NMR experiments with H-1, C-13, and P-31 as structural probes, we examined the inorganic/organic contacts of the ACP/Pser and ACP/Ser phases, and monitored the alterations of the cement reactions for variable amounts of the organic additives.

  • 50.
    Mathew, Renny
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Stevensson, Baltzar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Na/Ca Intermixing around Silicate and Phosphate Groups in Bioactive Phosphosilicate Glasses Revealed by Heteronuclear Solid-State NMR and Molecular Dynamics Simulations2015In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 119, no 17, p. 5701-5715Article in journal (Refereed)
    Abstract [en]

    We characterize the intermixing of network-modifying Na+/Ca2+ ions around the silicate (QSin) and phosphate (QPn) tetrahedra in a series of 16 Na2O–CaO–SiO2–P2O5 glasses, whose P content and silicate network connectivity were varied independently. The set includes both bioactive and bioinactive compositions and also encompasses two soda-lime-silicate members devoid of P, as well as two CaO–SiO2 glasses and one Na2O–SiO2–P2O5 glass. The various Si/P↔Na/Ca contacts were probed by molecular dynamics (MD) simulations together with heteronuclear magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) experimentation utilizing 23Na{31P} and 23Na{29Si} REDOR, as well as 31P{ 23Na} and 29Si{23Na} REAPDOR. We introduce an approach for quantifying the extent of Na+/Ca2+ ordering around a given QPn or QSin group, encoded by the preference factor 0⩽ PM ⩽ 1 conveying the relative weights of a random cation intermixing (PM = 0) and complete preference/ordering (PM = 1) for one of the species M, which represents either Na+ or Ca2+. The MD-derived preference factors reveal phosphate and silicate species surrounded by Na+/Ca2+ ions intermixed nearly randomly (PM ≲ 0.15), except for the QSi4 and QSi1 groups, which manifest more significant cation ordering with preference for Na+ and Ca2+, respectively. The overall weak preferences are essentially independent of the Si and P contents of the glass, whereas PM primarily correlates with the total amount of network modifiers: as the latter is increased, the Na/Ca distribution around the {QP0, QSi1, QSi2} groups with preference for Ca2+ tend to randomize (i.e., PCa decreases), while the PNa-values grow slightly for the {QP1, QSi3, QSi4} species already preferring coordination of Na. The set of experimental preference factors {PCa} for the orthophosphate (QP0) groups extracted from 31P{23Na} REAPDOR NMR-derived M2(P–Na) dipolar second moments agrees well with the MD-generated counterparts. Our results on the Na/Ca intermixing in soda-lime-silicate glasses are discussed in relation to previous reports, highlighting the dependence of the conclusion on the approach to data evaluation.

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