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  • 1. Brunatova, Tereza
    et al.
    Popelkova, Daniela
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Oleynikov, Peter
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Danis, Stanislav
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Kuzel, Radomir
    Study of titanate nanotubes by X-ray and electron diffraction and electron microscopy2014In: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 87, p. 166-171Article in journal (Refereed)
    Abstract [en]

    The structure of titanate nanotubes (Ti-NTs) was studied by a combination of powder X-ray diffraction (PXRD), electron diffraction and high resolution transmission electron microscopy (HRTEM). Ti-NTs are prepared by hydrothermal treatment of TiO2 powder. The structure is identified by powder X-ray diffraction as the one based on the structure of H2Ti2O5 center dot H2O phase. The same structure is obtained by projected potential from HRTEM through-focus image series. The structure is verified by simulated PXRD pattern with the aid of the Debye formula. The validity of the model is tested by computing Fourier transformation of a single nanotube which is proportional to measured electron diffraction intensities. A good agreement of this calculation with measured precession electron diffraction data is achieved.

  • 2.
    Carson, Fabian
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Su, Jie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Platero-Prats, Ana E.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    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).
    Samain, Louise
    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).
    Framework Isomerism in Vanadium Metal-Organic Frameworks: MIL-88B(V) and MIL-101(V)2013In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 13, no 11, p. 5036-5044Article in journal (Refereed)
    Abstract [en]

    Two families of metal organic frameworks (MOFs), MIL-88 and MIL-101 built by trinuclear transition metal (TM) clusters (TM = Cr, Fe, or Sc), have been known for several years, but their syntheses are often reported separately. In fact, these MOFs are polymorphs, or framework isomers: they are assembled from the same metal secondary building units and organic linkers, but the connectivity of these components differs. Here we report for the first time the synthesis of the vanadium MOF MIL-88B(V) and compare its synthesis parameters to those of MIL-47(V) and the recently reported MIL-101(V). The properties of MIL-88B(V) and MIL-101(V) are remarkably different. MIL-88B(V) can breathe and is responsive to different solvents, while MIL-101(V) is rigid and contains mesoporous cages. MIL-101(V) exhibits the highest specific surface area among vanadium MOFs discovered so far. In addition, both MIL-88B(V) and MIL-101(V) transform to MIL-47 at higher temperatures. We have also identified the key synthesis parameters that control the formation of MIL-88B(V), MIL-101(V), and MIL-47: temperature, time, and pH. This relates to the rate of reaction between the metal and linkers, which has been monitored by ex situ X-ray powder diffraction and V K-edge X-ray absorption spectroscopy during MOF synthesis. It is therefore important to fully study the synthesis conditions to improve our understanding of framework isomerism in MOFs.

  • 3. Clabbers, M. T. B.
    et al.
    van Genderen, E.
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wiegers, E. L.
    Gruene, T.
    Abrahams, J. P.
    Protein structure determination by electron diffraction using a single three-dimensional nanocrystal2017In: Acta Crystallographica Section D Structural Biology, ISSN 2059-7983, Vol. 73, p. 738-748Article in journal (Refereed)
    Abstract [en]

    Three-dimensional nanometre-sized crystals of macromolecules currently resist structure elucidation by single-crystal X-ray crystallography. Here, a single nanocrystal with a diffracting volume of only 0.14 mu m(3), i.e. no more than 6 x 10(5) unit cells, provided sufficient information to determine the structure of a rare dimeric polymorph of hen egg-white lysozyme by electron crystallography. This is at least an order of magnitude smaller than was previously possible. The molecular-replacement solution, based on a monomeric polyalanine model, provided sufficient phasing power to show side-chain density, and automated model building was used to reconstruct the side chains. Diffraction data were acquired using the rotation method with parallel beam diffraction on a Titan Krios transmission electron microscope equipped with a novel in-house-designed 1024 x 1024 pixel Timepix hybrid pixel detector for low-dose diffraction data collection. Favourable detector characteristics include the ability to accurately discriminate single high-energy electrons from X-rays and count them, fast readout to finely sample reciprocal space and a high dynamic range. This work, together with other recent milestones, suggests that electron crystallography can provide an attractive alternative in determining biological structures.

  • 4. Cliffe, Matthew J.
    et al.
    Wan, Wei
    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).
    Chater, Philip A.
    Kleppe, Annette K.
    Tucker, Matthew G.
    Wilhelm, Heribert
    Funnell, Nicholas P.
    Coudert, Francois-Xavier
    Goodwin, Andrew L.
    Correlated defect nanoregions in a metal-organic framework2014In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 5, p. 4176-Article in journal (Refereed)
    Abstract [en]

    Throughout much of condensed matter science, correlated disorder is a key to material function. While structural and compositional defects are known to exist within a variety of metal-organic frameworks (MOFs), the prevailing understanding is that these defects are only ever included in a random manner. Here we show-using a combination of diffuse scattering, electron microscopy, anomalous X-ray scattering and pair distribution function measurements-that correlations between defects can in fact be introduced and controlled within a hafnium terephthalate MOF. The nanoscale defect structures that emerge are an analogue of correlated Schottky vacancies in rocksalt-structured transition metal monoxides and have implications for storage, transport, optical and mechanical responses. Our results suggest how the diffraction behaviour of some MOFs might be reinterpreted, and establish a strategy of exploiting correlated nanoscale disorder as a targetable and desirable motif in MOF design.

  • 5.
    Fang, Liang
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Liu, Leifeng
    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).
    Inge, A. Ken
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    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).
    Geo, Feifei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    SU-77: An Open-Framework Germanate Containing 12 × 10 × 10-Ring Channels Solved by Combining Rotation Electron Diffraction and Powder X-ray Diffraction2014In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 14, no 10, p. 5072-5078Article in journal (Refereed)
    Abstract [en]

    A novel open-framework germanate, denoted as SU-77, was prepared by hydrothermal synthesis using ethylenediamine as the structure directing agent. The as-synthesized SU-77 is monoclinic with space group P21/a and a = 13.52427(5) Å, b = 12.64862(5) Å, c = 9.60578(3) Å, β = 92.8599(4)°. The structure of SU-77 is built from a novel Ge6O17(C2H8N2)F (Ge6) cluster building unit. The Ge6 clusters are connected to form chains along the c-axis. These chains are further connected in the [110] and [1–10] directions to form a three-dimensional framework with 12 × 10 × 10-ring channels. The as-synthesized monoclinic SU-77 became orthorhombic while being observed in a transmission electron microscope (TEM) or when heated to 200 °C in air. The orthorhombic structure of SU-77 was solved from micrometer-sized crystals by rotation electron diffraction (RED). The monoclinic structure was built from the orthorhombic structure and subsequently refined against synchrotron powder X-ray diffraction data. SU-77 is the first example of an open-framework germanate with mixed coordination polyhedra solved by electron diffraction.

  • 6. Feng, Dawei
    et al.
    Liu, Tian-Fu
    Su, Jie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bosch, Mathieu
    Wei, Zhangwen
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Yuan, Daqiang
    Chen, Ying-Pin
    Wang, Xuan
    Wang, Kecheng
    Lian, Xizhen
    Gu, Zhi-Yuan
    Park, Jihye
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zhou, Hong-Cai
    Stable metal-organic frameworks containing single-molecule traps for enzyme encapsulation2015In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 6, p. 5979-Article in journal (Refereed)
    Abstract [en]

    Enzymatic catalytic processes possess great potential in chemical manufacturing, including pharmaceuticals, fuel production and food processing. However, the engineering of enzymes is severely hampered due to their low operational stability and difficulty of reuse. Here, we develop a series of stable metal-organic frameworks with rationally designed ultra-large mesoporous cages as single-molecule traps (SMTs) for enzyme encapsulation. With a high concentration of mesoporous cages as SMTs, PCN-333(Al) encapsulates three enzymes with record-high loadings and recyclability. Immobilized enzymes that most likely undergo single-enzyme encapsulation (SEE) show smaller Km than free enzymes while maintaining comparable catalytic efficiency. Under harsh conditions, the enzyme in SEE exhibits better performance than free enzyme, showing the effectiveness of SEE in preventing enzyme aggregation or denaturation. With extraordinarily large pore size and excellent chemical stability, PCN-333 may be of interest not only for enzyme encapsulation, but also for entrapment of other nanoscaled functional moieties.

  • 7. Garcia-Martinez, Javier
    et al.
    Xiao, Changhong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Cychosz, Katie A.
    Li, Kunhao
    Wan, Wei
    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).
    Thommes, Matthias
    Evidence of Intracrystalline Mesostructured Porosity in Zeolites by Advanced Gas Sorption, Electron Tomography and Rotation Electron Diffraction2014In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 6, no 11, p. 3110-3115Article in journal (Refereed)
    Abstract [en]

    The small size of micropores (typically <1 nm) in zeolites causes slow diffusion of reactant and product molecules in and out of the pores and negatively impacts the product selectivity of zeolite based catalysts, for example, fluid catalytic cracking (FCC) catalysts. Size-tailored mesoporosity was introduced into commercial zeolite Y crystals by a simple surfactant-templating post-synthetic mesostructuring process. The resulting mesoporous zeolite Y showed significantly improved product selectivity in both laboratory testing and refinery trials. Advanced characterization techniques such as electron tomography, three-dimensional rotation electron diffraction, and high resolution gas adsorption coupled with hysteresis scanning and density functional theory, unambiguously revealed the intracystalline nature and connectivity of the introduced mesopores. They can be considered as molecular highways that help reactant and product molecules diffuse quickly to and away from the catalytically active sites within the zeolite crystals and, thus, shift the selectivity to favor the production of more of the valuable liquid fuels at reduced yields of coke and unconverted feed.

  • 8. Grushko, B.
    et al.
    Kapush, D.
    Su, Jie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Hovmöller, Sven
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Al-rich region of Al-Pt2013In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 580, p. 618-625Article in journal (Refereed)
    Abstract [en]

    The constitution of the Al-rich part of the Al-Pt alloy system is revised. Apart from the previously reported equilibrium Al4Pt, Al21Pt8 and Al2Pt phases, a complex intermetallic was revealed at 7576 at.% Al between 801 and 915 degrees C. Its structure determined by electron diffraction is orthorhombic (Bmmb, a = 1.983, b = 1.636 and c = 1.422 nm).

  • 9.
    Guo, Peng
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Chinese Academy of Sciences, China.
    Afeworki, Mobae
    Cao, Guang
    Yun, Yifeng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Su, Jie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    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).
    Synthesis and Structure of a Layered Fluoroaluminophosphate and Its Transformation to a Three-Dimensional Zeotype Framework2018In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 57, no 18, p. 11753-11760Article in journal (Refereed)
    Abstract [en]

    Two-dimensional zeolitic materials have drawn increasing attention because of their structural diversity, high accessible surface areas, and potential as precursors to form novel three-dimensional (3D) structures. Here we report a new layered fluoroaluminophosphate, denoted as EMM-9 (ExxonMobil Material #9), synthesized in the same synthesis system as that for a previously reported 3D framework structure EMM-8 (framework-type code: SFO) using an F- medium and 4-(dimethylamino)pyridine (DMAP) as the organic structure-directing agent. The structure of EMM-9 was solved from rotation electron diffraction data and refined against synchrotron powder X-ray diffraction data. The fluoroaluminophosphate layer of EMM-9 is composed of sti composite building units. The DMAP cations are located between the layers. pi-pi interactions between the DMAP cations and hydrogen bonding between the DMAP cations and layers were identified. The layered EMM-9 structure is closely related to the 3D framework structure of EMM-8 and can be transformed to EMM-8 by calcination.

  • 10.
    Guo, Peng
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Cao, Guang
    Afeworki, Mobae
    Yun, Yifeng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Su, Jie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    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).
    Synthesis and Structure Determination of a Layered Zeolitic Fluoroaluminophosphate and its Transformation to a Three-dimensional Zeolite FrameworkManuscript (preprint) (Other academic)
  • 11.
    Guo, Peng
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Liu, Leifeng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Yun, Yifeng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Su, Jie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Gies, Hermann
    Zhang, Haiyan
    Xiao, Feng-Shou
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Ab initio structure determination of interlayer expanded zeolites by single crystal rotation electron diffraction2014In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 43, no 27, p. 10593-10601Article in journal (Refereed)
    Abstract [en]

    Layered solids often form thin plate-like crystals that are too small to be studied by single-crystal X-ray diffraction. Although powder X-ray diffraction (PXRD) is the conventional method for studying such solids, it has limitations because of peak broadening and peak overlapping. We have recently developed a software-based rotation electron diffraction (RED) method for automated collection and processing of 3D electron diffraction data. Here we demonstrate the ab initio structure determination of two interlayer expanded zeolites, the microporous silicates COE-3 and COE-4 (COE-n stands for International Network of Centers of Excellence-n), from submicron-sized crystals by the RED method. COE-3 and COE-4 are built of ferrierite-type layers pillared by (-O-Si(CH3)(2)-O-) and (-O-Si(OH)(2)-O-) linker groups, respectively. The structures contain 2D intersecting 10-ring channels running parallel to the ferrierite layers. Because both COE-3 and COE-4 are electron-beam sensitive, a combination of RED datasets from 2 to 3 different crystals was needed for the structure solution and subsequent structure refinement. The structures were further refined by Rietveld refinement against the PXRD data. The structure models obtained from RED and PXRD were compared.

  • 12.
    Guo, Peng
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    McCusker, Lynne
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Laboratory of Crystallography, ETH Zurich, Switzerland.
    Baerlocher, Christian
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    On the relationship between unit cells and channel systems in high silica zeolites with the butterfly projection2015In: Zeitschrift für Kristallographie - Crystalline Materials, ISSN 2194-4946, Vol. 230, no 5, p. 301-309Article in journal (Refereed)
    Abstract [en]

    Zeolites are crystalline aluminosilicate framework materials with corner sharing TO 4 (T = Al, Si) tetrahedra forming well-defined pores and channels. Many zeolites are built from similar building units (i.e., isolated units, chains or layers), which are connected in different ways to form a variety of topologies. We have identified ten zeolite frameworks that share the same two-dimensional butterfly net containing 5-, 6- and 10-rings: (MRE)-M-star, FER, MEL, SZR, MFS, MFI, TUN, IMF, BOG and TON. Different orientations of the TO4 tetrahedra within the layer lead to different connectivities between neighboring layers. Some layers are corrugated and some are flat, resulting in different channel systems parallel to the layer. We found some interesting relationships between the unit cell parameters and this channel system that allow the size of the channels and their directions to be deduced from the unit cell dimensions. This may facilitate the prediction of new members of this zeolite family. In addition, other zeolites containing the butterfly layers are also discussed.

  • 13.
    Li, Duan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Guo, Peng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Guzi de Moraes, Elisângela
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zou, Ji
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Colombo, Paolo
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Structural study of disordered SiC nanowires by three-dimensional rotation electron diffraction2014In: Materials Research Express, ISSN 2053-1591, Vol. 1, no 4, article id 045023Article in journal (Refereed)
    Abstract [en]

    The structure of disordered SiC nanowires was studied by using the three-dimensional rotation electron diffraction (RED) technique. The streaks shown in the RED images indicated the stacking faults of the nanowire. High-resolution transmission electron microscopy imaging was employed to support the results from the RED data. It suggested that a 2H polytype is most possible for the nanowires.

  • 14. Martinez-Franco, Raquel
    et al.
    Moliner, Manuel
    Yun, Yifeng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Peking University, China.
    Wan, Wei
    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).
    Corma, Avelino
    Synthesis of an extra-large molecular sieve using proton sponges as organic structure-directing agents2013In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 110, no 10, p. 3749-3754Article in journal (Refereed)
    Abstract [en]

    The synthesis of crystalline microporous materials containing large pores is in high demand by industry, especially for the use of these materials as catalysts in chemical processes involving bulky molecules. An extra-large-pore silicoaluminophosphate with 16-ring openings, ITQ-51, has been synthesized by the use of bulky aromatic proton sponges as organic structure-directing agents. Proton sponges show exceptional properties for directing extra-large zeolites because of their unusually high basicity combined with their large size and rigidity. This extra-large-pore material is stable after calcination, being one of the very few examples of hydrothermally stable molecular sieves containing extra-large pores. The structure of ITQ-51 was solved from submicrometer-sized crystals using the rotation electron diffraction method. Finally, several hypothetical zeolites related to ITQ-51 have been proposed.

  • 15. Moliner, Manuel
    et al.
    Willhammar, Tom
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Gonzalez, Jorge
    Rey, Fernando
    Jorda, Jose L.
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Corma, Avelino
    Synthesis Design and Structure of a Multipore Zeolite with Interconnected 12-and 10-MR Channels2012In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, no 14, p. 6473-6478Article in journal (Refereed)
    Abstract [en]

    A new molecular sieve, ITQ-38, containing interconnected large and medium pores in its structure has been synthesized. The rational combination of dicationic piperidine-derivative molecules as organic structure directing agents (OSDAs) with germanium and boron atoms in alkaline media has allowed the synthesis of ITQ-38 zeolite. High-resolution transmission electron microscopy (HRTEM) has been used to elucidate the framework topology of ITQ-38, revealing the presence of domains of perfect ITQ-38 crystals as well as very small areas containing nanosized ITQ-38/ITQ-22 intergrowths. The structure of ITQ-38 is highly related to ITQ-22 and the recently described polymorph C of ITQ-39 zeolite. It shares a common building layer with ITQ-22 and contains the same building unit as the polymorph C of ITQ-39. All three structures present similar framework density, 16.1 T atoms/1000 angstrom(3).

  • 16.
    Pascanu, Vlad
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Yao, Qingxia
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bermejo Gomez, Antonio
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Gustafsson, Mikaela
    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).
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Samain, Louise
    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).
    Martin-Matute, Belen
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sustainable Catalysis: Rational Pd Loading on MIL-101Cr-NH2 for More Efficient and Recyclable Suzuki-Miyaura Reactions2013In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 19, no 51, p. 17483-17493Article in journal (Refereed)
    Abstract [en]

    Palladium nanoparticles have been immobilized into an amino-functionalized metal-organic framework (MOF), MIL-101Cr-NH2, to form Pd@MIL-101Cr-NH2. Four materials with different loadings of palladium have been prepared (denoted as 4-, 8-, 12-, and 16wt%Pd@MIL-101Cr-NH2). The effects of catalyst loading and the size and distribution of the Pd nanoparticles on the catalytic performance have been studied. The catalysts were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD), N-2-sorption isotherms, elemental analysis, and thermogravimetric analysis (TGA). To better characterize the palladium nanoparticles and their distribution in MIL-101Cr-NH2, electron tomography was employed to reconstruct the 3D volume of 8wt%Pd@MIL-101Cr-NH2 particles. The pair distribution functions (PDFs) of the samples were extracted from total scattering experiments using high-energy X-rays (60keV). The catalytic activity of the four MOF materials with different loadings of palladium nanoparticles was studied in the Suzuki-Miyaura cross-coupling reaction. The best catalytic performance was obtained with the MOF that contained 8wt% palladium nanoparticles. The metallic palladium nanoparticles were homogeneously distributed, with an average size of 2.6nm. Excellent yields were obtained for a wide scope of substrates under remarkably mild conditions (water, aerobic conditions, room temperature, catalyst loading as low as 0.15mol%). The material can be recycled at least 10times without alteration of its catalytic properties.

  • 17.
    Sahoo, Suman
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Lundberg, Helena
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Ahlsten, Nanna
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Martín-Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Single Site Supported Cationic Rhodium(I) Complexes for the Selective Redox Isomerization of Allylic Alcohols2012In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 4, no 2, p. 243-250Article in journal (Refereed)
    Abstract [en]

    The isomerization of allylic alcohols to carbonyl compounds by a heterogeneous rhodium complex is reported. Different silica material supports and catalyst/ligand systems were evaluated. The most efficient catalyst in terms of catalytic activity and stability was found to be a cationic rhodium(I) complex with sulfonated phosphine ligands anchored on a mesoporous aluminosilica AlSBA-15. The heterogeneous complex catalyzed the isomerization of a variety of allylic alcohols in excellent yields with very low catalyst loadings (0.5 mol %). The catalyst could be recycled without significant loss of activity or selectivity. The optimized catalyst was characterized by N2 sorption, powder X-ray diffraction, transmission electron microscopy, as well as solution and solid-state nuclear magnetic resonance, and Fourier Transform infrared spectroscopies.

  • 18.
    Singh, Devinder
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Panjab University, India.
    Yun, Yifeng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Grushko, Benjamin
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hovmoller, Sven
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Structure determination of a pseudo-decagonal quasicrystal approximant by the strong-reflections approach and rotation electron diffraction2016In: Journal of applied crystallography, ISSN 0021-8898, E-ISSN 1600-5767, Vol. 49, p. 433-441Article in journal (Refereed)
    Abstract [en]

    The structure of a complicated pseudo-decagonal (PD) quasicrystal approximant in the Al-Co-Ni alloy system, denoted as PD1, was solved by the strong-reflections approach on three-dimensional rotation electron diffraction (RED) data, using the phases from the known PD2 structure. RED shows that the PD1 crystal is primitive and orthorhombic, with a = 37.3, b = 38.8, c = 8.2 angstrom. However, as with other approximants in the PD series, the superstructure reflections (corresponding to c = 8.2 angstrom) are much weaker than those of the main reflections (corresponding to c = 4.1 angstrom), so it was decided to solve the PD1 structure in the smaller primitive unit cell first, i.e. with unit-cell parameters a = 37.3, b = 38.8, c = 4.1 angstrom and space group Pnam. A density map of PD1 was calculated from only the 15 strongest unique reflections. It contained all 31 Co/Ni atoms and many weaker peaks corresponding to Al atoms. The structure obtained from the strong-reflections approach was confirmed by applying direct methods to the complete RED data set. Successive refinement using the RED data set resulted in 108 unique atoms (31 Co/Ni and 77 Al). This is one of the most complicated approximant structures ever solved by electron diffraction. As with other approximants in the PD series, PD1 is built of characteristic 2 nm wheel clusters with fivefold rotational symmetry, which agrees with results from high-resolution electron microscopy images. The simulated electron diffraction patterns for the structure model are in good agreement with the experimental electron diffraction patterns obtained by RED.

  • 19.
    Singh, Devinder
    et al.
    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).
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Grushko, Benjamin
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hovmöller, Sven
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    A complex pseudo-decagonal quasicrystal approximant, Al-37(Co,Ni)(15.5), solved by rotation electron diffraction2014In: Journal of applied crystallography, ISSN 0021-8898, E-ISSN 1600-5767, Vol. 47, no 1, p. 215-221Article in journal (Refereed)
    Abstract [en]

    Electron diffraction is a complementary technique to single-crystal X-ray diffraction and powder X-ray diffraction for structure solution of unknown crystals. Crystals too small to be studied by single-crystal X-ray diffraction or too complex to be solved by powder X-ray diffraction can be studied by electron diffraction. The main drawbacks of electron diffraction have been the difficulties in collecting complete three-dimensional electron diffraction data by conventional electron diffraction methods and the very time-consuming data collection. In addition, the intensities of electron diffraction suffer from dynamical scattering. Recently, a new electron diffraction method, rotation electron diffraction (RED), was developed, which can overcome the drawbacks and reduce dynamical effects. A complete three-dimensional electron diffraction data set can be collected from a sub-micrometre-sized single crystal in less than 2 h. Here the RED method is applied for ab initio structure determination of an unknown complex intermetallic phase, the pseudo-decagonal (PD) quasicrystal approximant Al-37.0(Co,Ni)(15.5), denoted as PD2. RED shows that the crystal is F-centered, with a = 46.4, b = 64.6, c = 8.2 angstrom. However, as with other approximants in the PD series, the reflections with odd l indices are much weaker than those with l even, so it was decided to first solve the PD2 structure in the smaller, primitive unit cell. The basic structure of PD2 with unit-cell parameters a = 23.2, b = 32.3, c = 4.1 angstrom and space group Pnmm has been solved in the present study. The structure with c = 8.2 angstrom will be taken up in the near future. The basic structure contains 55 unique atoms (17 Co/Ni and 38 Al) and is one of the most complex structures solved by electron diffraction. PD2 is built of characteristic 2 nm wheel clusters with fivefold rotational symmetry, which agrees with results from high-resolution electron microscopy images. Simulated electron diffraction patterns for the structure model are in good agreement with the experimental electron diffraction patterns obtained by RED.

  • 20.
    Smeets, Stef
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Laboratory of Crystallography, Switzerland.
    Berkson, Zachariah J.
    Xie, Dan
    Zones, Stacey I.
    Wan, Wei
    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).
    Hsieh, Ming-Feng
    Chmelka, Bradley F.
    McCusker, Lynne B.
    Baerlocher, Christian
    Well-Defined Silanols in the Structure of the Calcined High-Silica Zeolite SSZ-70: New Understanding of a Successful Catalytic Material2017In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 139, no 46, p. 16803-16812Article in journal (Refereed)
    Abstract [en]

    The structure of the calcined form of the high-silica zeolite SSZ-70 has been elucidated by combining synchrotron X-ray powder diffraction (XRPD), high-resolution transmission electron microscopy (HRTEM), and two-dimensional (2D) dynamic nuclear polarization (DNP)-enhanced NMR techniques. The framework structure of SSZ-70 is a polytype of MWW and can be viewed as a disordered ABC-type stacking of MWW-layers. HRTEM and XRPD simulations show that the stacking sequence is almost random, with each layer being shifted by +/- 1/3 along the < 110 > direction with respect to the previous one. However, a small preponderance of ABAB stacking could be discerned. DNP-enhanced 2D Si-29{Si-29} J-mediated NMR analyses of calcined Si-SSZ-70 at natural Si-29 isotopic abundance (4.7%) establish the through-covalent-bond Si-29-O-Si-29 connectivities of distinct Si sites in the framework. The DNP-NMR results corroborate the presence of MWW layers and, more importantly, identify two distinct types of Q(3) silanol species at the surfaces of the interlayer regions. In the first, an isolated silanol group protrudes into the interlayer space pointing toward the pocket in the adjacent layer. In the second, the surrounding topology is the same, but the isolated -SiOH group is missing, leaving a nest of three Si-O-H groups in place of the three Si-O-Si linkages. The analyses clarify the structure of this complicated material, including features that do not exhibit long-range order. With these insights, the novel catalytic behavior of SSZ-70 can be better understood and opportunities for enhancement recognized.

  • 21.
    Smeets, Stef
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Serial electron crystallography: merging diffraction data through rank aggregation2017In: Journal of applied crystallography, ISSN 0021-8898, E-ISSN 1600-5767, Vol. 50, p. 885-892Article in journal (Refereed)
    Abstract [en]

    Serial electron crystallography is being developed as an alternative way to collect diffraction data on beam-sensitive polycrystalline materials. Merging serial diffraction data from a large number of snapshots is difficult, and the dynamical nature of electron diffraction prevents the use of existing methods that rely on precise measurement of kinematical reflection intensities. To overcome this problem, an alternative method that uses rank aggregation to combine the rankings of relative reflection intensities from a large number of snapshots has been developed. The method does not attempt to accurately model the diffraction intensity, but instead optimizes the most likely ranking of reflections. As a consequence, the problem of scaling individual snapshots is avoided entirely, and requirements for the data quality and precision are low. The method works best when reflections can be fully measured, but the benefit over measuring partial intensities is small. Since there were no experimental data available for testing rank-based merging, the validity of the approach was assessed through a series of simulated serial electron diffraction datasets with different numbers of frames and varying degrees of errors. Several programs have been used to show that these rank-merged simulated data are good enough for ab initio structure determination using several direct methods programs.

  • 22. Smeets, Stef
    et al.
    Xie, Dan
    Baerlocher, Christian
    McCusker, Lynne B.
    Wan, Wei
    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).
    Zones, Stacey I.
    High-Silica Zeolite SSZ-61 with Dumbbell-Shaped Extra-Large-Pore Channels2014In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 53, no 39, p. 10398-10402Article in journal (Refereed)
    Abstract [en]

    The synthesis of the high-silica zeolite SSZ-61 using a particularly bulky polycyclic structure-directing agent and the subsequent elucidation of its unusual framework structure with extra-large dumbbell-shaped pore openings are described. By using information derived from a variety of X-ray powder diffraction and electron microscopy techniques, the complex framework structure, with 20 Si atoms in the asymmetric unit, could be determined and the full structure refined. The Si atoms at the waist of the dumbbell are only three-connected and are bonded to terminal O atoms pointing into the channel. Unlike the six previously reported extra-large-pore zeolites, SSZ-61 contains no heteroatoms in the framework and can be calcined easily. This, coupled with the possibility of inserting a catalytically active center in the channel between the terminal O atoms in place of H+, afford SSZ-61 intriguing potential for catalytic applications.

  • 23.
    Spektor, Kristina
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nedumkandathil, Reji
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Andersson, Ove
    Häussermann, Ulrich
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Crystallization of mesoporous silica SBA-15 in a high pressure hydrothermal environment2017In: High Pressure Research, ISSN 0895-7959, E-ISSN 1477-2299, Vol. 37, no 3, p. 345-359Article in journal (Refereed)
    Abstract [en]

    Mesoporous silica SBA-15 (with similar to 6 nm pore size and similar to 6 nm wall thickness) was exposed to a hydrothermal environment at 2 and 5GPa. The p,T quenched products were investigated by powder X-ray diffraction and transmission electron microscopy. Infrared spectroscopy and thermogravimetric analysis of a sample subjected to 5GPa at room temperature suggests functionalization of both inner and outer pore surface by silanol. Partial transformation to nano-sized (20-50 nm) coesite crystals with nonfaceted morphology was observed during short equilibration times of 2h at 125 degrees C, which is significantly below the melting point of water (similar to 250 degrees C). Untransformed SBA-15 maintained intact pore structure. At 175 degrees C and during 8h, SBA-15 transformed completely into faceted coesite crystals with dimensions 100-300 nm, suggesting Ostwald ripening and thus significant mass transport in the solid water environment. At 2GPa the melting point of water is near 70 degrees C. Partial transformation to nano-sized alpha-quartz was observed at 65 degrees C and during 2h. Untransformed SBA-15 partially pore collapsed. The reduced pore stability of SBA-15 at 2GPa is attributed to the presence of liquid water in the pores due to melting point depression of confined water.

  • 24.
    Su, Jie
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Kapaca, Elina
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Liu, Leifeng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Georgieva, Veselina
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Valtchev, Valentin
    Hovmöller, Sven
    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).
    Structure analysis of zeolites by rotation electron diffraction (RED)2014In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 189, p. 115-125Article in journal (Refereed)
    Abstract [en]

    Single crystal X-ray diffraction and powder X-ray diffraction (PXRD) are powerful methods for determination of unknown crystal structures including zeolites. However, these techniques have some limitations. For instance, single crystal X-ray diffraction requires large enough crystals which are often difficult to synthesize. For powder X-ray diffraction, peak indexing and intensity extraction become difficult if there exist peak broadening caused by small crystal sizes and peak overlap due to large unit cell and high symmetry. This becomes even more complicated for samples that contain more than one phase. We developed a new rotation electron diffraction (RED) method that can overcome these limitations. Almost complete three-dimensional electron diffraction datasets can be collected from micron- or nano-sized single crystals in a transmission electron microscope by combining electron beam tilt and goniometer tilt. Here, we demonstrate the power and limitations of the RED method for ab initio structure determination of four sub-micron sized zeolites, including a calcined silicalite-1, an EUO-type germanosilicate, an FER-type aluminogermanosilicate and an AST-type aluminogermanosilicate. The latter three zeolites were found in multiphasic samples. We show how the tilt range, tilt step and resolution affect the unit cell determination, structure solution and structure refinement. The EUO-, FER- and AST-type zeolites were found in two multiphasic samples in the Al-Ge-Si system, which were also characterized by PXRD and N-2 sorption.

  • 25.
    Svengren, Henrik
    et al.
    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).
    Grins, Jekabs
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Torapava, Natallia
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Direct Synthesis of Two Inorganic Catalysts on Carbon Fibres for the Electrocatalytic Oxidation of Water2017In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 23, no 3, p. 568-575Article in journal (Refereed)
    Abstract [en]

    Two electrodes for anodic water oxidation made by direct synthesis of inorganic catalysts onto conductive carbon fibre sheets are evaluated. As catalysts two Co- and Sb-containing phases were tested, that is, Co3Sb4O6F6 and the new compound CoSbO4. The compounds express large differences in their morphology: CoSbO4 grows as thin needles whereas Co3Sb4O6F6 grows as larger facetted crystals. Despite the smaller surface area the latter compound shows a better catalytic performance. When the compound Co3Sb4O6F6 was used it gave a low increase of +0.028 mV h(-1) at an overpotential of eta = 472 mV after 10 h and a stability of +0.48 mV h(-1) at an overpotential of eta = 488 mV after 60 h. The leakages of Co and Sb were negligible and only <0.001 at% Co and approximately 0.02 at% Sb were detected in the electrolyte.

  • 26.
    Verho, Oscar
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Gao, Feifei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Johnston, Eric V.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nagendiran, Anuja
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zheng, Haoquan
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Mesoporous silica nanoparticles applied as a support for Pd and Au nanocatalysts in cycloisomerization reactions2014In: APL materials, ISSN 2166-532X, Vol. 2, no 11, p. 113316-Article in journal (Refereed)
    Abstract [en]

    Ultra-small mesoporous silica nanoparticles (MSNs) have been synthesized at room temperature with particle sizes ranging from 28 to 45 nm. These MSNs have been employed as heterogeneous supports for palladium and gold nanocatalysts. The colloidal nature of the MSNs is highly useful for catalytic applications as it allows for better mass transfer properties and a more uniform distribution of the nanocatalysts in solution. The two nanocatalysts were evaluated in the cycloisomerization of alkynoic acids and demonstrated to produce the corresponding alkylidene lactones in good to excellent yields under mild conditions. In addition to their high activity, the catalysts exhibit low degree of metal leaching and straight-forward recycling, which highlight the practical utility of MSNs as supports for nanocatalysts. (C) 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.

  • 27.
    Wan, Wei
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Hovmöller, Sven
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Structure projection reconstruction from through focus series of high resolution transmission electron microscopy images2012In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 115, p. 50-60Article in journal (Refereed)
    Abstract [en]

    A structure projection reconstruction method based on contrast transfer function correction of through-focus series of high-resolution transmission electron microscopy images is presented. In this method, defocus values are determined by evaluating phase similarities of the pixels on the Fourier transforms of the images after correction using trial defocus values. Two-fold astigmatism is also determined, by measuring focus variation along different directions. Each image in the series is corrected for the effects of contrast transfer function and then combined into a structure projection image. The method works for both crystalline and non-crystalline objects. Test results with experimental images are presented. Influences of experimental parameters for imaging and effects of crystal thickness on reconstruction are discussed.

  • 28.
    Wan, Wei
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Su, Jie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zou, Xiaodong D.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Willhammar, Tom
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Transmission electron microscopy as an important tool for characterization of zeolite structures2018In: Inorganic chemistry frontiers, ISSN 2052-1553, Vol. 5, no 11, p. 2836-2855Article in journal (Refereed)
    Abstract [en]

    Transmission electron microscopy (TEM) is an important tool for structure characterization of zeolite materials. Structural information can be obtained by different TEM techniques, for example electron diffraction (ED), high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM) and electron tomography (ET), each with its own advantages and limitations. These techniques are briefly introduced. Examples are given to show how these techniques can be used to solve various structure-related problems in zeolites. With this review we will describe the basic principles of transmission electron microscopy techniques for structural characterization, including recent methodological advancements. Advantages as well as challenges of using TEM for structural characterization will be described in relation to other methods. Examples of structural characterization of zeolites will be given for each of the methods.

  • 29.
    Wan, Wei
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Su, Jie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hovmöller, Sven
    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).
    Three-dimensional rotation electron diffraction: software RED for automated data collection and data processing2013In: Journal of applied crystallography, ISSN 0021-8898, E-ISSN 1600-5767, Vol. 46, p. 1863-1873Article in journal (Refereed)
    Abstract [en]

    Implementation of a computer program package for automated collection and processing of rotation electron diffraction (RED) data is described. The software package contains two computer programs: RED data collection and RED data processing. The RED data collection program controls the transmission electron microscope and the camera. Electron beam tilts at a fine step (0.05-0.20 degrees) are combined with goniometer tilts at a coarse step (2.0-3.0 degrees) around a common tilt axis, which allows a fine relative tilt to be achieved between the electron beam and the crystal in a large tilt range. An electron diffraction (ED) frame is collected at each combination of beam tilt and goniometer tilt. The RED data processing program processes three-dimensional ED data generated by the RED data collection program or by other approaches. It includes shift correction of the ED frames, peak hunting for diffraction spots in individual ED frames and identification of these diffraction spots as reflections in three dimensions. Unit-cell parameters are determined from the positions of reflections in three-dimensional reciprocal space. All reflections are indexed, and finally a list with hkl indices and intensities is output. The data processing program also includes a visualizer to view and analyse three-dimensional reciprocal lattices reconstructed from the ED frames. Details of the implementation are described. Data collection and data processing with the software RED are demonstrated using a calcined zeolite sample, silicalite-1. The structure of the calcined silicalite-1, with 72 unique atoms, could be solved from the RED data by routine direct methods.

  • 30. Wang, Yilin
    et al.
    Wang, Yunchen
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Su, Jie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Song, Xiaowei
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Yu, Jihong
    Interrupted silicogermanate with 10-ring channels: synthesis and structure determination by combining rotation electron diffraction and powder X-ray diffraction2017In: Inorganic Chemistry Frontiers, ISSN 2052-1553, Vol. 4, no 10, p. 1654-1659Article in journal (Refereed)
    Abstract [en]

    Silicogermanate (JU110) with an interrupted open-framework has been synthesized by using a hydrothermal method using 1,1′-(1,4-phenylenebis(methylene))bis(1-methylpyrrolidin-1-ium) hydroxide as an organic structure-directing agent (OSDA). Silicon and fluoride anions were introduced to the concentrated-gel synthesis system, and different synthetic parameters influencing the synthesis were discussed. The structure of JU110 was characterised by using rotation electron diffraction (RED) and high-resolution powder X-ray diffraction. JU110 crystallizes in the space group Fm2m (No. 42) with a = 13.9117(2) Å, b = 18.2980(3) Å and c = 32.7800(6) Å. The structure is constructed by the sti layers found in the STI framework that are pillared by D4R/Ge7 units to form a large cavity, showing 10-ring openings along [100] and 9-ring openings along [110]. Thermal stability studies showed that the framework was maintained with the loss of water molecules, but collapsed with the removal of charge-compensating cations.

  • 31.
    Wang, Yunchen
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Palatinus, Lukas
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Dynamical structure refinement of Ni3Si2 against rotation electron diffraction dataManuscript (preprint) (Other academic)
  • 32.
    Wang, Yunchen
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Takki, Sofia
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Cheung, Ocean
    Xu, Hongyi
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Öhrström, Lars
    Inge, Andrew Kentaro
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Elucidation of the elusive structure and formula of the active pharmaceutical ingredient bismuth subgallate by continuous rotation electron diffraction2017In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 53, no 52, p. 7018-7021Article in journal (Refereed)
    Abstract [en]

    Bismuth subgallate has been used in wound and gastrointestinal therapy for over a century. The combination of continuous rotation electron diffraction and sample cooling finally revealed its structure as a coordination polymer. The structure provides insight regarding its formula, poor solubility, acid resistance and previously unreported gas sorption properties.

  • 33.
    Wang, Yunchen
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Yang, Taiming
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    On the quality of the continuous rotation electron diffraction data for accurate atomic structure determination of inorganic compoundsManuscript (preprint) (Other academic)
  • 34.
    Wang, Zhengyang
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Carrillo-Cabrera, Wilder
    Gruener, Daniel
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Yin, Xiaoju
    Qiu, Shilun
    Zhu, Guangshan
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Epitaxial growth of core-shell zeolite X-A composites2012In: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 14, no 6, p. 2204-2212Article in journal (Refereed)
    Abstract [en]

    A core-shell zeolite composite consisting of a single-crystal FAU-type zeolite (zeolite X) as the core and the LTA-type zeolite (zeolite A) as the shell has been synthesized. The growth of the zeolite shell has been studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and single crystal X-ray diffraction. Cross-sections for SEM and TEM studies were prepared by argon ion cross-section polishing (CP) and focused ion beam (FIB), respectively. The results show that crystals of zeolite A grew epitaxially and uniformly on zeolite X with well-defined orientation relationships. Three possible models of the X-A interface have been proposed, all indicating that the pores in zeolites X and A are interconnected. The different techniques used for studying the composite materials are described in detail, which are general and can be applied for studying other composite materials.

  • 35.
    Willhammar, Tom
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Oleynikov, Peter
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zhang, Daliang
    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).
    Moliner, Manuel
    Gonzalez, Jorge
    Martínez, Christina
    Rey, Fernando
    Corma, Avelino
    Structure and catalytic properties of the most complex intergrown zeolite ITQ-39 determined by electron crystallography2012In: Nature Chemistry, ISSN 1755-4330, E-ISSN 1755-4349, Vol. 4, p. 188-194Article in journal (Refereed)
    Abstract [en]

    Porous materials such as zeolites contain well-defined pores in molecular dimensions and have important industrial applications in catalysis, sorption and separation. Aluminosilicates with intersecting 10- and 12-ring channels are particularly interesting as selective catalysts. Many porous materials, especially zeolites, form only nanosized powders and some are intergrowths of different structures, making structure determination very challenging. Here, we report the atomic structures of an aluminosilicate zeolite family, ITQ-39, solved from nanocrystals only a few unit cells in size by electron crystallography. ITQ-39 is an intergrowth of three different polymorphs, built from the same layer but with different stacking sequences. ITQ-39 contains stacking faults and twinning with nano-sized domains, being the most complex zeolite ever solved. The unique structure of ITQ-39, with a three-dimensional intersecting pairwise 12-ring and 10-ring pore system, makes it a promising catalyst for converting naphtha into diesel fuel, a process of emerging interest for the petrochemical industry.

  • 36. Xie, Dan
    et al.
    McCusker, Lynne B.
    Baerlocher, Christian
    Zones, Stacey I.
    Wan, Wei
    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).
    SSZ-52, a Zeolite with an 18-Layer Aluminosilicate Framework Structure Related to That of the DeNOx Catalyst Cu-SSZ-132013In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 135, no 28, p. 10519-10524Article in journal (Refereed)
    Abstract [en]

    A new zeolite (SSZ-52, vertical bar(C14H28N)(6)Na-6(H2O)(18)vertical bar[Al12Si96O216]), related to the DeNOx catalyst Cu-SSZ-13 (CHA framework type), has been synthesized using an unusual polycyclic quaternary ammonium cation as the structure-directing agent. By combining X-ray powder diffraction (XPD), high-resolution transmission electron microscopy (HRTEM) and molecular modeling techniques, its porous aluminosilicate framework structure (R (3) over barm, a = 13.6373(1) angstrom, c = 44.7311(4) angstrom), which can be viewed as an 18-layer stacking sequence of hexagonally arranged (Si,Al)(6)O-6 rings (6-rings), has been elucidated. The structure has a three-dimensional 8-ring channel system and is a member of the ABC-6 family of zeolites (those that can be described in terms of 6-ring stacking sequences) like SSZ-13, but it has cavities that are twice as large. The code SFW has been assigned to this new framework type. The large cavities contain pairs of the bulky organic cations. HRTEM and XPD simulations show that stacking faults do occur, but only at the 5-10% level. SSZ-52 has considerable potential as a catalyst in the areas of gas conversion and sequestration.

  • 37. Yang, Tao
    et al.
    Petricek, Vaclav
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Wei, Zidong
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Mullite-derivative Bi2MnxAl7-xO14 (x similar to 1): structure determination by powder X-ray diffraction from a multi-phase sample2012In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 41, no 10, p. 2884-2889Article in journal (Refereed)
    Abstract [en]

    As a supplementary method to single crystal X-ray diffraction (XRD), nowadays crystal structure determination by powder XRD has become popular, especially for those areas with difficulties getting high quality single crystals. Here we observed an intermediate phase Bi2MnxAl7-xO14 (x similar to 1) during the decomposition of mullite-Bi2MnxAl4-xO9+delta (solid solution of Bi2Mn4O10-Bi2Al4O9). As a metastable phase, it started to decompose while forming, thus no single-phase sample can be obtained. We successfully determined its structure by powder XRD from a multi-phase sample. A modified Le Bail fitting using the atomic structure information of known impurities showed a more reliable intensity extraction from a multi-phase powder XRD than that without using atomic structures for the known impurities. The charge-flipping algorithm and Monte-Carlo based simulated annealing technique were then applied to obtain the full structural model. In principle, this strategy is applicable to more complex problems, and not limited to the oxide materials. Bi2MnxAl7-xO14 possesses a mullite-related structure. There are one tetrahedral and two octahedral sites for Mn and Al, where disordering with substantial site preferences is observed. Specifically, M1O(6) and M3O(6) octahedra share edges along the c-direction with the periodicity of 1 : 2. These octahedral chains are further connected into a 3D structure through M2O(4) dimmers and Bi.

  • 38.
    Yun, Yifeng
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hernandez, Manuel
    Wan, Wei
    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).
    Jorda, Jose L.
    Cantin, Angel
    Rey, Fernando
    Corma, Avelino
    The first zeolite with a tri-directional extra-large 14-ring pore system derived using a phosphonium-based organic molecule2015In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 51, no 36, p. 7602-7605Article in journal (Refereed)
    Abstract [en]

    A new germanosilicate zeolite (denoted as ITQ-53) with extra-large pores has been synthesised using tri-tertbutylmethylphosphonium cation as the organic structure directing agent (OSDA). Rotation electron diffraction (RED) was used to identify ITQ-53 from an initially-synthesised sample containing impurities, and to solve its structure. The structure was refined against PXRD data of pure ITQ-53 samples obtained after synthesis optimisation. ITQ-53 is the first example of extra-large pore zeolites with tri-directional interconnected 14 x 14 x 14-ring channels. It is stable up to at least 650 degrees C. The structure of ITQ-53 changes from monoclinic to orthorhombic upon calcination.

  • 39.
    Yun, Yifeng
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hernández, Manuel
    Wan, Wei
    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).
    Jordá, Jose L.
    Cantín, Angel
    Rey, Fernando
    Corma, Avelino
    The first zeolite with a tri-directional extra-large 14-ring pore system derived using a phosphonium-based organic moleculeManuscript (preprint) (Other academic)
    Abstract [en]

    A new germanosilicate zeolite (denoted as ITQ-53) with extra-large 14-ring pores has been synthesized using tri-tertbutylmethylphosphonium cation as the organic structure directing agent (OSDA). The new rotation electron diffraction (RED) method was used to both identify and solve the structure of ITQ-53 from an initially synthesized sample containing impurities, which facilitated the synthesis optimization that led to pure ITQ-53. The structure was refined against PXRD data. ITQ-53 is the first example of extra-large pore zeolites with tri-directional interconnected 14 × 14 × 14-ring channels. It is built from double 3-rings (D3Rs), double 4-rings (D4Rs), and a new composite building unit [42.54.63]. D3Rs are very rare, previously only found in two zeolitic silicogermanates. ITQ-53 is stable up to at least 450 °C. The structure of ITQ-53 was changed from monoclinic to orthorhombic up on calcination.

  • 40.
    Yun, Yifeng
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Rabbani, Faiz
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Su, Jie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Xu, Hongyi
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hovmöller, Sven
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Johnsson, Mats
    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).
    Phase identification and structure determination from multiphase crystalline powder samples by rotation electron diffraction2014In: Journal of applied crystallography, ISSN 0021-8898, E-ISSN 1600-5767, Vol. 47, p. 2048-2054Article in journal (Refereed)
    Abstract [en]

    Phase identification and structure characterization are important in synthetic and materials science. It is difficult to characterize the individual phases from multiphase crystalline powder samples, especially if some of the phases are unknown. This problem can be solved by combining rotation electron diffraction (RED) and powder X-ray diffraction (PXRD). Four phases were identified on the same transmission electron microscopy grid from a multiphase sample in the Ni-Se-O-Cl system, and their structures were solved from the RED data. Phase 1 (NiSeO3) was found in the Inorganic Crystal Structure Database using the information from RED. Phase 2 (Ni3Se4O10Cl2) is an unknown compound, but it is isostructural to Co3Se4O10Cl2, which was recently solved by single-crystal X-ray diffraction. Phase 3 (Ni5Se6O16Cl4H2) and Phase 4 (Ni5Se4O12Cl2) are new compounds. The fact that there are at least four different compounds in the as-synthesized material explains why the phase identification and structure determination could not be done by PXRD alone. The RED method makes phase identification from such multiphase powder samples much easier than would be the case using powder X-ray diffraction. The RED method also makes structure determination of submicrometre-sized crystals from multiphase samples possible.

  • 41.
    Yun, Yifeng
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Rabbani, Faiz
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Su, Jie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Xu, Hongyi
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Hovmöller, Sven
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Phase identification and structure determination from multiphasic crystalline powder samples by rotation electron diffractionIn: Journal of applied crystallography, ISSN 0021-8898, E-ISSN 1600-5767Article in journal (Refereed)
    Abstract [en]

    Phase identification and structure characterisation are important in synthetic and material science. It is difficult to characterise the individual phases from multiphasic crystalline powder samples, especially if some of the phases are unknown. Here we describe how this problem can be solved by combining rotation electron diffraction (RED) and powder X-ray diffraction (PXRD). Four phases were identified on the same transmission electron microscopy (TEM) grid from a multiphasic sample in the Ni-Se-O-Cl system and their structures were solved from the RED data. Phase 1 (NiSeO3) was found in the Inorganic Crystal Structure Data (ICSD) database using the information from RED. Phase 2 (Ni3Se4O10Cl2) is an unknown compound but it is iso-structural to Co3Se4O10Cl2, which was recently solved by single crystal X-ray diffraction. Phase 3 (Ni5Se6O16Cl4H2) and Phase 4 (Ni5Se4O12Cl2) are new compounds. The fact that there are at least four different compounds in the as-synthesised material explains why the phase identification and structure determination could not be done only by PXRD. The RED method makes phase identification from such multiphasic powder samples much easier compared to powder X-ray diffraction. The RED method also makes structure determination of submicron-sized crystals from multiphasic samples possible.

  • 42.
    Yun, Yifeng
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Willhammar, Tom
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Burton, Allen
    Strohmaier, Karl G.
    Terefenko, Gene
    Vroman, Hilda
    Afeworki, Mobae
    Cheng, Jane
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Rational synthesis and structure of a borosilicate zeolite with intersecting 10- and 11-ring channelsManuscript (preprint) (Other academic)
  • 43.
    Yun, Yifeng
    et al.
    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).
    Hovmöller, Sven
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Three-dimensional electron diffraction as a complementary technique to powder X-ray diffraction for phase identification and structure solution of powders2015In: IUCrJ, ISSN 2052-2525, Vol. 2, p. 267-282Article in journal (Refereed)
    Abstract [en]

    Phase identification and structure determination are important and widely used techniques in chemistry, physics and materials science. Recently, two methods for automated three-dimensional electron diffraction (ED) data collection, namely automated diffraction tomography (ADT) and rotation electron diffraction (RED), have been developed. Compared with X-ray diffraction (XRD) and two-dimensional zonal ED, three-dimensional ED methods have many advantages in identifying phases and determining unknown structures. Almost complete three-dimensional ED data can be collected using the ADT and RED methods. Since each ED pattern is usually measured off the zone axes by three-dimensional ED methods, dynamic effects are much reduced compared with zonal ED patterns. Data collection is easy and fast, and can start at any arbitrary orientation of the crystal, which facilitates automation. Threedimensional ED is a powerful technique for structure identification and structure solution from individual nano-or micron-sized particles, while powder X-ray diffraction (PXRD) provides information from all phases present in a sample. ED suffers from dynamic scattering, while PXRD data are kinematic. Three-dimensional ED methods and PXRD are complementary and their combinations are promising for studying multiphase samples and complicated crystal structures. Here, two three-dimensional ED methods, ADTand RED, are described. Examples are given of combinations of three-dimensional ED methods and PXRD for phase identification and structure determination over a large number of different materials, from Ni-Se-O-Cl crystals, zeolites, germanates, metal-organic frameworks and organic compounds to intermetallics with modulated structures. It is shown that three-dimensional ED is now as feasible as X-ray diffraction for phase identification and structure solution, but still needs further development in order to be as accurate as X-ray diffraction. It is expected that three-dimensional ED methods will become crucially important in the near future.

  • 44.
    Zhang, Daliang
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Grüner, Daniel
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Oleynikov, Peter
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hovmöller, Sven
    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).
    Precession Electron Diffraction Using a Digital Sampling Method2010In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 211, no 1, p. 47-55Article in journal (Refereed)
    Abstract [en]

    A software-based method for collecting precession electron diffraction (PED) patterns isdescribed. The PED patterns are obtained on a computer controlled transmission electronmicroscope. A series of electron diffraction (ED) patterns are collected as still ED frames atequal intervals while the electron beam is precessed by one period (360°) around the opticalaxis. A PED pattern is obtained by combining the different ED frames, which resembles thesampling of a conventional PED pattern. Since intermediate ED frames are collected, it ispossible to perform different post-processing strategies on the ED data. This can be used forgeometric corrections to obtain accurate integrated intensities. The alignments and datacollection are fully automated and controlled by software. The data quality is comparable towhat can be achieved using specialized hardware for precession. The PED data can be usedfor structure solution and refinement with reasonably good R-values.

  • 45.
    Zheng, Haoquan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zhang, Yuning
    Liu, Leifeng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Guo, Peng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Nyström, Andreas M.
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    One-pot Synthesis of Metal Organic Frameworks with Encapsulated Target Molecules and Their Applications for Controlled Drug Delivery2016In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 138, no 3, p. 962-968Article in journal (Refereed)
    Abstract [en]

    Many medical and chemical applications require target molecules to be delivered in a controlled manner at precise locations. Metal-organic frameworks (MOFs) have high porosity, large surface area, and tunable functionality and are promising carriers for such purposes. Current approaches for incorporating target molecules are based on multistep postfunctionalization. Here, we report a novel approach that combines MOF synthesis and molecule encapsulation in a one-pot process. We demonstrate that large drug and dye molecules can be encapsulated in zeolitic imidazolate framework (ZIF) crystals. The molecules are homogeneously distributed within the crystals, and their loadings can be tuned. We show that ZIF-8 crystals loaded with the anticancer drug doxorubicin (DOX) are efficient drug delivery vehicles in cancer therapy using pH-responsive release. Their efficacy on breast cancer cell lines is higher than that of free DOX. Our one-pot process opens new possibilities to construct multifunctional delivery systems for a wide range of applications.

  • 46.
    Zou, Xiaodong
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Hovmöller, Sven
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Quantitative 3D electron microscopy and 3D electron diffraction2010In: Journal of Chinese Electron Microscopy Society, Vol. 29, p. 230-243Article in journal (Refereed)
    Abstract [en]

    Electron crystallography can be used for determination of atomic structures of micrometer-/ nanometer-sized crystals, which are million times smaller than those required by X-ray crystallography. Structure determination at atomic resolution can be done from both high-resolution electron microscopy images combined with crystallographic image processing and electron diffraction data, or by combining them with powder X-ray diffraction data. Atoms may be overlapped in all projections if the unit cell of the crystal is large. In such cases, atomic structures can be obtained by collecting several diffraction patterns and images from different directions and combining them to reconstruct a three-dimensional potential map. In this paper, some recent developments of electron crystallography and its applications in structure determination of inorganic crystals in the past decade are shown.

     

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