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  • 1. Corma, Averlino
    et al.
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Hovmöller, Sven
    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.
    Sun, Junliang
    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.
    Jordá, José L.
    Díaz Cabañas, María J.
    Cantín, Ángel
    Moliner, Manuel
    Synthesis and structure of polymorph B of zeolite Beta2008In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 20, no 9, p. 3218-3223Article in journal (Refereed)
    Abstract [en]

    It was found that either polymorph B or polymorph C of zeolite beta can be obtained from the same structure directing agent: 4,4-dimethyl-4-azonia-tricyclo[5.2.2.02,6]undec-8-ene hydroxide. The synthesis occurs through a consecutive process where polymorph B is first formed and then transformed into polymorph C. It is possible to produce a zeolite highly enriched in polymorph B, provided that the transformation of this phase into polymorph C is slowed down up to the point where polymorph C is only detected at trace levels. The structure of polymorph B was determined for the first time by electron crystallography with SAED and HRTEM from areas of unfaulted polymorph B crystals.

  • 2. Han, Yu
    et al.
    Zhang, Daliang
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Chng, Leng Leng
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Zhao, Lan
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Ying, Jackie Y.
    A tri-continuous mesoporous material IBN-9 with the silica pore wall following a hexagonal minimal surface2009In: Nature Chemistry, ISSN 1755-4349, Vol. 1, p. 123-127Article in journal (Refereed)
    Abstract [en]

    Ordered porous materials with unique pore structures and pore sizes in the mesoporous range (2–50 nm) have many applications in catalysis, separation and drug delivery. Extensive research has resulted in mesoporous materials with onedimensional, cage-like and bi-continuous pore structures. Three families of bi-continuous mesoporous materials have been made, with two interwoven but unconnected channels, corresponding to the liquid crystal phases used as templates. Here we report a three-dimensional hexagonal mesoporous silica, IBN-9, with a tri-continuous pore structure that is synthesized using a specially designed cationic surfactant template. IBN-9 consists of three identical continuous interpenetrating channels, which are separated by a silica wall that follows a hexagonal minimal surface. Such a tri-continuous mesostructure was predicted mathematically, but until now has not been observed in real materials.

    Keywords: mesoporous structure, electron microscopy, self-assembly

  • 3.
    Oleynikov, Peter
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Gruner, Daniel
    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).
    Sun, Junliang
    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.
    Hovmöller, Sven
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Quantitative electron diffraction for crystal structure determination2009In: Electron crystallography for materials research and quantitative characterization of nanostructured materials / [ed] P. Moeck, S.Hovmoeller, S. Nicolopoulos, S.rouvimov, V.Petkov,M.Gateshki, P.Fraundorf, 2009, p. GG01-04Conference paper (Refereed)
    Abstract [en]

    We present a quantitative investigation of data quality using electron precession, compared to standard selected-area electron diffraction (SAED). Data can be collected on a CCD camera and automatically extracted by computer. The critical question of data quality is addressed – can electron diffraction data compete with X-ray diffraction data in terms of resolution, completeness and quality of intensities?

     

     

  • 4.
    Sun, Junliang
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Bonneau, Charlotte
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Cantin, Angel
    Corma, Avelino
    Diaz-Cabanas, Maria J.
    Moliner, Manuel
    Zhang, Daliang
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Li, Mingrun
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    The ITQ-37 mesoporous chiral zeolite2009In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 458, no 7242, p. 1154-1157Article in journal (Refereed)
    Abstract [en]

    The synthesis of crystalline molecular sieves with pore dimensions that fill the gap between microporous and mesoporous materials is a matter of fundamental and industrial interest(1-3). The preparation of zeolitic materials with extralarge pores and chiral frameworks would permit many new applications. Two important steps in this direction include the synthesis(4) of ITQ-33, a stable zeolite with 18 x 10 x 10 ring windows, and the synthesis(5) of SU-32, which has an intrinsically chiral zeolite structure and where each crystal exhibits only one handedness. Here we present a germanosilicate zeolite (ITQ-37) with extralarge 30-ring windows. Its structure was determined by combining selected area electron diffraction ( SAED) and powder X-ray diffraction (PXRD) in a charge-flipping algorithm(6). The framework follows the SrSi2 (srs) minimal net(7) and forms two unique cavities, each of which is connected to three other cavities to form a gyroidal channel system. These cavities comprise the enantiomorphous srs net of the framework. ITQ-37 is the first chiral zeolite with one single gyroidal channel. It has the lowest framework density (10.3 T atoms per 1,000 angstrom(3)) of all existing 4-coordinated crystalline oxide frameworks, and the pore volume of the corresponding silica polymorph would be 0.38 cm(3) g(-1).

  • 5.
    Sun, Junliang
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Bonneau, Charlotte
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Structural Chemistry.
    Cantín, Á
    Corma, A
    Díaz-Cabanas, M.J
    Moliner, M
    Zhang, Daliang
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Li, Mingrun
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Structural Chemistry.
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    The ITQ-37 mesoporous chiral zeolite2009In: Nature, Vol. 458, p. 1154-1157Article in journal (Refereed)
    Abstract [en]

    The synthesis of crystalline molecular sieves with pore dimensions that fill the gap between microporous and mesoporous materials is a matter of fundamental and industrial interest. The preparation of zeolitic materials with extralarge pores and chiral frameworks would permit many new applications. Two important steps in this direction include the synthesis of ITQ-33, a stable zeolite with 18 × 10 × 10 ring windows, and the synthesis of SU-32, which has an intrinsically chiral zeolite structure and where each crystal exhibits only one handedness. Here we present a germanosilicate zeolite (ITQ-37) with extralarge 30-ring windows. Its structure was determined by combining selected area electron diffraction (SAED) and powder X-ray diffraction (PXRD) in a charge-flipping algorithm. The framework follows the SrSi2 (srs) minimal net and forms two unique cavities, each of which is connected to three other cavities to form a gyroidal channel system. These cavities comprise the enantiomorphous srs net of the framework. ITQ-37 is the first chiral zeolite with one single gyroidal channel. It has the lowest framework density (10.3 T atoms per 1,000 Å3) of all existing 4-coordinated crystalline oxide frameworks, and the pore volume of the corresponding silica polymorph would be 0.38 cm3 g-1.

    Keywords: srs-net, powder X-ray, charge flipping, electron microscopy

  • 6.
    Sun, Junliang
    et al.
    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.
    He, Zhanbing
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Hovmöller, Sven
    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.
    Gramm, Fabian
    Baerlocher, Christian
    McCusker, Lynne B.
    Structure determination of zeolites by electron crystallography2008In: EMC 2008 14th European Microscopy Congress 1–5 September 2008, Aachen, Germany: 1, Instrumentation and methods / [ed] Martina Luysberg, Karsten Tillmann and Thomas Weirich, Berlin Heidelberg: Springer , 2008, p. 757-758Conference paper (Refereed)
    Abstract [en]

    Many zeolite structures have remained unsolved for a long time because of their structural complexity, the size of the crystallites or the presence of defects or impurities. By combining electron microscopy and X-ray powder diffraction data, some of them have been solved (e.g. the high-silica zeolite IM-5, which was first reported in 1998 [1] and recently solved using a charge-flipping structure solution algorithm [2] ), while for other zeolites, good X-ray powder diffraction data are hard to obtain (e.g. polymorph A or B of zeolite Beta). Here we demonstrate a complete structure determination of IM-5 (one of the most complicated zeolited) and polymorph B of zeolite Beta [3] using electron crystallography alone. This shows the power and advantage of structure determination by electron microscopy compared with the X-ray diffraction techniques. The method is general and can be applied to both zeolites and other materials, where the crystals are too small or the structure too complicated to be solved from X-ray powder diffraction data alone [4] . It is particularly useful for structures containing defects.

  • 7.
    Sun, Junliang
    et al.
    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).
    Extensive inspection of an unconventional mesoporous material at all length scales2010In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 23, no 2, p. 229-238Article in journal (Refereed)
    Abstract [en]

    The structure of an unconventional mesoporous material, formed by the packing of silica coated spherical micelles as hard spheres, has been uniquely determined through a series of advanced characterization techniques. The synchrotron-based small-angle X-ray scattering (SAXS) analysis confirms that the bulk material assembled via the hard sphere packing (HSP) route exhibits a strong 200 reflection and a relatively weaker 111 reflection, which is the first example in all reported mesostructured materials with the same symmetry. At the morphological macroscale, high-resolution scanning electron microscopy (SEM) images directly show that the hexagonal platelike micrometer-sized particles consist of nanospheres (20 nm in diameters) in a close packing mode. The intrinsic pore structure of calcined HSP material has been reconstructed using both electron crystallography (EC) and electron tomography (ET) techniques, which can be simply viewed as a face-centered cubic (fcc) packing of monodispersed hollow silica nanospheres. The EC technique provides a three-dimensional visualization of the pore organization and demonstrates the existence and crystallographic positions of the cagelike mesopores, octahedral and tetrahedral cavities. The ET method directly and accurately determines the sizes of the mesopores and octahedral cavity and offers nanometer-scale structural information at any given local area, which cannot be obtained by conventional transmission electron microscopy (TEM). To our knowledge, this is the first time that the EC and ET techniques are simultaneously employed and provide complementary information for the mesostructure determination. More importantly, the structural details collected from the synchrotron SAXS, high resolution SEM, EC and ET techniques are consistent and support the HSP mechanism, different from the well-understood liquid crystal templating or cooperative self-assembly pathways. The complex pore structure and the existence of octahedral and tetrahedral cavities are responsible for the unusual indexation of the SAXS, which is further validated by the structural simulation. Our work provides both a comparative and comprehensive case study to show the strength and limitation of individual techniques and demonstrates the need for the careful characterization of novel structures by a selection of complementary, state-of-the-art methods which provide selective structural information at different length scales.

  • 8.
    Zhang, Daliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    3D Electron crystallography: Real space reconstruction and reciprocal space tomography2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Electron crystallography is an important technique for studying micro- and nano-sized materials. It has two important advantages over X-ray crystallography for structural studies: 1) crystals millions of times smaller than those needed for X-ray diffraction can be studied; 2) it is possible to; focus the electrons to form an image. The local atomic arrangement can be seen directly by high-resolution transmission electron microscopy (HRTEM). The crystallographic structure factor phases, which are lost in recording diffraction patterns, are present in HRTEM images and can be determined experimentally. The main disadvantages of electron crystallography compared to X-ray diffraction are that the data are difficult to collect, often incomplete and suffer from dynamic scattering. New methods need to be developed to overcome these problems. In this work, structure determination of several unique and complex porous materials including zeolites and mesoporous silica is demonstrated. None of the structures of these materials could be solved by X-ray crystallography. New techniques are also developed in order to overcome the disadvantages of electron crystallography. The new techniques include a digital sampling method for collecting precession electron diffraction data and a rotation method for automatic collection of complete 3D electron diffraction data. A number of practical issues concerning data collection and data processing are described and the data quality is analysed.

  • 9.
    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.

  • 10.
    Zhang, Daliang
    et al.
    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).
    Kremer, R.K.
    Two New Layered Oxohalides in the System Cu-Yb-Te-O-Cl2010In: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 12, p. 536-540Article in journal (Refereed)
    Abstract [en]

    Two complex lanthanide(III) transition metal(II) tellurium(IV) oxyhalides, Cu3Yb2(TeO3)4Cl4 and Cu3Yb3(TeO3)4Cl6 have been synthesized and the crystal structures were determined by single-crystal X-ray diffraction. Both compounds are layered with only weak connections in between the layers. The layers are made up of [YbO8], [TeO3] and [CuOxCly] polyhedra. In both compounds the strong Lewis acid cations Yb3+ and Te4+ only form bonds to oxygen while Cu2+ form bonds to both oxygen and chlorine. This leads the Cl ions to be expelled from the bonding volumes of the crystal structures and protrude from the layers. Magnetic susceptibility measurements were performed on a powder sample of Cu3Yb2(TeO3)4Cl4. The Curie–Weiss law found at low temperatures indicates a Curie–Weiss temperature of ca. −5(1) K. However, indication for long-range magnetic ordering could not be observed down to 1.87 K. The two new phases are to the best of our knowledge the first containing all three of Cu, Yb and Te.

     

     

     

     

  • 11.
    Zhang, Daliang
    et al.
    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).
    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).
    Collecting 3D electron diffraction data by the rotation method2010In: Zeitschrift fur Kristallographie, ISSN 0044-2968, Vol. 225, no 2-3, p. 94-102Article in journal (Refereed)
    Abstract [en]

    A new method for collecting complete three-dimensional electron diffraction data is described. Diffraction data is collected by combining electron beam tilt at many very small steps, with rotation of the crystal in a few but large steps. A number of practical considerations are discussed, as well as advantages and disadvantages compared to other methods of collecting electron diffraction data.

1 - 11 of 11
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