Structure determination of the zeolite IM-5 using electron crystallography

Sun, Junliang; He, Zhanbing; Hovmöller, Sven; Zou, Xiaodong; Gramm, Fabian; Baerlocher, Christian; McCusker, Lynne B.

doi:10.1524/zkri.2010.1204

Cited by 41 publications

(30 citation statements)

References 37 publications

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“…Improved HRTEM images of IM-5 were later used to test the limits of electron crystallography [45]. From the systematic absences in the SAED patterns and the projections symmetries of the HRTEM images, the correct space group Cmcm was obtained.…”

Section: Im-5mentioning

confidence: 99%

Electron crystallography as a complement to X-ray powder diffraction techniques

McCusker¹,

Baerlocher²

2012

Zeitschrift für Kristallographie - Crystalline Materials

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Abstract. Electron microscopy techniques yield information for crystal structure analysis that is remarkably complementary to that obtained from X-ray powder diffraction data. Structures of polycrystalline materials that resist solution by either method alone can sometimes be solved by combining the two. For example, the intensities extracted from an X-ray powder diffraction pattern are kinematical and can be interpreted easily, while those obtained from a typical selected area electron diffraction (SAED) or precession electron diffraction (PED) pattern are at least partially dynamical and therefore more difficult to use directly. On the other hand, many reflections in a powder diffraction pattern overlap and only the sum of their intensities can be measured, while those in an electron diffraction pattern are from a single crystal and therefore well separated in space. Although the intensities obtained from either SAED or PED data are less reliable than those obtained with Xrays, they can be used to advantage to improve the initial partitioning of the intensities of overlapping reflections. However, it is the partial crystallographic phase information that can be extracted either from high-resolution transmission electron microscopy (HRTEM) images or from PED data that has proven to be particularly useful in combination with high-resolution X-ray powder diffraction data. The dual-space (reciprocal and real space) structure determination programs Focus and Superflip have been shown to be especially useful for combining the two different types of data.

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Section: Im-5mentioning

confidence: 99%

Electron crystallography as a complement to X-ray powder diffraction techniques

McCusker¹,

Baerlocher²

2012

Zeitschrift für Kristallographie - Crystalline Materials

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“…Electron crystallography has several important advantages in structure analysis of these materials; single crystal electron diffraction can be collected from micro-and nano-sized crystals and high resolution transmission electron microscopy (HRTEM) images can be obtained, from which crystallographic structure factor phase information can be extracted [2]. During the past years, several of the most complicated zeolite structures were solved by electron crystallography alone [3,4] or together with PXRD [5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Stacking disorders in zeolites and open-frameworks – structure elucidation and analysis by electron crystallography and X-ray diffraction

Willhammar¹,

Zou²

2013

Zeitschrift für Kristallographie - Crystalline Materials

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Abstract. Intergrowth and stacking disorders are often found in minerals and synthetic zeolites and inorganic openframeworks. Structure elucidation of stacking disorders in these materials have been difficult and structure solution of stacking disorders in unknown zeolites and open-frameworks has been challenging. There exist no standard methods for structure analysis of such disordered materials. In this review we present various stacking disorders and intergrowth in a number of representative zeolite families containing stacking disorders. These include zeolite beta, SSZ-26/SSZ-33, ITQ-39, ABC-6, ZSM-48, SSZ-31, UTD-1, faujasite FAU/EMT, pentasil ZSM-5/ZSM-11, ITQ-13/ITQ-34, ITQ-22/ITQ-38 etc. Stacking disorders in open-frameworks containing mixed coordinations, including titanosilicates ETS-10 and ETS-4, and the silicogermanate SU-JU-14 are also described. Various crystallographic methods used for solving disordered structures are summarized. The methods include powder X-ray diffraction (PXRD), electron diffraction, high resolution transmission electron microscopy (HRTEM), and single-crystal X-ray diffraction. Examples of model building combined with simulations of PXRD and single crystal X-ray diffraction to verify the structure models are given.

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“…Therefore, the most effective test of all such models is a comparison between the bonding charge density that they predict for a particular material and a corresponding set of accurate experimental measurements. Quantitative convergent beam electron diffraction (QCBED) is a well-matured technique for the absolute (scale and extinction free) measurement of Fourier coefficients of crystal potential (structure factors) in highly perfect crystals with small units cells [1]. Crystal potential structure factors are directly related to those of the electron density via the Mott formula and it is in the low orders that the conversion process further enhances the intrinsic precision and accuracy of QCBED.…”

mentioning

confidence: 99%

“…Many different structures including the most complicated zeolites and quasicrystal approximants have been solved by electron diffraction (ED) and high-resolution transmission electron microscopy (HRTEM) combined with crystallographic image processing. [1] Even though, electron crystallography is not widely used for structure analysis compared to X-ray diffraction. The main reasons for this are 1) dynamical scattering; 2) incomplete data and 3) the techniques are not feasible and highly skilful operators are needed.…”

mentioning

confidence: 99%

“…In this contribution we compare the obtained structure to oxides containing other transition metal ions and discuss the subject of the missing oxygen position. [1,2]. Since the first report on the "Formation of Titanium Oxide based Nanotubes" [3] this type of nano materials has been discussed intensively for its use in photocatalysis or as semiconductor electrode in dye sensitized solar cells.…”

mentioning

confidence: 99%

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DFTversusaccurate experimental measurements of charge density in aluminium

Nakashima¹,

Smith²,

Muddle³

2010

Acta Cryst Sect A

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Electron crystallography is a unique technique for structure analysis of crystals too small to be studied by single-crystal X-ray diffraction, even using a synchrotron radiation. Many different structures including the most complicated zeolites and quasicrystal approximants have been solved by electron diffraction (ED) and high-resolution transmission electron microscopy (HRTEM) combined with crystallographic image processing.[1] Even though, electron crystallography is not widely used for structure analysis compared to X-ray diffraction. The main reasons for this are 1) dynamical scattering; 2) incomplete data and 3) the techniques are not feasible and highly skilful operators are needed. The later often requires a long and hard training period. We have developed several new methods to tackle those problems. Dynamical scattering may be reduced when the incident electron beam is tilted off the zone axes. This is achieved in precession electron diffraction (PED). We have developed a new software-based method -the digital sampling method to automatically collect a series of ED frames while the electron beam is precessed.[2] Several different post-processing strategies are developed for extracting the ED data and combining them to a PED pattern. The intensity data obtained by the digital sampling method were used for structure refinement of K 2 O⋅7Nb 2 O 5 . The data quality is shown to be comparable to, and in some cases even better than that obtained using a hardware-based electron precession device. We have combined digital electron beam rotations with goniometer tilts for collecting complete 3D electron diffraction data.[3] A 3D electron diffraction dataset with an tilt range of ± 70° can be collected automatically from a nanosized crystal on a JEOL JEM2100 TEM. More than one thousand electron diffraction patterns can be collected within 1-2 hours, with a step of 0.05° -0.1° for each ED frame. There is no need for pre-alignment of the crystal. The ED patterns are combined into a 3D reciprocal lattice, from which the unit cell parameters and space group can be determined. ED intensities of all reflections can be extracted and used for structure solution and refinement. Diffuse scattering and diffraction streaks caused by crystal defects can be quantified and used for studying the defect structures in the crystals. The power of the new methods for structure analysis is demonstrated on several inorganic structures and zeolites. The automation procedure for collection of complete 3D ED data from nano-sized crystals opens new possibilities and applications of electron diffraction for structure analysis.[1] Sun J.L., He Z.B., Hovmöller S., Zou, X.D., Gramm G., Baerlocher C., McCusker, L.B. "Structure determination of zeolite IM-5 by electron crystallography" Z. Kristallogr., 2010, 225, 77 Philip.Nakashima@eng.monash.edu.auThe term "density" in density functional theory (DFT), refers to the ground state charge density, which is the basis of this and other ab initio models of predictive chemistry. Therefore, the most e...

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Structure determination of the zeolite IM-5 using electron crystallography

Cited by 41 publications

References 37 publications

Electron crystallography as a complement to X-ray powder diffraction techniques

Electron crystallography as a complement to X-ray powder diffraction techniques

Stacking disorders in zeolites and open-frameworks – structure elucidation and analysis by electron crystallography and X-ray diffraction

DFTversusaccurate experimental measurements of charge density in aluminium

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