Refinement of crystal structural parameters and charge density using convergent-beam electron diffraction – the rhombohedral phase of LaCrO<sub>3</sub>

Tsuda, Kenji; Ogata, Yoichiro; Takagi, Kenta; Hashimoto, Takuya; Tanaka, Michiyoshi

doi:10.1107/s0108767302011686

Cited by 59 publications

(22 citation statements)

References 27 publications

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“…The conformational change between bent and extended structures suggested a "switchblade" (or jack-knife) model for affinity switching. Furthermore, similar conformational changes were observed in leukocyte beta(2) integrins, alpha(X)beta(2) and alpha(L) beta (2). However, 24 kinds of integrin heterodimers exhibit their own unique ligand-binding activities and function.…”

Section: Acta Cryst (2008) A64 C601-602mentioning

confidence: 62%

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Suzuki¹,

Iwasaki²,

Nakamura³

2008

Acta Cryst Sect A

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We find a striking distribution of inversion domains in a decagonal Al64Cu22Co14, which reveals a fractal-like, self-similar microstructure constructed by golden triangles (similar to a Sierpinski Gasket). This unique morphology of domains is confirmed to be thermodynamically stable configurations at high temperatures (> ~1200K), just below the melting temperature of the Al64Cu22Co14 compound. Details of the domain microstructure are described based on dark-field TEM imaging, convergent electron diffraction and atomic-resolution STEM. We propose that the occurrence of such self-similar domains may well be understood by concerning structural modulations extended into a hyperspace. Platinum (Pt) Palladium (Pd) nanoparticles supported on amorphous silica (SiO2) were prepared by wetness impregnation techniques at same concentrations of Pt(0.5) and Pd(0.5); 1 metallic wt %. The particle size distribution were measured as function of reaction temperature, temperatures were varied in the range of 200 -400 to evaluate the nucleation phenomena and thermal stability. In addition morphology and crystallinity under various reactor temperatures were investigated by physisorption Brunauer-EmmettTeller-(BET), X-Ray Diffraction (XRD), High Resolution Electron Microscopy (HREM) and Transmission Electron Microscopy (TEM). In this work, we observed the distribution of Pt and Pd in nanoparticles. The rational design of nanoscale structures for applications in technology increasingly relies on developing and improved understanding of processes, particularly in terms of how they contribute to the changing phase behavior of nanoscale systems. Crystal structures can be determined by X-ray, while transmission electron microscopy (TEM) is indispensable for characterization of nanocrystalline materials, because TEM is a tool that provides not only atomic resolution lattice images but also chemical information at a spatial resolution, allowing direct identification the chemistry of a single nanoparticle. Poly(heptamethylene terephthalate) (PHepT), which is one of aromatic polyesters, was synthesized, and its lamellar singlecrystals were grown isothermally, for example at 70 , from a dilute solution in 1-octanol. Nanofibers of PHepT were prepared via electro-spinning (apparatus: esprayer ES-1000 (Fuence Co., Ltd.; Tokyo, Japan)) of a solution in 1,1,1,3,3,3-hexafluoro-2-propanol. Morphology of the single crystals and that of as-spun and annealed nanofibers were investigated with a transmission electron microscope (JEOL JEM-200CS) which was operated at 200kV. Selected-area electron diffraction (SAED) of the crystals gives a well-defined N-pattern consisting of spot-like hk0 reflections, and that of a bandle of the annealed nanofibers gives a highly oriented fiber pattern. From the analysis of SAED patterns for both types of specimen, namely single crystals and nanofibers, it seems that PHepT takes an orthorhombic crystal system and its unit cell parameters are as follows: a = 1.409nm, b = 1.480nm, c (chain axis) = 3.392nm, α=β= γ=90 . In add...

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Section: Acta Cryst (2008) A64 C601-602mentioning

confidence: 62%

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Suzuki¹,

Iwasaki²,

Nakamura³

2008

Acta Cryst Sect A

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“…Their quantitative structures, however, could not be determined because of their weak diffraction intensities. To overcome the intensity problem, the structure of ZnS nano-crystals was resolved by using EF-PED (Energy-Filtered Precession Electron Diffraction) and HREM (High Resolution Electron Microscopy) utilizing a HVEM (High A structure analysis method using convergent-beam electron diffraction (CBED), which was developed by Tsuda and Tanaka [1,2], enables us to directly determine the electrostatic potential from a nanometer-scale specimen area. The electron density distribution can be also obtained from the electrostatic potential through the Poisson's equation.…”

Section: P190308 Acta Cryst (2008) A64 C604-605mentioning

confidence: 99%

“…2.The chiral indices (n, m) of the CNT are estimated from the angles and the diameters. 3.Diffraction patterns of chiral indices (n, m) were simulated using a simulation program "MBFIT" [2,3]. 4.The simulated diffraction patterns are compared with the experimental patterns.…”

Section: P190308 Acta Cryst (2008) A64 C604-605mentioning

confidence: 99%

“…After indexing and scaling, experimental structure-factor magnitudes were obtained from the patterns. These provide input to the charge-flipping algorithm [1], which works well with relatively poor-quality electron diffraction data or powder diffraction data [2], to solve the phase problem and obtain the correct crystal structure. Solutions for PED and kinematic CBED data are presented for comparison with each other and with simulations.…”

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confidence: 99%

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Poster Sessions depending on the experimental condition [1][2][3][4]. The deficient line is black and the excess line white on photograph.

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A study of structure properties of ZnS nano-crystals using electron crystallography

Kim¹,

Park²,

Park³

et al. 2008

Acta Cryst Sect A

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Poster Sessions depending on the experimental condition [1][2][3][4]. The deficient line is black and the excess line white on photograph. The deficient-excess unindexed line is black on one side and white on the other side of the line. In the present work for the first time the contrast reversal along the unindexed line is obtained. The specimens were single crystalline silicon films prepared by chemical etching of bulky crystals. The transmission electron diffraction patterns were obtained in an EG-100M electron diffraction camera at an accelerating voltage of 100kV with the primary electron beam almost parallel to [111] axis. In the obtained Kikuchi patterns the unindexed line runs along the middle line of the Kikuchi band. The deficient unindexed line in the vicinity of the strong and spot reflections changes the contrast and transforms into excess line. The experimental conditions of unindexed line contrast reversal are founded. It is shown that the contrast is reversed when unindexed line passes through or in vicinity of an intense spot reflection. The contrast reversal of unindexed line is explained within the framework of the Kikuchi patterns formation mechanism with due regard for the double Kikuchi diffraction [5] The synthesis of new nanocrystalline structures demands new rapid methods of solving their crystal structures. Our goal is real-time structure solution at the electron microscope, based on automated acquisition of three-dimensional electron diffraction data with subsequent phasing of the data set and presentation of a unit-cell potential map that displays atomic positions and even species. To achieve this we must consider: 1) translation of the specimen during automated tilting; 2) automated recognition of zone-axis orientations; 3) multiple-scattering artifacts; 4) indexing methods; 5) absolute intensity scaling of the data; 6) scaling of data collected at different orientations; and 7) the phase problem. Initially, we have focused on issues 3) through 7) following manual acquisition of three-dimensional diffraction data from a known test crystal (the MgAl2O4 spinel structure). Data was collected by two techniques, both of which minimize multiple-scattering artifacts: precession electron diffraction (PED) and kinematic convergent beam electron diffraction (CBED) using an in-column Omega energy filter. After indexing and scaling, experimental structure-factor magnitudes were obtained from the patterns. These provide input to the charge-flipping algorithm [1], which works well with relatively poor-quality electron diffraction data or powder diffraction data [2], to solve the phase problem and obtain the correct crystal structure. Solutions for PED and kinematic CBED data are presented for comparison with each other and with simulations. Further development requires automated, scripted control of specimen tilt and data acquisition.[1] G. Oszlanyi and A. Suto. Acta Cryst., A60, 134 (2004).[2] J.S. Wu, J. Spence, M. O'Keeffe, and K. Leinenweber. Nat. Mater., 5, 647 (2006 A new metastable zirconi...

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TEM Applications of EELS

Egerton

2011

Electron Energy-Loss Spectroscopy in the Electron Microscope

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Refinement of crystal structural parameters and charge density using convergent-beam electron diffraction – the rhombohedral phase of LaCrO₃

Cited by 59 publications

References 27 publications

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EM Navigator– 3D electron microscopy data navigator

A study of structure properties of ZnS nano-crystals using electron crystallography

TEM Applications of EELS

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Refinement of crystal structural parameters and charge density using convergent-beam electron diffraction – the rhombohedral phase of LaCrO3

Cited by 59 publications

References 27 publications

EM Navigator– 3D electron microscopy data navigator

EM Navigator– 3D electron microscopy data navigator

A study of structure properties of ZnS nano-crystals using electron crystallography

TEM Applications of EELS

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Refinement of crystal structural parameters and charge density using convergent-beam electron diffraction – the rhombohedral phase of LaCrO₃