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Method for reconstructing crystal Bravais lattice by using electron diffraction pattern

A technology of electron diffraction and Bravais, applied in the direction of material analysis, measuring devices, instruments, etc. using wave/particle radiation, can solve problems such as crystal determination with low symmetry

Active Publication Date: 2021-01-12
MINZU UNIVERSITY OF CHINA
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Obviously, in the growing research on nanomaterials, it is difficult to realize crystals with small grains and low symmetry using conventional transmission electron microscopes, especially high-resolution transmission electron microscopes (small objective lens pole piece, tilt angle <±25°). Determining the Bravais lattice

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  • Method for reconstructing crystal Bravais lattice by using electron diffraction pattern
  • Method for reconstructing crystal Bravais lattice by using electron diffraction pattern
  • Method for reconstructing crystal Bravais lattice by using electron diffraction pattern

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0068] Embodiment 1 Measures the Bravais lattice of monocrystalline silicon

[0069] 1) Record a selected area electron diffraction pattern with high-order Laue diffraction of single crystal silicon; figure 2 a is the belt-axis electron diffraction of single crystal silicon recorded by JEOLJEM-2100 transmission electron microscope at 200kV, and the camera length L=100mm.

[0070] 2) Measure the two-dimensional primordial cell on zero-order Laue diffraction

[0071] Taking the transmission spot as the origin O of the two-dimensional primitive cell, and taking the nearest neighbor diffraction points A and B as the adjacent sides to construct the two-dimensional primitive cell, as figure 2 as shown in b. Measure OA, OB and ∠AOB, and the measurement results are listed in Table 1.

[0072] 3) Measure the high-order Laue diffraction ring, according to the formula CH=R 2 / (2λL 2 ) (where R is the radius of the high-order Laue diffraction ring, is the wavelength of the 200kV ...

Embodiment 2

[0091] Embodiment 2 measures the Bravais lattice of titanium dioxide

[0092] 1) Record a selected-area electron diffraction pattern with high-order Laue diffraction of titanium dioxide; image 3 a is the belt-axis electron diffraction of titanium dioxide recorded by a JEOLJEM-2100 transmission electron microscope at 200kV, and the camera length L=100mm. This electron diffraction is not strictly a band-axis electron diffraction, and deviates from the positive band axis by about 0.11°.

[0093] 2) Measure the two-dimensional primordial cell on zero-order Laue diffraction

[0094] Taking the transmission spot as the origin O of the two-dimensional primitive cell, and taking the nearest neighbor diffraction points A and B as the adjacent sides to construct the two-dimensional primitive cell, as image 3 as shown in b. Measure OA, OB and ∠AOB, and the measurement results are listed in Table 2.

[0095] 3) Measure the high-order Laue diffraction ring, according to the formula C...

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Abstract

The invention relates to a method for reconstructing a Bravais lattice of a crystal by using an electron diffraction pattern. The method comprises the following steps of: 1) recording a zone-axis electron diffraction pattern of a crystal to be detected to obtain a zone-axis electron diffraction pattern containing high-order Laue diffraction; 2), measuring a two-dimensional primitive cell; 3) measuring a high-order Laue diffraction ring; 4) measuring a high-order Laue diffraction point; 5), reconstructing a three-dimensional reciprocal primitive cell; 6) converting the reciprocal primitive cells obtained in the step 5) into positive grids; 7), performing reduction processing; and 8), converting the Niggli reduced cells into the Bravais lattice. According to the method, the lattice type andthe lattice constant of the measured crystal can be analyzed only by one zone-axis electron diffraction pattern containing high-order Laue diffraction points; in actual electron microscope experimentsand data analysis, the workload of the experiments and analysis can be greatly reduced.

Description

technical field [0001] The invention relates to a method for reconstructing a Bravais lattice of a crystal by using an electron diffraction pattern, and belongs to the technical field of material microstructure characterization and crystal structure analysis. Background technique [0002] The type and size of Bravais lattices are necessary parameters for crystal structure elucidation using X-ray diffraction and electron diffraction. For powder samples with good crystallinity and a single phase, the Bravais lattice can be obtained by indexing the measured diffraction peaks using X-ray diffraction technology. However, in materials with multiple phases or poor crystallization, it is difficult to accurately determine the Bravais lattice of each phase because it is difficult to accurately extract the diffraction peaks of each phase. [0003] The advantage of transmission electron microscopy is that it can perform selected area electron diffraction or nanobeam diffraction on a si...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N23/20058G01N23/2055
CPCG01N23/20058G01N23/2055
Inventor 施洪龙
Owner MINZU UNIVERSITY OF CHINA