Method for determining unknown crystal Bravais lattice by electric back scattering diffraction

Abstract

The invention provides a method used for determining Bravais lattice of unknown crystal by electron backscatter diffraction. The invention is characterized in that the method comprises the steps as follows: 1) an electron backscatter diffraction spectrum is obtained and the crystal diffraction information in the diffraction spectrum is measured; 2) a two-dimensional reciprocal surface of the crystal is obtained; 3) a three-dimensional reciprocal primitive cell is reconstructed by the two-dimensional reciprocal surface; 4) the cell parameter of the three-dimensional reciprocal primitive cell s worked out according to the width of the Kikuchi band and the angle between the Kikuchi bands in the same Kikuchi electrode; 5) a reciprocal reduced cell of the crystal is solved; 6) the Bravais lattice of the crystal is determined in the reciprocal space; 7) the Bravais lattice of the crystal is determined. In the method, only a scanning electron microscope and an electron backscatter diffraction accessory are used to realize the analysis on unknown lattice of bulk crystals, and the exponential of the Kikuchi band and the Kikuchi electrode in the electron backscatter diffraction spectrum is marked at the same time. The method has no special requirement on the samples to be analyzed, is suitable for quickly analyzing bulk samples, and can be used for analyzing the microstructure morphologies and crystal structure in the buck samples.

Description

technical field [0001] The invention provides a method for determining the Bravais lattice of an unknown crystal by electron backscatter diffraction, and belongs to the technical field of material microstructure characterization and crystal structure analysis. Background technique [0002] The existing methods for determining the Bravais lattice of unknown crystals mainly include X-ray diffraction and electron diffraction. The former uses an X-ray diffractometer to scan the sample, and a typical X-ray diffraction spectrum contains information on the interplanar spacing and diffraction intensity. , but the three-dimensional crystallographic information such as the angle between crystal planes is lost. This method is suitable for analyzing bulk and powder samples. The measurement accuracy of crystal plane spacing is relatively high, but the diffraction intensity is affected by factors such as material texture. For samples with unknown structure, the chemical composition of the...

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Problems solved by technology

[0004] It should be pointed out that the electron backscatter diffraction technique on the scanning electron microscope is currently mainly used to determine the orientation of known crystals and identify the phases inside the material. The so-called phase identification here refers to the analysis of materials by means of energy spectroscopy and other measurement methods. Chemical composition, or the constituent elements of known materials, list possible phase structures according to the chemical composition, and then try to calibrate the electron backscattered diffraction spectrum among these candidate structures, and use the exclusion method to finally determine the phase to be analyzed. The Bravais lattice of an unknown crystal cannot be determined by phase discrimination methods when the chemical composition is known

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