Backscattered Electron Energy Analysis for Phase Differentiation
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Solution Overview
Problem
Conventional electron backscatter diffraction methods struggle to accurately distinguish crystalline phases in samples with the same crystal lattice due to similar Kikuchi band thicknesses, limiting the differentiation of phases based on EBSD patterns alone.
Innovation Solution
Utilizing direct charged particle detectors to directly count the number and measure the energy of backscattered electrons, determining statistical electron characteristics and energy spectra to identify phase characteristics, and comparing these characteristics with reference data for accurate phase assignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional indirect electron detectors using scintillators are used to detect backscattered electrons, then the detector can convert electrons to photons for imaging, but the detector cannot directly count or measure the energies of backscattered electrons, limiting phase differentiation capability
Solution Approach 1:
The patent replaces the indirect scintillator-based detection system with a direct electron counting detector. This substitution enables direct measurement of electron counts and energy spectra, preserving information that was previously lost in the conversion process. The direct detector counts individual backscattered electrons and measures their energies without converting to photons, thereby resolving the contradiction between detection capability and information preservation.
2Device complexity
If EBSD patterns alone are used to distinguish crystalline phases, then the analysis is simple, but phases with the same crystal lattice cannot be accurately distinguished due to similar Kikuchi band thicknesses
Solution Approach 1:
The patent adds a new dimension to phase identification by incorporating electron count statistics and energy spectrum analysis alongside traditional EBSD pattern analysis. Instead of relying solely on Kikuchi band geometry (2D pattern analysis), the method utilizes the energy dimension (electron energy spectra) and statistical dimension (electron count distributions) to differentiate phases with identical crystal structures, thereby improving identification accuracy without excessive complexity increase.
3Measurement precision
If direct charged particle detectors are used to count and measure backscattered electrons, then phase characteristics can be accurately identified, but the device complexity and data processing requirements increase
Solution Approach 1:
The patent designs a detector system that performs multiple functions simultaneously: it detects backscattered electrons for EBSD pattern formation, counts individual electrons for statistical analysis, and measures electron energies for spectrum analysis. This multi-functional approach consolidates what would otherwise require separate detection systems, reducing overall device complexity while maintaining high measurement precision for phase characteristic identification.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables fast and reliable differentiation of crystalline phases by leveraging elemental composition and crystal orientation, enhancing the precision of EBSD analysis and refining indexing in techniques like 4D scanning transmission electron microscopy and transmitted Kikuchi diffraction.
Implementation Method 1
Electron backscatter diffraction is a well-known technique for characterising the crystallographic structure of samples. An electron beam incident on a sample interacts with atoms of the sample, causing the electrons to be scattered at varying angles as they leave the sample.
Implementation Method 2
An electron beam incident on a sample interacts with atoms of the sample, causing the electrons to be scattered at varying angles as they leave the sample.
Data Source
Figure 1a~1c
Figure 2a~2b
Figure 3
AI summary
There is described a method of identifying phase characteristics of a sample. The method comprises obtaining backscattered electron data of the sample using a direct charged particle detector. The direct charged particle detector comprises an array of pixels and is configured to count the number of backscattered electrons, or to measure the energy of each backscattered electron, detected by each pixel of the array when an electron beam is incident upon the sample. The backscattered electron data comprises data sets, each data set comprising the number of, or the measured energies of, the backscattered electrons detected by each pixel of the array when the electron beam is incident upon a respective region of the sample. The method further comprises determining, for each data set, a respective statistical electron characteristic or a respective electron energy spectrum, and identifying a respective phase characteristic for at least some of the regions of the sample, based on the determined statistical electron characteristics or the determined electron energy spectra. A system for identifying phase characteristics in a sample is also described.