GB/T 20724-2021Microbeam analysis—Method of thickness measurement for thin crystals by convergent beam electron diffraction (English PDF)

Foreword

This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for Standardization Work Part 1. Structure and Drafting Rules of Standardization Documents" drafted.

This document replaces GB/T 20724-2006 "Method for Determination of Thickness of Thin Crystals by Converging Beam Electron Diffraction", and GB/T 20724-2006 In contrast, except for structural adjustments and editorial changes, the main technical changes are as follows:

a) Added some terms and definitions (see Chapter 3);

b) Added requirements for instrument preparation (see 7.1);

c) Changed the steps for experimental determination in TEM mode (see 7.2.1, 7.2 of the:2006 edition);

d) An example diagram of the selected area electron diffraction pattern and its index calibration has been added (see Figure 2 in 7.2.1);

e) Added the STEM mode for acquiring convergent beam diffraction patterns (see 7.2.2);

f) The method of data measurement and calculation has been changed (see 7.3, 7.6 of the:2006 edition);

g) Changed the method of finding the thickness of thin crystals by linear fitting method (see 7.3.3, 7.3.4, Chapter 8 of the:2006 edition);

h) The requirements for the format of the experimental report have been deleted (see Chapter 9 of the:2006 edition);

i) added uncertainty analysis (see Chapter 8);

j) Changed the requirements for the content of the experimental report (see Chapter 9, Chapter 9 of the:2006 edition).

Introduction

The research and development of a large number of new materials, as well as the evaluation and control of performance characteristics, require microstructure characteristics on the micro and nano scales.

Carry out analytical determination, especially the determination of the thickness of thin crystal samples or nano-scale powders, particles and other materials. Methods for measuring the thickness of thin crystals are Several, current Converging Beam Electron Diffraction (CBED) methods can measure the relative standard deviation of the thickness of thin crystals up to To about 2%, it is a very important method in material analysis. At present, our country is analyzing and testing in scientific research institutes, colleges and universities, large enterprises and various provinces and cities.

The laboratories in the test center and other places are equipped with many transmission electron microscopes/scanning transmission electron microscopes (TEM/STEM), electron diffraction techniques.

It is widely used in the analysis and research of various materials, especially new materials and nanomaterials.

In order to standardize the method of applying the converging beam electron diffraction technique to determine the thickness of thin crystals of materials, GB/T 20724- In:2006, the standard has been implemented for more than ten years. During this period, the research level of materials, analysis technology and instruments and equipment have been greatly developed and improved.

In particular, the development and application of new materials puts forward higher requirements for microbeam analysis methods. In order to adapt to the development of my country's science and technology and industrialization Trends demand for materials science and microscopic analysis, GB/T 20724-2006 has been revised.

1 Scope

This document describes Converged Beam Electron Diffraction for Thickness Measurement of Thin Crystal Specimens Using Transmission Electron Microscopy/Scanning Transmission Electron Microscopy method.

This document is suitable for the determination of thin crystal samples with linearity ranging from tens of nanometers to hundreds of micrometers and thicknesses in the range of tens of nanometers to hundreds of nanometers. thickness.

Note: Since the thickness of thin specimens for transmission electron microscopy is often non-uniform, what is measured by the method of convergent beam diffraction is the local thickness of the specimen illuminated by the electron beam.

2 Normative references

The contents of the following documents constitute essential provisions of this document through normative references in the text. Among them, dated citations documents, only the version corresponding to that date applies to this document; for undated references, the latest edition (including all amendments) applies to this document.

GB/T 18907-2013 Microbeam Analysis and Analysis Electron Microscopy Transmission Electron Microscope Selected Area Electron Diffraction Analysis Method

GB/T 27418-2017 Evaluation and representation of measurement uncertainty

ISO 15932:2013 Microbeam analysis-Analytical electron microscopy terminology (Microbeamanalysis-Analyticalelectron microscopy-Vocabulary)

3 Terms and Definitions ISO 15932:2013 and the following

terms and definitions apply to this document.