ISO 25498

2024-11-28
ISO/DIS FDIS 25498:2024(en)
ISO/TC 202/SC 3
Secretariat: JISC
Date: 2025-01-17
Microbeam analysis — Analytical electron microscopy — — Selected
area electron diffraction
analysis using a transmission electron microscope
Analyse par microfaisceaux — Microscopie électronique analytique — Analyse par diffraction par sélection
d'aire au moyen d'un microscope électronique en transmission
FDIS stage
ISO/FDIS 25498:20xx(E2025(en)
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Published in Switzerland
ii © ISO 20xx – All rights reserved

ISO/DIS FDIS 25498:20242025(en)

iii
ISO/FDIS 25498:20xx(E2025(en)
Contents
Foreword . ⅳ
Introduction . ⅵ
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 1
4 Principle . 3
5 Reference materials . 8
6 Apparatus . 8
7 Preparation of specimens . 9
8 Procedure . 9
9 Measurement and solution of the SAED patterns . 14
10 180° ambiguity . 16
11 Uncertainty estimation . 16
Annex A (informative) Interplanar spacings of references . 20
A.1 Interplanar spacings of pure Au and Al . 20
Annex B (informative) Spot diffraction patterns of single crystals for BCC, FCC and HCP
structure . 21
B.1 Symbols and definitions . 21
B.2 Spot diffraction patterns for body-centred cubic (BCC) crystals . 21
B.3 Spot diffraction patterns for face-centred cubic (FCC) crystals . 27
B.4 Spot diffraction patterns for hexagonal close-packed (HCP) crystals. 33
Bibliography . 40

Foreword . vi
Introduction . viii
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviations . 1
4 Principle . 3
5 Reference materials . 11
6 Apparatus . 11
7 Preparation of specimens . 11
8 Procedure . 12
9 Measurement and solution of the SAED patterns . 17
10 180° ambiguity . 20
11 Uncertainty estimation . 21
iv © ISO 20xx – All rights reserved

ISO/DIS FDIS 25498:20242025(en)
Annex A (informative) Interplanar spacings of references . 25
Annex B (informative) Spot diffraction patterns of single crystals for BCC, FCC and HCP
[7]
structure . 26
Bibliography . 67

v
ISO/FDIS 25498:20xx(E2025(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
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International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of
ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
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www.iso.org/iso/foreword.htmlwww.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 202, Microbeam, Subcommittee SC 3, Analytical
electron microscopy.
This third edition cancels and replaces the second edition (ISO 25498:2018), which has been technically
revised.
The main changes are as follows:
— — Scope has been revised;
— content has been revised throughout the document.
— ISO/IEC 17025 has been moved from normative references to bibliography;
— — figure 1Figure 1 has been replaced;
— — subclauseSubclause 6.3 has been deleted;
— — subclauseSubclause 8.3.6 has been deleted, the content of 8.3.6 has been moved to 8.3.2;8.3.2;
— — subclause 9.2.5Subclause 9.2.5 has been added and the following subclause has been renumbered;
— — clause 11Clause 11 has been revised，subclauses 11.1,11.2,11.3, 11.1,11.2,11.3 and 11.411.4 have
been added;
vi © ISO 20xx – All rights reserved

ISO/DIS FDIS 25498:20242025(en)
— — subclauses B.4.1Subclauses B.4.1 and B.4.2B.4.2 have been added;
— — the bibliographyBibliography has been updated and ISO/IEC Guide 98-3 (GUM:1995) has been added.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.htmlwww.iso.org/members.html.
vii
ISO/FDIS 25498:20xx(E2025(en)
Introduction
Electron diffraction techniques are widely used in transmission electron microscopy (TEM) studies.
Applications include phase identification, determination of the crystallographic lattice type and lattice
parameters, crystal orientation and the orientation relationship between two phases, phase transformations,
habit planes and defects, twins and interfaces, as well as studies of preferred crystal orientations (texture).
While several complementary techniques have been developed, for example microdiffraction, nano-
diffraction, convergent beam diffraction and reflected diffraction, the selected area electron diffraction (SAED)
technique is the most frequently employed.
This technique allows direct analysis of small areas on thin specimens from a variety of crystalline substances.
It is routinely performed on most TEMs in the world. The SAED is also a supplementary technique for
acquisition of high-resolution images, microdiffraction or convergent beam diffraction studies. The
information generated is widely applied in studies for the development of new materials, improving structure
and/or properties of various materials as well as for inspection and quality control purpose.
The basic principle of the SAED method is described in this document. The experimental procedure for the
acquirement of SAED patterns, indexing of the diffraction patterns and determination of the diffraction
constant are specified. ISO 25498 is intended for use or reference as technical regulation for transmission
electron microscopy.
viii © ISO 20xx – All rights reserved

ISO/DIS 25498:2024(en)
DRAFT International Standard
Microbeam analysis — Analytical electron microscopy — Selected
area electron diffraction analysis using a transmission electron
microscope
1 Scope
This document specifies the method offor selected area electron diffraction (SAED) analysis using a
transmission electron microscope (TEM) to analyse thin crystalline specimens. This document applies to test
areas of micrometres and sub-micrometres in size. The minimum diameter of the selected area in a specimen
which can be analysed by this method is restricted by the spherical aberration coefficient of the objective lens
of the microscope and approaches hundredhundreds of nanometres for a modern TEM.
When the size of an analysed specimen area is smaller than thatthe spherical aberration coefficient restriction,
this document can also be used for the analysis procedure. However, because of the effect of spherical
aberration and deviation of the specimen height position, some of the diffraction information in the pattern
can be generated from outside of the area defined by the selected area aperture. In such cases, the use of
microdiffraction (nano-beam diffraction) or convergent beam diffraction, where available, can be preferred.
This document is applicable to the acquisition of SAED patterns from crystalline specimens, indexing the
patterns and calibration of the camera constant.
2 Normative references
There are no normative references in this document.
3 Terms, definitions and abbreviated terms abbreviations
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— — ISO Online browsing platform: available at https://www.iso.org/obphttps://www.iso.org/obp
— — IEC Electropedia: available at https://www.electropedia.org/https://www.electropedia.org/
3.1 Terms and definitions
3.1.1 3.1.1
Miller notation
indexing system for crystallographic planes and directions
...