ISO 19214:2024
(Main)Microbeam analysis — Analytical electron microscopy — Method of determination for apparent growth direction of nanocrystals by transmission electron microscopy
Microbeam analysis — Analytical electron microscopy — Method of determination for apparent growth direction of nanocrystals by transmission electron microscopy
This document gives a method for determination of the apparent growth direction of nanocrystals by transmission electron microscopy. This method is applicable to all kinds of wire-like crystalline materials synthetized by various methods. This document can also guide in determining an axis direction of the second-phase particles in steels, alloys, or other materials. The applicable diameter or width of the crystals to be tested is in the range of tens to one hundred nanometres, depending on the accelerating voltage of the transmission electron microscope (TEM) and the material itself. Position, which is curved, twisted, and folded, to determine the apparent growth direction, should not be used.
Titre manque
General Information
Relations
Standards Content (Sample)
International
Standard
ISO 19214
Second edition
Microbeam analysis — Analytical
2024-10
electron microscopy — Method
of determination for apparent
growth direction of nanocrystals by
transmission electron microscopy
Reference number
© ISO 2024
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Specimens. 2
5 Analysis procedure . 2
5.1 Setting the TEM operating condition .2
5.1.1 Preparation of the TEM .2
5.1.2 Accelerating voltage .3
5.1.3 Setting the specimen .3
5.1.4 Calibration of the rotation angle .3
5.2 Data acquisition .3
5.2.1 Select the target crystal .3
5.2.2 Obtaining diffraction patterns .3
5.2.3 Determining the interplanar spacing .4
5.2.4 Index diffraction patterns.4
5.2.5 Non-uniqueness of the indexing result .5
5.3 Determination of the crystalline direction .5
5.3.1 General approach .5
5.3.2 Convert the crystallographic index .7
5.3.3 Result of the multiplicity factor .8
5.3.4 Repetition .8
6 Uncertainty estimation . 8
7 Test report .10
Annex A (informative) Relationships of Miller notation and Miller-Bravais notation for
hexagonal crystals .11
-1
Annex B (informative) Matrix G and G for the crystal systems .12
Annex C (informative) Example test report . 14
Annex D (informative) Example for determination of long-axis direction from Au nanocrystal .15
Bibliography .20
iii
Foreword
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This document was prepared by Technical Committee ISO/TC 202, Microbeam analysis, Subcommittee SC 3,
Analytical electron microscopy.
This second edition cancels and replaces the first edition (ISO 19214:2017), which has been technically
revised.
The main changes are as follows:
— the title, introduction and scope have been revised;
— Clause 3 has been revised;
— Figures 1 and 2 have been replaced;
— Annex D has been added;
— editorial revisions have been made.
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.html.
iv
Introduction
Nanocrystals are a main component in some advanced materials, especially nanomaterials, and also
appear in traditional materials, such as needle-shaped precipitates in steels and alloys. Controlling the
microstructure of these materials during fabrication is very important for quality control considerations.
To control the microstructure and thereby improve the service properties of the relevant materials, the
apparent growth direction, or the longest axis of the nanocrystals is one of the essential parameters. This
direction of nanocrystals is generally determined by transmission electron microscopy (TEM).
v
International Standard ISO 19214:2024(en)
Microbeam analysis — Analytical electron microscopy —
Method of determination for apparent growth direction of
nanocrystals by transmission electron microscopy
1 Scope
This document gives a method for determination of the apparent growth direction of nanocrystals by
transmission electron microscopy. This method is applicable to all kinds of wire-like crystalline materials
synthetized by various methods. This document can also guide in determining an axis direction of the
second-phase particles in steels, alloys, or other materials. The applicable diameter or width of the crystals
to be tested is in the range of tens to one hundred nanometres, depending on the accelerating voltage of
the transmission electron microscope (TEM) and the material itself. Position, which is curved, twisted, and
folded, to determine the apparent growth direction, should not be used.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
the requirements of this document. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 15932, Microbeam analysis — Analytical electron microscopy — Vocabulary
ISO 25498:2018, Microbeam analysis — Analytical electron microscopy — Selected area electron diffraction
analysis using a transmission electron microscope
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 15932 and the following 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/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
nanocrystal
discrete piece of crystalline material exhibiting a dimensional anisotropy with an axial elongation in one of
the three nanocrystalline lattice direction in the nanoscale
3.2
apparent growth direction
crystalline direction which is parallel to the longest dimension of a single crystal
Note 1 to entry: Apparent growth direction does not involve mechanisms of the phase interface migration.
3.3
Miller notation
indexing system for diffraction patterns, which describes a crystal lattice by three axes coordinate
3.4
Miller-Bravais notation
indexing system for diffraction patterns of hexagonal crystal, which describes the lattice by four axes
coordinate
3.5
reciprocal vector
g
hkl
coordinate vector of hkl lattice point in the reciprocal lattice
Note 1 to entry: Reciprocal vector g is perpendicular to the plane (hkl) of crystal, its length is inversely proportional
hkl
to the interplanar spacing d .
hkl
[SOURCE: ISO 25498:2018, 3.8, modified — Note 1 to entry has been modified. ]
3.6
R vector
R
hkl
coordinate vector from the central spot 000 to the diffraction spot hkl in a diffraction pattern
[SOURCE: ISO 25498:2018, 3.9, modified — Note 1 to entry has been removed.]
3.7
reciprocal space
imaginary space where planes of atoms are represented by reciprocal points and all lengths are the inverse
of their length in real space
4 Specimens
4.1 The sample crystals shall be clean, without contamination or oxidation. They are stable under electron
beam irradiation during TEM analysis.
4.2 Powder or extracted powder specimens of the crystals may be analysed. The sample powder shall be
well dispersed by a suitable technique so that individual crystals can be observed under the TEM.
NOTE One of the techniques in common use is ultrasonic dispersion. In this method, the sample powder is
immersed in ethanol or pure water and dispersed by ultrasonication for about 0,5 h to 1 h, then dropped onto the
supporting film surface of a microgrid. Then, the microgrids are dried at room temperature. The wire-like crystals
are usually parallel to
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