1、BSI Standards PublicationBS ISO 17867:2015Particle size analysis Small-angle X-ray scatteringBS ISO 17867:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 17867:2015. The UK participation in its preparation was entrusted to TechnicalCommittee LBI/37, Partic
2、le characterization including sieving. A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards I
3、nstitution 2015.Published by BSI Standards Limited 2015ISBN 978 0 580 83350 2 ICS 19.120 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 April 2015.Amendments
4、/corrigenda issued since publicationDate T e x t a f f e c t e d ISO 2015Particle size analysis Small-angle X-ray scatteringAnalyse granulomtrique Diffusion des rayons X aux petits anglesINTERNATIONAL STANDARDISO 17867First edition 2015-05-01Reference number ISO 17867:2015(E)BS ISO 17867:2015ISO 178
5、67:2015(E)ii ISO 2015 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2015, Published in SwitzerlandAll rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
6、or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax
7、 +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 17867:2015ISO 17867:2015(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Symbols and abbreviations . 14 Principle of the method . 25 Apparatus and procedure . 36 Preliminary procedures and instrument set-up . 57 Sample preparation .
8、58 Measurement procedure 69 Calculation of the mean particle diameter 79.1 General . 79.2 Guinier approximation . 89.3 Model fitting 810 Repeatability 911 Documentation and test report. 911.1 Test report . 911.2 Technical records . 10Annex A (informative) General principles .11Annex B (informative)
9、Working size range and resolution .20Annex C (informative) System qualification 21Bibliography .22 ISO 2015 All rights reserved iiiContents PageBS ISO 17867:2015ISO 17867:2015(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (I
10、SO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, gov
11、ernmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further mainte
12、nance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents 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).Attent
13、ion is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction
14、and/or on the ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity
15、 assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT), see the following URL: Foreword Supplementary information .The committee responsible for this document is ISO/TC 24, Particle characterization including sieving, Subcommittee SC 4
16、, Particle characterization.iv ISO 2015 All rights reservedBS ISO 17867:2015ISO 17867:2015(E)IntroductionThis International Standard deals with Small-Angle X-ray Scattering (SAXS), which is performed for particle size analysis in the 1 nm to 100 nm size range. In ideal circumstances, it can provide
17、an estimate of particle size, average size and its distribution, surface area, and sometimes particle shape in a reasonably rapid measurement time. User-friendly commercial instruments are available worldwide from a number of manufacturers for both routine and more sophisticated analyses, and state-
18、of-the-art research instruments are available at synchrotron radiation facilities.As in all particle size measurement techniques, care is required in all aspects of the use of the instrument, collection of data, and further interpretation. Therefore, there is a need for an International Standard tha
19、t allows users to obtain good inter-laboratory agreement on the accuracy and reproducibility of the technique.SAXS can be applied to any hetero-phase system, in which the two or more phases have a different electron density. In most cases, the electron density corresponds reasonably well to the mass
20、 density. The so-called particle is always the phase with the smaller volume fraction. Because SAXS is sensitive to the squared electron density difference, it does not matter whether the particles constitute the denser phase and the solvent (or matrix) is the less-dense phase or vice versa. Thus, p
21、ore size distributions can be measured with SAXS in the same way as size distributions of oil droplets in emulsions or solid particles in suspensions.Although SAXS allows the determination of particle size, size distribution, surface area, and sometimes particle shape in concentrated solutions, in p
22、owders and in bulk materials, this International Standard is limited to the description of particle sizes in dilute systems. A dilute system in the sense of SAXS means that particle interactions are absent. In case of long range interactions (Coulomb forces between the particles), special care has t
23、o be taken and a reduction of the concentration or the addition of salt might be necessary.Since all illuminated particles present in the X-ray beam are measured simultaneously, SAXS results are ensemble and time averaged across all the particle orientations which are present in the sample.The shape
24、 of the particles can be assigned to a basic geometry: spheroid, disk, or cylinder. This does not exclude more detailed information about the shape of the particle being obtained. However, the method of calculation for more detailed shape analysis is very complex to be included in an International S
25、tandard at this time. The sizes of irregularly shaped nanoparticles can be assessed by the radius of gyration (Rg) as obtained by classic Guinier analysis.The size and size distribution of particles with basic shapes (sphere, disk, cylinder, core-shell, etc.) can be determined from curve fitting for
26、 relatively narrow size distributions. The reliability of the method of calculation for broader distributions depends on prior knowledge of the distribution.This International Standard assumes isotropically oriented nanoparticles of any shape in a test procedure. No dimension of the nanoparticle sha
27、ll be larger than defined by the scattering accessible to the specific SAXS instrument. This generally limits the largest measureable particle size of the conventional technique to 100 nm, although this limit can be significantly extended in samples with a very narrow size distribution.Small-angle n
28、eutron scattering is not described in this International Standard, but can be used without restriction because the theory and application are similar.A list of suitable references for further reading is given in the Bibliography. ISO 2015 All rights reserved vBS ISO 17867:2015ISO 17867:2015(E)BS ISO
29、 17867:2015Particle size analysis Small-angle X-ray scattering1 ScopeSmall-angle X-ray scattering (SAXS) is a well-established technique that allows structural information to be obtained about inhomogeneities in materials with a characteristic length from 1 nm to 100 nm. Under certain conditions (na
30、rrow size distributions, appropriate instrumental configuration, and idealised shape) the limit of 100 nm can be significantly extended. This International Standard specifies a method for the application of SAXS to the estimation of mean particle sizes in dilute dispersions where the interaction bet
31、ween the particles is negligible. This International Standard allows two complementary data evaluation methods to be performed, model fitting and Guinier approximation. The most appropriate evaluation method shall be selected by the analyst and stated clearly in the report. SAXS is sensitive to elec
32、tron density fluctuations. Therefore, particles in solution and pores in a matrix can be studied in same way.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the editi
33、on cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 26824, Particle characterization of particulate systems VocabularyISO 9276-1, Representation of results of particle size analysis Part 1: Graphical representationISO 9276-2,
34、 Representation of results of particle size analysis Part 2: Calculation of average particle sizes/diameters and moments from particle size distributions ISO/TS 27687, Nanotechnologies Terminology and definitions for nano-objects Nanoparticle, nanofibre and nanoplate3 Symbols and abbreviationsTable
35、1 SymbolsSymbol Name UnitdvsVolume-squared-weighted mean particle diameter nmdnumNumber-weighted mean particle diameter nmIoutPrimary beam intensity with sampleIinPrimary beam intensity without sampleI(q) Scattered intensity (or scattering intensity)qMomentum transfer or q-value, magnitude of the sc
36、attering vector given byq = (4 /)sinnm1r Particle radius nmRgRadius of gyration (Guinier radius, see A.4) nmtoOptimum sample thickness mmT TransmissionINTERNATIONAL STANDARD ISO 17867:2015(E) ISO 2015 All rights reserved 1BS ISO 17867:2015ISO 17867:2015(E)Symbol Name UnitV Volume of particle nm3 Wav
37、elength of the incident X-rays in vacuum nm2 Scattering angle deg or rad Linear absorption coefficient mm1 Standard deviation of size distribution4 Principle of the methodWhen electromagnetic radiation impinges on matter, a small fraction of the radiation is scattered. As a function of the scatterin
38、g angle or momentum transfer, q-value, the scattered radiation intensity profile contains information that can be used to obtain various characteristics of the material. In particular, when X-rays impinge on a geometrically ordered group of particles or molecules, this gives rise to the well-known X
39、-ray diffraction pattern at wide scattering angles which is used to characterize the unit cell and lattice constants of the material. In the small-angle regime (typically 2 5or thatqDmaxmin/4piThis International Standard recommends for the Guinier approximation measurements in the range of the limit
40、ing scattering angles between qminand qmax. All particles or aggregates with dimensions larger ISO 2015 All rights reserved 11BS ISO 17867:2015ISO 17867:2015(E)than those specified by these two limits will either not be recorded at all (if Dqmax2pimin), because their size information is not in the s
41、ignal, or will disturb the Guinier analysis by adding non-Gaussian contributions to the signal, which cannot be fitted with Guiniers method.For point-collimation instruments, the desmearing of data is not required. Therefore, the experimental data can be directly used for data modelling or Guiniers
42、analysis. When using line-collimated instruments, special care shall be taken for the presence of instrumental broadening due to collimation effects. Notable influences on the data are beam-dimensions (beam length and beam width), detector cross-talk (point-spread functions) and wavelength distribut
43、ions. Because of practical constraints, such as limited beam time and through-put, it is not always possible to circumvent non-ideal instrumental conditions of beam dimension. It is therefore recommended to use only evaluation software, which is capable of dealing with the specific instrumental cond
44、itions. There are two ways of implementing these requirements, which includes.a) desmearing of experimental data, andb) smearing of theoretical fitting functions.Both methods are generally possible. In this International Standard, we recommend the second method due to the application of the specific
45、 model of Guiniers approximation.Small-angle neutron scattering is not included in this International Standard but can be used without restrictionsa) if the distinction between two phases is made on the basis of the scattering-length density of the atomic nuclei, rather than the electron density, an
46、db) if the usual wavelength-distribution width of about /, approximately 0,1, is included in the evaluation procedure.A.3 Calculation of the radius of gyration from Guinier plotThe radius of gyration is defined as the root-mean-square of the distances from all the electrons in the particle to its ce
47、ntre of gravity of the electron distribution.RrrdVrdVvvg22=()()(A.3)where (r) is electron density. The pair-distance distribution function (PDDF) p(r) of the particle:pr ssrdsV()=()()arrowrightnosparrowrightnosparrowrightnospcombarrowextenderarrowrightnospcombarrowextender(A.4)and ss()=()particle so
48、lventis the relative electron density inside the particle at position s . The integration is taken over the whole particle volume V. The angled brackets indicate averaging over all particle orientations relative to the primary-beam direction.Particle shapes deviating from spherical can be modelled b
49、y spherical harmonics which are amenable to fitting by a range of different algorithms. Obviously, particles of different shapes can possess identical radii of gyration and the value of Rgcannot distinguish between these. For spherical particles:Rrg=()3512/(A.5)where r is the radius of a homogeneous spherical particle.12 ISO 2015 All rights reservedBS ISO 17867:2015ISO 17867:2015(E)Thus, radii of gyration shall be multiplied by (5/3)1/2 1,29 to obtain the radii of the equivalent spheres.Similarly,
