本文件规定了小角度X射线散射（SAXS）在测定比表面积中的应用。可以获得1 m2g-1至2000 m2g-1的质量比表面积和0.01 m2cm-3至1000 m2cm-3的体积比表面积。 所述方法适用于稀释和浓缩系统。 注:在ISO 17867:2020中，通过SAXS测定粒径仅限于稀释系统。 使用SAXS确定表面仅适用于两相系统。具有两个以上相位的系统中的表面测定超出了本文件的范围。 术语“表面”是指不同密度域（更准确地说:电子密度）之间的任何界面，不限于粒子的外表面。 由于可以探测具有不同电子密度的区域之间的任何界面，而不仅仅是空气或真空，因此该方法可以应用于任何非均质系统。 SAXS不仅测量开孔的比表面积，还测量不可接近、闭合孔或包裹体的比表面积。 注:这与ISO 9277:2010中描述的气体吸附方法相反。 除了多孔系统外，只要存在电子密度对比，内部界面也可以对任何非均质致密固体系统的测量比表面积作出贡献，例如晶相和非晶相之间的比表面积。虽然包含微孔（孔宽度<2 nm）的材料也可以用SAXS根据其比表面积进行分析，但本文并不涵盖这些材料。

This document specifies the application of small-angle X-ray scattering (SAXS) for the determination of specific surface area. Both the mass specific surface area in the order of 1 m2g-1 to 2 000 m2g-1 and the volume specific surface areas in the range from 0,01 m2cm-3 to 1 000 m2cm-3 can be obtained. The method described is applicable to dilute and concentrated systems. NOTE In ISO 17867:2020, the determination of the particle size by SAXS is limited to dilute systems. The determination of surfaces with SAXS is straightforward for two-phase systems only. Surface determination in systems with more than two phases is beyond the scope of this document. The term 'surface' refers to any interface between domains of different density (more precisely: electron density) and is not restricted to the external surface of particles. As any interfaces between areas with different electron density, not only to air or vacuum, can be probed, the method can be applied to any heterogeneous system. SAXS measures not only the specific surface area of open pores but also of inaccessible, closed pores or inclusions. NOTE This is in contrast to gas sorption methods which are described in ISO 9277:2010. In addition to porous systems, there can be contributions of internal interfaces to the measured specific surface area of any heterogeneous compact solid system, such as between crystalline and amorphous phases, provided there is an electron density contrast. Although materials comprising micropores (pore width < 2 nm) can also be analysed with respect to their specific surface area with SAXS, this document does not cover these materials.