Determination of the Size and Size Distribution of Nanoparticles by Small-angle X-ray Scattering

Nanoparticles exhibit unique material characteristics and find a wide application in many areas, such as engineering, medicine and catalysis. The precise determination of the size and size distribution of nanoparticles is crucial since it has a direct impact on a material’s properties and performance. Here we discuss the determination of the size/size distribution of liquid-suspended nanoparticles according to ISO 17867 using the small-angle X-ray scattering method.

1 Introduction

Nanoparticles (NPs) are materials with submicroscopic size which find a rapidly increasing interest due to their unique size-related material characteristics. Besides their existence in the natural world they are also and are also manufactured on a large scale, finding application in a wide variety of fields such as engineering, pharmaceutical materials, energy conversion and storage, catalysis and many more. Per definition, nanoparticles are tiny materials having a size range from 1 to 100 nm, however, also larger particles with diameters of a few hundred nanometers are described as NPs. They can be classified into different classes based on their size, shapes or properties. In principle, nanoparticles can be distinguished between organic and inorganic NPs, however, following other classifications they can be divided in carbon-based, ceramic, semiconducting/metal and polymeric nanoparticles1.

In general, nanoparticles exhibit unique physical, chemical and optical properties, which is mainly caused by their nanoscale size, their shapes and their extremely high surface area to volume ratio.

Small-angle X-ray scattering (SAXS) is a non-destructive method for analyzing nanoparticles which are present in the form of NP dispersions, as dry powders or in composite materials.

SAXS delivers representative and averaged results which are valid for a large sample volume and therefore ideally complements information obtained by high-resolution methods like electron microscopy.

In this study we show how a laboratory SAXS system is effectively used to determine the particle size of liquid-suspended silica nanoparticles. Evaluation of the experimental SAXS data is done according to standard ISO procedures (ISO 178672) for precise calculation of the particle size and its distribution.



1. King, S. et al., “Nanoparticle”. Encyclopedia Brittannica, 14 May. 2019
2. ISO 17867:2020, Particle size analysis - Small-angle X-ray scattering


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