The use of focused ion beams for the characterisation of industrial mineral microparticles

Detailed information about the external and internal structure of microparticles plays an important role in the development of new materials. Scanning electron microscopy (SEM) can be used for studying the external structure of particles and transmission electron microscopy (TEM) can be used to identify some aspects of the internal structure of particles. However, neither technique really characterises the internal structure of kaolin particles. Thermal treatment or calcination of kaolin alters the internal structure and being able to characterise these changes has always been a challenge. In recent years, the ability of a focused ion beam (FIB) to cross-section single particles thus exposing their internal structure has raised increasing interest. This paper describes how a FIB is successfully used to (i) analyse the effect of soak and flash calcining on the internal structure of kaolin and (ii) to characterise the internal structure of some other industrial mineral microparticles.