PartFundamentals. Diffraction by Polycrystalline Solids. XRDOutlines. Bob He, Bruker AXS ApHarvard University. In this tutorial Abstract. PartApplications in Heterogeneous Catalysis. X-ray difraction (XRD) is an indispensable tool for characterising thin films of electroceramic materials. PartApplications in Heterogeneous Catalysis. For the beginner, however, it can be a daunting technique at Abstract. Isotropic solids. Amorphous materials can be considered as solids with liquid-like structure.