X-ray powder diffractometry

In ALMA Laboratory, X-ray powder diffraction (XRPD) has a long tradition. ALMA was involved in the testing, and as one of the first laboratories in the field of cultural heritage research started to use laboratory X-ray powder micro-diffraction (micro-XRPD), which enables analysis of heterogeneous fragments of paints or their cross-sections without any pre-treatment. Despite its lower spatial resolution or longer measuring times, it proved to be – in many cases – more efficient and reliable method for identification of crystalline phases in paint layers than the widely-used Raman micro-spectroscopy.

The field of application of micro-XRPD is very wide – it has an irreplaceable role in the provenance analysis of mineral pigments, especially clay pigments, in the distinction of various structural types of pigments or in the analysis of degradation products, crystalline metal soaps or salt corrosion. It is the basic tool of mineralogical analysis in ALMA. Recently, the method has also been adapted for measurement of small paintings (miniatures), which represents a completely new way of its application.