Surface grain orientation mapping using grazing incidence X-ray diffraction

Tomographic surface X-ray diffraction (TSXRD) is an adaptation of classic surface X-ray diffraction to allow for measurements of polycrystalline surfaces. Compared to most other surface-sensitive techniques, surface X-ray diffraction has advantages in operando studies, since it can provide crystallographic information about surface structures in high gas pressures (above atmospheric) as well as through liquids. The method has, however, so far been limited to ideal samples, such as single crystals, since the long beam footprint illuminates several grains, which, with conventional SXRD, prevents an assignment of the diffraction signal and thus the structural information, to a certain grain. Here, we present the first step in the development of TSXRD, in which the grain shapes and orientations on a polycrystalline surface can be mapped using grazing incidence X-ray diffraction. The resulting knowledge about the shape, position, and orientation of the grains at the surface will be the steppingstone for further SXRD analysis of polycrystalline surfaces, allowing us to identify which diffraction signals belong to which grain. This method is thus part of opening up SXRD as a method for operando studies of more industry-relevant samples. Our grain maps are compared to those obtained with electron back-scatter diffraction measurements of the same sample, confirming the validity of the method.