Structural refinements of the individual grains within polycrystals and powders

A method is presented for simultaneous structural refinement of up to several hundred grains inside powders or polycrystals. The method is based on the use of hard X-rays and the indexing program GRAINDEX, where grain orientations are found by scanning in Euler space. Conventional experimental setups and refinement programs for single-crystal work can be applied. The method is validated by a study of a sintered plate of alpha-Al2O3, containing of the order of 1500 grains in the gauge volume. 57 of the largest grains were refined with respect to the Al z and O x positions as well as the isotropic atomic displacement parameters. The R1 values were 3.4% and 3.8% for the grain average and the best grain, respectively. A discussion of the potential of the method is presented, as well as the main limitation: grain size and overlap of diffraction spots.