Abstract
If a polycrystalline sample exhibits preferred orientation, the relative peak intensities in the powder diffraction pattern deviate from the intrinsic relative diffraction intensities, and can cause major difficulties in attempts to determine structural information from the powder diffraction pattern. To circumvent this problem, we report a straightforward and effective test that we use routinely as a screening procedure to ensure that polycrystalline samples are free of preferred orientation before recording high quality powder diffraction data for use in structure determination calculations.