Assessment of preferred orientation with neutron powder diffraction data

Crystallographic texture (or preferred orientation) characterization of uniaxially pressed molybdite (MoO3) and calcite (CaCO3) powders has been carried out using the BT-1 high-resolution fixed-wavelength 32-detector powder diffractometer at the NIST Center for Neutron Research. Initially, each pattern was analysed assuming a random orientation of the crystallites. Subsequently, the March model and the generalized spherical harmonic description were used independently to extract the texture description directly from a refinement with neutron diffraction data of molybdite and calcite. The results indicate that the generalized spherical harmonic description provided a better Rietveld fit than the March model for the molybdite sample that had been subjected to the highest pressure.