ELASTIC PROPERTIES OF MATERIALS BY PULSED NEUTRON POWDER DIFFRACTION

We describe the use of pulsed neutron powder diffraction to measure the mean-square thermal displacements of atoms in polycrystalline materials at various temperatures. Data for aluminum, Pu0.95Al0.05, Ce0.90Th0.10, titanium, hafnium and CeRh3B2 are presented. A simple Debye model accounts for the observations, and a Debye temperature THETA-DW can be extracted from the data. THETA-DW is atom-specific and anisotropic, and is related to the elastic constants of the material. This technique provides a means of obtaining information on the elastic behavior of materials for which the traditional methods are not applicable.