Neutron diffraction study of anharmonic thermal vibration in AuGa2
AbstractAnharmonic effects are observed in a room-temperature neutron diffraction study of the intermetallic fluorite compound AuGa2. The analysis is performed on the basis of a single anharmonic vibrational parameter in addition to the harmonic vibrational parameters. It yields the values Au = 3.08 (0.11) x 10-12 erg A-2, Ga = 2.91 (0.08) x 10-12 erg A-2 for the harmonic parameters and Ga = -- 2. 3 (1.2) x 10-12 erg A-3 for the cubic anharmonic parameter. The Debye temperature is determined to be OM = 169 (3) K at 294 K. Neglect of the thermal diffuse scattering correction is found to introduce an error of ~ 10% in the Debye-Waller factors obtained. Least-squares analyses using the Zachariasen and the Becker & Coppens extinction corrections are found to give equivalent results.