The Effect of Anharmonic Vibration on the Debye-Waller Factor and the Diffuse Scattering of X-Rays

Abstract

Contributions of anharmonic vibration to the Debye-Waller factor and the intensity of X-ray diffuse scattering were calculated for polyatomic crystal by the quantum statistics. Applying the anharmonic parameters which were obtained in the theory of specific heat, the contribution to the temperature factor and the intensity of diffuse scattering were estimated numerically for ionic crystals. From the comparison between the results of calculation and experiments, it was made clear that most parts of anharmonic effect arise from the thermal expansion, although cubic And quartic anharmonic contributions are noticeable for KCl at high temperatures. The effect of anharmonicity was investigated at absolute zero degree in ionic crystals.