Anharmonic contribution to the Debye-Waller factor for copper, silver, and lead.

Using high intensity ({similar_to}70 Ci) {sup 183}Ta Moessbauer sources, we have measured the elastic scattering fraction values, {ital scrF}, and the relative integrated scattering intensities for the (200), (400), (600), and (220) Bragg planes of copper and silver single crystals; and for the (200), (400), and (600) reflections of a lead single crystal. The experiments were done as a function of temperature from 82 K to a high temperature of 1086, 1211, and 507 K for Cu, Ag, and Pb, respectively. The {ital scrF} values were found by Moessbauer line-shape studies, and were used to correct the measured integrated intensities for thermal-diffuse scattering, so that accurate Debye-Waller factors (DWF`s) could be evaluated. The measured DWF`s for Cu, Ag, and Pb each have a significant anharmonic contribution at about 50% of the melting temperature ({ital T}{sub {ital m}}). Contrary to what Martin and O`Connor have reported for copper, we observed no {ital Q}{sup 4} contribution to the DWF within our experimental errors, which we estimate to be smaller than those reported by Martin and O`Connor.