Anharmonic contribution to the Debye-Waller factor for silver

Using high intensity 70 Ci183Ta Mossbauer sources, which have a negligible source resonance self absorption (SRSA), we have measured the relative elastic scattering fractionF(g, T) and the relative scattering intensities for the (200), (400), and (600) planes of a 6N pure silver single crystal as a function of temperature from 81 to 1211 K. The values ofF(Q, T) denote the relative fraction of incident recoilless gamma-rays that scatter from the crystal elastically. As determined by line-shape analysis of the Mossbauer spectra, theF(Q, T) values are calculated from the ratio of the measured values of the scattered to incident beam recoilless fractions, and are used to correct for thermaldiffuse scattering. The Debye-Waller factors derived from the Bragg intensities have a significant anharmonic contribution above room temperature.