A Study of Lattice Vibrations Through the Temperature Dependences of X-Ray Bragg, Intensities

摘要

New experimental and analytical techniques were developed for the study of thermal vibrations through measure ments of the temperature dependences of Bragg intensities. These techniques were applied to the study of thermal vibrations in Al, Kcl, and Agcl in the 100 to 300K temperature range. These techniques involve the collection of precision intensity data at temperature intervals which are small enough to allow useful determination of the slope and curvature of the intensity versus temperature data. From these slopes it is possible to obtain meaningful values for the temperature derivatives, dB/dT, of the Debye-Waller factors for both a monatomic (copper type) structure and for each type of atom, individually in an NaCl type structure. The temperature dependences of these temperature derivatives were also experimentally observed and were particularly significant. These intensity-vs-temperature results were related in a straightforward way to the elastic frequency spectrum, and detailed comparisons were made with predictions based on the actual spectra in two cases. (Author)