Accession Number : AD0271421

Title :   X-RAY DIFFRACTION STUDIES OF THERMAL MOTIONS IN CRYSTALS

Corporate Author : GEORGIA INST OF TECH ATLANTA ENGINEERING EXPERIMENT STATION

Personal Author(s) : YOUNG,R.A. ; NICKLOW,R.M.

Report Date : 31 MAY 1961

Pagination or Media Count : 1

Abstract : Research continued on the general study, primarily by x-ray intensity-vs-temperature (I vs T) measurements, of thermal motions in crystals and their interaction with other phenomena of interest in crystal physics. Critical re-exa ination of experimental techniques led to a better understanding of background intensities and subsequently to the solution of several persistent problems. A graphical method (curvature method) developed for comparing the temperature dependence of the normalized temperature slope of log I vs T, A(T), with the theoretical prediction, f(x), by means of log-log plots. Results indicate that the curvature method is sensitive to discrepancies between experimental observations and theory, and that the Debye-Waller theory does not adequately describe the temperature dependence of Bragg intensities for AgCl. Thermal expansion data for AgCl, NaCl, and Al in the 100 K to 300 K temperature range were obtained. The discrepancies found between theory and experiment indicate a breakdown in the simplified MieGruneisen thermal expansion theory used, or the Debye lattice vibration theory, or both, for AgCl. (Author)

Descriptors :   *ALUMINUM, *CHLORIDES, *CRYSTALS, *SILVER COMPOUNDS, *SODIUM COMPOUNDS, CRYSTAL STRUCTURE, HIGH TEMPERATURE, SINGLE CRYSTALS, TEMPERATURE, TEST EQUIPMENT, TEST METHODS, THEORY, THERMAL DIFFUSION, THERMAL EXPANSION, X RAY DIFFRACTION, X RAY FILTERS

Distribution Statement : APPROVED FOR PUBLIC RELEASE