X-RAY DIFFRACTION STUDIES OF THERMAL MOTIONS IN CRYSTALS.
Final rept. 1 Jun 58-31 May 66
GEORGIA INST OF TECH ATLANTA ENGINEERING EXPERIMENT STATION
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Primarily through abstracts of reports and published papers, this final report recounts project work done from 1958 through 1966 on x-ray studies of thermal motions in crystals. Principal use was made of the temperature dependence of x-ray Bragg-reflection intensities. Precision was emphasized. Both new experimental procedures and new analytical procedures were developed to produce and to exploit the precision inherently available. Instrumental design and use strategy, X-specimen temperature control, understanding and control of the background, and wavelength control received extended attention. Analytic techniques were developed to yield from continuous intensity-vs-temperature data, absolute Debye temperatures and separate measures of Na and Cl or Ag and Cl atomic thermal motions in crystals with NaCl structure. The resulting information was surprisingly detailed. For example, comparison with calculations based on the elastic spectrum of Al showed the experimentally observable quantities to be sensitive to a 5 scaling error in one branch of that spectrum. In an ancillary effort, the thermal coefficient of expansion of AgCl was determined over the range 120-710K and the activation energy for Frankel defects was determined. Author