X-RAY DIFFRACTION STUDIES OF THERMAL MOTIONS IN CRYSTALS.
Quarterly progress rept. no. 26, 1 Sep-31 Dec 65,
GEORGIA INST OF TECH ATLANTA ENGINEERING EXPERIMENT STATION
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Measurements were made on germanium and silicon samples to determine the temperature dependence of X-ray diffracted intensity without changing the temperature. The expected results were calculated by the method of Demarco and Weiss Acta Cryst. 1968 1965 to eliminate uncertainties in the measurements of incident intensity, the results for each crystal were normalized to the predicted value at one point. The measurements on silicon demonstrate a much larger variation from the predictions than do those of germanium. The 777 of germanium continues to show an anomaly relative to the other hhh planes but that this anomaly is not present in the silicon measurements. This method of measurement does not show a significant difference due to variations in dislocation density. Three of the silicon samples which were measured are to be submitted for fast neutron radiation damage. Sample no. 5 will be exposed to determine the damage versus integrated flux with x-ray integrated intensity measurements being made periodically during the exposure. It appears probable that the total exposure may be about 5 x 10 to the 21st power nvt. The two larger monochromator crystals will eventually be exposed to a degree dependent on the results of the no. 5 sample.
- Physical Chemistry