An X-ray analysis of anomalous dispersion effects, anharmonicity and thermal vibrations in gallium phosphide

Abstract

Thermal vibrations of gallium and phosphorus atoms in gallium phosphide have been determined from the integrated intensities of Bragg reflections measured at ambient temperature. The thermal parameter values, obtained from the least-squares refinement, are B Ga = 0.66 ± 0.06 Å 2 and B p = 0.94 ± 0.10 Å 2 . Anharmonic thermal vibration effect is found to be small. The inclusion of dispersion corrections and anharmonicity in the structure factor expressions for GaP is found to give rise to the breakdown of Friedel's law for all even index reflections also. The observed Bijvoet ratios for several reflections are in general agreement with the calculated values.