Self-diffusion and radiation damage in α-phosphorus single crystals

Abstract

Abstract The temperature dependence and pressure dependence of self-diffusion in α-white phosphorus single crystals have been redetermined using radiotracer and plastic deformation techniques. The use of 32P-labelled tracer resulted in radiation damage to the solid by the emitted electrons (E β max= 1·71 MeV). This led to the evaluation of radiation-enhanced self-diffusion coefficients which show a similar anomalous temperature dependence to that previously reported for self-diffusion in this solid. Repetition of the experiment with 33P-labelled tracer (E β max = 0·24 MeV) yielded normal behaviour which could be described by an equation D = 3·6 × 105 exp(−114·4 ± 2·0 kJ mol−1/RT)m2sec−1. The activation energy was confirmed by plastic deformation experiments. Self-diffusion probably occurs by a vacancy migration mechanism. Studies of the pressure dependence of the self-diffusion process yield activation volumes which indicate that there may be a significant contribution to the process from di-vacancy migra...