Positron Annihilation Spectroscopy for the Sintering of Boron Nitride Ceramics

Resumo

The sintering of graphite-like boron nitride α-BN powder was studied by positron annihilation spectroscopy with angular correlation of annihilation radiation within a temperature range from 900 to 1400°C. The changes observed in the annihilation characteristics were compared with the change in the specific surface area of samples. The model describing the bulk diffusion of positrons with their egress onto the surface of lamellae was developed. The coefficeint of positron diffusion in α-BN was estimated as D = 6.6 × 10^–5 cm²/s.