Evaluation of mechanical and thermal properties of cubic boron nitride by AB-initio calculation

Abstract

This paper describes the mechanical and thermal properties of a cubic boron nitride (cBN) by molecular orbital and molecular dynamics simulations. The interatomic potential of cBN used for the molecular dynamics simulation was proposed by an ab-initio molecular orbital calculation for a cBN cluster. The elastic stiffness and the bulk modulus of cBN were found to be close to those of diamond by the molecular simulation. The bulk modulus of cBN in the simulation agreed with that in experiment. The equilibrium molecular dynamics simulation estimated the effect of temperature on thermal conductivity and coefficient of thermal expansion of cBN. The thermal conductivity of cBN drastically decreased with increasing temperature above 150K. The coefficient of thermal expansion of cBN was independent of temperature at 50K-900K, but that of cBN increased above 900K with increasing temperature.