Elastic anisotropy and thermal properties of M-B-N (M = Al, Ga) systems using first-principles calculations

In this paper, the elastic properties, Debye temperatures, thermal conductivities, and sound velocities of M-B-N nitrides are explained systematically by considering the first-principles calculations based on density functional theory. The three-dimensional (3D) surface construction and planar projection of elastic anisotropy indicated that the elastic modulus is in the sequence of M3BN4 > MBN2 > MB3N4 and Al–B–N nitrides > Ga-B-N nitrides. The thermal properties were analyzed according to elastic modulus, and the obtained Debye temperatures, sound velocities and minimum thermal conductivities of these M-B-N nitride are anisotropic. AlB3N4 has the highest Debye temperature, indicating that AlB3N4 has the highest hardness and the largest minimum thermal conductivity among these nitrides.