Elastic constants of boron nitride

Using Brillouin scattering the three independent elastic stiffness constants cij of single-crystal cubic boron nitride have been measured: c11=820, c12=190, and c44=480 GPa. The resulting bulk modulus, 400 GPa, is in reasonable agreement with two independent determinations obtained from x-ray measurements in a diamond anvil cell. Using the bulk modulus it is found that the x-ray results are best fitted with a value of dB/dP=3.0.