Surface Brillouin scattering studies on vanadium carbide

Vanadium carbides in a range of carbon to metal ratio were investigated by surface Brillouin scattering (SBS) on the (100) and (110) surfaces. The surface acoustic wave (SAW) velocity varies with the crystal surface and direction and displays an approximately linear increase with the carbon to metal ratio. The tensor elastic constants of the samples were extracted and, while they vary significantly from the different carbon to metal ratio, the value of anisotropy ratio remains close to 0.8 for all samples. The directional dependence of the Young's modulus and shear modulus are obtained from the tensor elastic constants. In the directions chosen, both Young's modulus and the shear modulus reduce with decreasing carbon to metal ratio, with this behaviour being directionally dependent.