Vibrational, elastic, and structural properties of cubic silicon carbide under pressure up to 75GPa: Implication for a primary pressure scale

We present results of concomitant measurements of synchrotron x-ray diffraction (XRD), Brillouin, and Raman spectroscopy on the single crystal samples of cubic silicon carbide (3C-SiC) under quasi-hydrostatic pressures up to 65GPa, as well as x-ray diffraction and Raman spectroscopy up to 75GPa. We determined the equation of state of 3C-SiC and pressure dependencies of the zone-center phonon, elastic tensor, and mode Gruneisen parameters. Cubic SiC lattice was found to be stable up to 75GPa, but there is a tendency for destabilization above 40GPa, based on softening of a transverse sound velocity. By applying the concomitant density and elasticity measurements, we determined the pressure on the SiC sample without referring to any other pressure scale thus establishing a new primary pressure scale with a 2%-4% precision up to 65 GPa. We proposed corrections to the existing ruby and neon pressure scales, and also calibrated cubic SiC as a pressure marker for the x-ray diffraction and Raman experiments. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4795348]