Journal of the American Ceramic Society, Vol.84, No.12, 3013-3016, 2001
Phase relationship between 3C-and 6H-silicon carbide at high pressure and high temperature
The phase relationship between 3C- and 6H-SiC is investigated in the pressure range 2.5-6.5 GPa and the temperature range 400 degrees -2500 degreesC, by analyzing recovered samples, using X-ray diffractometry and Raman-scattering techniques. The phased transition from 3C- to 6H-SiC occurs at 2200 degreesC and 2.5 GPa. In the pressure range >4.5 GPa, 6H-SiC transforms to 3C-SiC at 2500 degreesC, via an intermediate state, as indicated by broadening peaks in the X-ray diffraction profile. Thermodynamically, 3C-SiC appears to be the low-temperature stable form, and the temperature of transition to 611-SiC, which is stable at high temperature, appears to increase with pressure.