Low-Temperature Solid-State Phase Transformations in 2H Silicon Carbide

Single crystals of 2H SiC were observed to undergo phase transformations at temperatures as low as 400°C. Some 2H crystals transformed to a structure with one-dimensional disorder along the crystal c axis. Others transformed to a faulted cubic/6H structure. The transformation is time and temperature dependent, and is greatly enhanced by dislocations. Our observations indicate that the transformation takes place by means of a slip process perpendicular to the c axis. Cubic SiC crystals were observed to undergo a solid-state transformation above 1400°C.