The effect of doped aluminium on thermal stability of basic structures was studied experimentally in the range from 2000°C to 2400°C. The results were summarized as follows;
(1) The 4H type SiC was stabilized by aluminium, and it could be changed 4H to 6H and 6H to 4H by exclusion and inclusion of the aluminium respectively.
(2) The distortion of the lattice was caused by the aluminium and the stability of 4H structure in this temperature range was attributed to this distortion.
(3) The 15R type seemed to be unstable in these conditions.