Insight into the structural, elastic and electronic properties of a new orthorhombic 6O-SiC polytype

We report the first occurrence of an orthorhombic 6O-SiC polytype as rock-forming mineral in the nickel laterite mine of Tiebaghi (New Caledonia), within the SOLSA project (EU H2020). Very small 6O-SiC single crystals enabled structure determination, confirmed by micro-Raman spectroscopy. This new orthorhombic phase was predicted using simulations as an intermediate state occuring during the wurtzite to rocksalt transformation of 6H-SiC. We calculated an indirect bandgap at room temperature of 3.56 eV, identical to the one of 6H- SiC, and similar elastic stiffness components.