We investigate the effect of the degree of metal-oxygen octahedral facesharing on the mechanical and electronic properties of d0 BaTiO3 and d3 BaMnO3. We find that increased facesharing softens the elastic constants of both materials due to the increased volume per atom, with polar distortions also contributing to the reduction in the bulk modulus. Owing to orbital filling in the d manifold, we find the electronic band gap of BaTiO3 is relatively unaffected by changes in percent facesharing whereas the band gap of BaMnO3 increases by more than 200% as the percent facesharing increases from 0% (cubic perovskite) to 100% (hexagonal BaNiO3 perovskite). We identify that the trigonal distortions present in the face-connected polymorphs represent useful atomistic structural knobs to tune band structure in hexagonal perovskites. Our results indicate that facesharing hexagonal polymorphs provide an expanded oxides arena with additional structural flexibility beyond the usual fully corner-connected perovskites for property control.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics