Structural and electronic properties of BaCrO4 at high-pressures

Particle swarm optimization technique was applied to a structural search, yielding a high-pressure phase of BaCrO4, i.e. orthorhombic P212121 phase (stable>16 GPa). The P212121 structure consists of [CrO4] tetrahedra and ionized Ba, and can be viewed as a strong distortion of the low-pressure Pnma structure. Analysis of X-ray diffraction spectrum suggested that P212121 structure might be the experimentally observed high-pressure phase at pressures above 9 GPa, which was previously identified as monoclinic P21/m structure. Moreover, the calculated electronic structure suggests that P212121 structure is a semi-conductor with a band gap of 2.63 eV.