Lattice dynamics of NiTiO3 under high pressure: Raman evidence under two pressure-transmitting mediums

Ilmenite-type NiTiO3 has been studied by Raman spectroscopy under hydrostatic and non-hydrostatic pressure. The rhombohedral structure does not undergo phase transitions up to 35 GPa but evidence of it is found under non-hydrostatic pressure at 45 GPa. The pressure evolution of different modes will be discussed in detail. Our findings not only provide direct experimental evidence of difference in the lattice of NiTiO3 between hydrostatic and non-hydrostatic conditions, but also offer a new insight to understand the phase stability region of ilmenite minerals in the earth.

Automated summary

Ilmenite-type NiTiO3 was studied using Raman spectroscopy under both hydrostatic and non-hydrostatic pressure. The rhombohedral structure showed no phase transitions up to 35 GPa, but evidence of a transition was found at 45 GPa under non-hydrostatic pressure. The pressure evolution of different modes was discussed in detail. The findings provide experimental evidence of the difference in the lattice of NiTiO3 between hydrostatic and non-hydrostatic conditions, and offer new insights into the phase stability region of ilmenite minerals in the Earth.