Electronic, elastic and pressure-induced phase transitions of tetragonal NaBH4 under high pressure

Abstract

In this study; the structural, electronic and mechanical properties of sodium borohydride (NaBH4) compound were studied under high hydrostatic pressure from 0 to 300 GPa using the generalized gradient approach (GGA) within the framework of density functional theory (DFT). In the study, the NaBH4 compound transformed from the tetragonal structure with the space group P42 /nmc to the triclinic structure with the space group with the effect of gradually increasing pressure. Enthalpy and total energy calculations were performed to observe the agreement of the study with the experimental results. As a result of the calculations, it was concluded that a phase transition of the NaBH4 compound occurred at approximately 22.6 GPa from the tetragonal structure to the triclinic structure. In addition, the electronic properties of the NaBH4 compound were investigated and 6.22 and 4.95 eV band gaps were obtained for the P42 /nmc and phases, respectively.