First-principles study of pressure-induced phase transitions and electronic structure of Be3P2 polymorphs

Structural parameters and electronic bandgaps of two polymorphs of Be3P2 were determined using the first-principles periodic linear combination of atomic orbitals method within the framework of density functional theory implemented in the CRYSTAL code. We studied the tetragonal structure and the cubic O-2-type polymorph of Be3P2 which is found to exist at high pressure. Coupling total energy calculations with the Murnaghan equation of state, equilibrium lattice constants and bulk moduli for tetragonal and cubic O-2-type Be3P2 are reported. Isothermal pressure-induced structural phase transitions from tetragonal! cubic O-2-type and cubic alpha -> cubic O-2-type are observed to occur at 25.5 GPa and 217.5 GPa, respectively, from enthalpy calculations. The electronic band structure calculations predict that both tetragonal and cubic O-2-type polymorphs of Be3P2 have direct bandgaps of 1.45 eV and 1.22 eV, suggesting utility in IR sensors and detectors. Pressure-dependent band structure calculations were performed to obtain pressure coefficient and volume deformation potential.