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

Abstract

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 O²-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 O²-type Be₃P₂ are reported. Isothermal pressure-induced structural phase transitions from tetragonal → cubic O²-type and cubic α → cubic O²-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 O²-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.

Keywords:

• beryllium phosphide
• density functional theory
• electronic band structure
• equation of state
• structural phase transition

Acknowledgements

UP is grateful to the Council of Scientific and Industrial Research, New Delhi, for awarding a Senior Research Fellowship. The authors wish to thank Dr. B.K. Sharma for fruitful suggestions.