High pressure structural behavior of YGa < inf > 2 < /inf > : A combined experimental and theoretical study

Abstract

High pressure structural stability studies were carried out on YGa2 (AlB2 type structure at NTP, space group P6/mmm) up to a pressure of ∼35 GPa using both laboratory based rotating anode and synchrotron X-ray sources. An isostructural transition with reduced c/a ratio, was observed at ∼6 GPa and above ∼17.5 GPa, the compound transformed to orthorhombic structure. Bulk modulus B0 for the parent and high pressure phases were estimated using Birch-Murnaghan and modified Birch-Murnaghan equation of state. Electronic structure calculations based on projector augmented wave method confirms the experimentally observed two high pressure structural transitions. The calculations also reveal that the 'Ga' networks remains as two dimensional in the high pressure isostructural phase, whereas the orthorhombic phase involves three dimensional networks of 'Ga' atoms interconnected by strong covalent bonds.