High pressure structural behavior of YGa2: A combined experimental and theoretical study

• High pressure structural stability studies were carried out on YGa2 up to 35 GPa.
• An isostructural transition with reduced c/a ratio was observed above 6 GPa.
• Above 17.5 GPa, the compound transformed to orthorhombic structure.
• PAW based electronic structure calculations have been carried out.
• Calculations confirm the experimentally observed structural transitions.

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.

High pressure X-ray diffraction patterns of YGa2 up to ~35 GPa shows an isostructural phase transition at ~5 GPa and transition to an orthorhombic structure ~14 GPa.Figure optionsDownload as PowerPoint slide