Compressibility study of UIr2

UIr2 was investigated using high pressure x-ray diffraction technique up to 55 GPa. The compound remains stable in its cubic structure (Space Group: Fd-3m) up to 40 GPa. Above 40 GPa x-ray diffraction pattern indicates the emergence of a yet unidentified phase. The large structural stability of cubic MgCu2 type structure, predicted empirically, is not exhibited in this compound. Zero pressure bulk modulus and its pressure derivative are found to be 284 GPa and 7.9 respectively. The high bulk modulus value obtained is indicative of itinerant nature of 5-f electrons which is also supported by Hill limit criteria. Electronic structure calculations indicate that uranium tetrahedral network is less rigid as compared to iridium tetrahedral network. Valley in density of states at Fermi level deepens with pressure vindicating observation of a more stable phase at high pressure.