STRUCTURAL PHASE-TRANSITION IN URANIUM ARSENIDE AND TELLURIDE

We have studied the structural phase transition due to high pressure i n UAs and UTe for the first time bg using an interatomic potential app roach based on rigid ion model formulation. The theoretically predicte d phase transition pressure and other structural properties for these compounds agree reasonably well with the measured values. The relative volume change (V/V-01) for both compounds show that it is for UTe twi ce that for UAs and hence confirms that there may be more f-d hybridiz ation mixed valence states in UTe similar to mixed valence compounds, where there is volume reduction due to f-d hybridization. We did not o bserve any high pressure structural phase transition for other uranium compounds such as USb, US, USe etc. up to 100 GPa. The nature of the force constants at equilibrium and high pressure is discussed.