High pressure study of β-UH3 crystallographic and electronic structure

The crystallographic and electronic structure of beta-UH3 were studied as a function of pressure by combining X-ray diffraction results with the full potential linearized augmented plane wave (LAPW) calculations. No phase transition was observed up to a pressure of 29 GPa, with a total volume contraction of V/V-0 = 0.87, and a bulk modulus value of B-0 = 33 +/- 5 GPa. The calculated value of the electric field gradient main component at the uranium 6(c) site was found to be linear dependent in the pressure induced volume reduction. This linear dependence is attributed to the increase in the positive p-p contribution to the efg as a function of volume, while the negative s-d, d-d and the lattice contributions to the efg are almost pressure independent. (C) 2003 Elsevier B.V. All rights reserved.