High Pressure Study of HfNi Crystallographic and Electronic Structure

The crystallographic structure and electronic properties of HfNi 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 35.3 GPa, with a total volume contraction of V/V_0 = 0.85, a bulk modulus value of B_0 = 52 ± 3 GPa and B_0 ′ = 1.29 ± 0.26. The calculated linear increase in the V_(zz) value as a function of the pressure induced volume reduction at the hafnium site was attributed mainly to the p–p contribution, while in the nickel site, a non negligible d–d contribution to V_(zz) is also observed, and attributed to the high 3d-partial DOS near the nickel nucleus. Based on the total electronic DOS at E_(Fermi) calculated for 0 K (N(E^0_(Fermi))), a value of 6.85 and 5.03 (mJ/mol/k^2) was calculated for the band contribution (γ_(band)) to the electronic specific heat coefficient (γ) at a pressure of 0 and 35.3 GPa, respectively.