High pressure study and electronic structure of the super-alloy HfIr ₃

The crystallographic structure of HfIr₃ was studied as a function of pressure using X-ray diffraction technique. No phase transition was observed up to a pressure of 27.6 GPa, with a total volume contraction of V/V0 0.92. The bulk modulus value, calculated from the X-ray experimental data and from the sound-velocity technique, are B=279±4 and 297.9±2.5 GPa, respectively. The relatively high value of the bulk modulus, combined with a high density value of ρ=20564 kg/m³, and a high hardness value of 6.05±0.26 GPa, positions this compound as a possible application for extreme environments. The electronic structure of HfIr₃, studied with the full potential linearized augmented plane calculations technique, indicates that the main cause for the unusual properties of this compound are the Iridium unfilled 5d-shell of this atom.