Pressure-Induced Phase Transition of Ruthenium Diboride

Based on the first-principles calculations, we firstly predict that RuB² undergoes a phase transition from the orthorhombic phase to the hexagonal phase with a volume collapse of 1% when the applied pressure is 15.7GPa. The values of calculated elastic moduli indicate that RuB² and RuN² are low compressibility materials. Based on the calculated electronic density of states and valence charge density distribution, the bonding nature of RuB² is examined to obtain a deeper insight into the physical origin of the mechanical properties. The metallicity and high elastic moduli of RuB² and RuN² suggest that they are potential hard conductors.