Vanadium Diboride (VB2) Synthesized at High Pressure: Elastic, Mechanical, Electronic, and Magnetic Properties and Thermal Stability.

Vanadium diboride (VB2) with an AlB2-type structure has been synthesized at 8 GPa and 1700 K in a D-DIA-type multianvil apparatus. The obtained bulk modulus is B0 = 262(2) GPa with fixed B' = 4.0 for VB2 via high-pressure X-ray diffraction measurements. Meanwhile, VB2 has also been demonstrated to possess a high Vickers hardness of 27.2 ± 1.5 GPa, a high thermal stability of 1410 K in air, among the highest for transition-metal borides, and an extremely low resistivity value (41 μΩ cm) at room temperature. Results from first-principles calculations regarding the mechanical and electronic properties of VB2 are largely consistent with the experimental observations and further suggest that VB2 possesses simultaneously the properties of a hard and refractory ceramic and those of an excellent electric conductor.