Pressure effects on electronic structure and electrical conductivity of TiZrHfNb high-entropy alloy

Due to specific highly distorted crystalline structure, high-entropy alloys (HEAs) are expected to demonstrate interesting behavior under high pressures. However, this issue is not yet well studied. Here we address pressure effects on electronic structure and electrical conductivity of TiZrHfNb alloy. Among the multiplicity of single-phase HEAs explored so far, the TiZrHfNb one is an exemplar of thermally stable metallic material that crystallizes into body-centered cubic (BCC) structure and demonstrates excellent mechanical, corrosion, and friction properties compared to conventional alloys. We synthesize this material with BCC structure and analyze its electrical, superconducting, and magnetic properties. The alloy is a Curie-Weiss paramagnet and a type-II superconductor with the critical temperature of about 6.3 K. The estimated upper critical field and critical current density in the HEA are rather moderate compared to those observed in the superconductors based on Ti–Nb alloys. In the normal state, the alloy demonstrates high electrical resistance that practically independent of temperature but significantly dependent on pressure; it decreases linearly by 12.5% as the pressure increases up to 5.5 GPa. By analyzing the experimental data, we suggest that alloy resistance is mainly determined by two contributions: the residual resistance and Mott's s-d scattering. We show that a cooperative effect from changes in both the Debye temperature and electronic band structure near the Fermi level are the main factors responsible for the electrical resistance behavior of the HEA under pressure. Ab initio calculations performed at different pressures support this conclusion. The results show that TiZrHfNb alloy is a promising material for designing resistance pressure gauges.