Pressure-Induced Anomalous Seebeck Coefficient in High-Entropy Nitrides.

Entropy-stabilized disorder in high-entropy ceramics provides a versatile pathway for engineering novel functional properties, yet their electronic behavior under simultaneous high-pressure and high-temperature conditions remains largely unexplored. Here, we report a combined experimental and theoretical investigation of the rock-salt (VNbTaTi)N high-entropy nitrides (HENs), conducting in situ electrical transport measurements under pressures up to 4.0 GPa and temperatures up to 1323 K. Our results reveal that the temperature dependence of the Seebeck coefficient is substantially suppressed under high pressure relative to ambient conditions, which is unambiguously ascribed to a pressure-induced elevation of charge carrier concentration validated by our theoretical simulations. At ambient pressure, these (VNbTaTi)N HENs exhibit a superior Seebeck coefficient of 18.1(2) μV/K and a peak power factor of 63.8(8) μW/(m·K2), surpassing numerous conventional nitride counterparts like VN. Concurrently, it demonstrates robust mechanical properties with a hardness of 19.9(5) GPa and a Young's modulus of 403(20) GPa. Our findings highlight the pressure response of electronic transport in HENs and establish them as a promising class of materials that intrinsically combine efficient thermoelectric conversion with exceptional mechanical resilience for demanding applications.