Dual Luminescence of Eu²⁺-Activated BaHfO₃ Perovskites for Effective Pressure and Thermal Sensing

The pursuit of dual-mode pressure-temperature sensors via the luminescence intensity ratio (LIR) technique demands materials with decoupled, responsive emission bands. We demonstrate an Eu²⁺-activated BaHfO₃ perovskite utilizing two distinct Eu²⁺ emissions: 5d-4f transitions (∼470 nm) and impurity-trapped exciton (ITE) luminescence (∼590 nm), in which both pressure and temperature sensing operate through ratiometric analysis of these dual bands. As a pressure sensor, the material achieves a relative sensitivity S_r(P) of 6.5% kbar^-1 at 30 kbar via pressure-modulated intensity redistribution between the Eu²⁺ and ITE bands. As a thermal sensor, it exhibits a thermal sensitivity S_r(T) above 1% K^-1 over a wide temperature range (<70 to ∼180 K), enabled by the competitive temperature dependence of the two emission bands. Operating across 0-70 kbar and 70-200 K, this work resolves the unusual dual luminescence in BaHfO₃:Eu²⁺, revealing ITE as the origin of the 590 nm band. By exploiting the 5d-ITE dual-emission mechanism, we established a unified LIR platform for spatially resolved pressure-temperature quantification, providing new insights into utilizing anomalous luminescence for both pressure and temperature sensing.