Pressure- and temperature-dependent luminescence from Tm³⁺ ions doped in GdYTaO₄

Luminescent properties of Tm³⁺-doped GdYTaO₄ are studied for exploring their potential applications in temperature and pressure sensing. Two main emission peaks from ³H₄ \to ³H₆ transition of Tm³⁺ are investigated. Intensity ratio between the two peaks evolves exponentially with temperature and has a highest sensitivity of 0.014 K^-1 at 32 K. The energy difference between the two peaks increases linearly with pressure increasing at a rate of 0.38 meV/GPa. Intensity ratio between the two peaks and their emission lifetimes are also analyzed for discussing the pressure-induced variation of the sample structure. Moreover, Raman spectra recorded under high pressures indicate an isostructural phase transition of GdYTaO₄ occurring at 4.46 GPa.