Unraveling the Lattice Dynamics and Inherent Emission of NaGdMgTeO ₆ Double Perovskite Phosphor

and oxygen vacancies has been observed, which results in a decrease in the overall emission intensity. Temperature-dependent emission spectra reveal that the phosphor exhibits better thermal stability at low temperatures, but undergoes rapid thermal quenching at high temperatures, with an activation energy of 0.16 eV, obtained from the Arrhenius plot. Temperature-dependent Raman analysis indicates a decrease in the phonon lifetime from 49 ps (303 K) to 37 ps (773 K), resulting in an increase in the number of phonon decay channels, contributing to observed thermal quenching.