Review—Temperature Dependence of Luminescence Intensity and Decay Time in Mn4+-Activated Oxide Phosphors

Thermal stability of the phosphor materials is of crucial importance and scientific interest. Mn 4+ -activated “fluoride” phosphors are known to sometimes show an anomalous thermal quenching (TQ) behavior. This behavior is an increase in the integrated photoluminescence (PL) intensity I PL with increasing temperature T , called negative TQ, and is understood to be due to the electric dipole (parity) forbidden transitions of 2 E g → 4 A 2 g gained by coupling with the odd-parity lattice vibrations, ν 3 , ν 4 , and ν 6 . The same behavior can also occur in Mn 4+ -activated “oxide” phosphors. The present article discusses the temperature dependence of the integrated PL intensity I PL ( T ) for the Mn 4+ -activated oxide phosphors focusing on the negative TQ phenomenon. The effects of the 4 A 2 g → 4 T 2 g excitation transitions in conjunction with those of the normal (i.e., positive) TQ are considered for developing new analysis model of I PL vs T data. Our proposed analysis model shows a good agreement with the experimental data. Discussion is also given on the temperature dependence of decay time τ ( T ) and quantum efficiency η ( T ), in comparison with I PL ( T ), demonstrating a strong correlation among such important phosphor properties except for an occurrence of negative TQ only in I PL ( T ).