Review—Temperature Dependence of Luminescence Intensity and Decay Time in Cr³⁺-Activated Oxide and Fluoride Phosphors

Abstract

Studying temperature dependence of light emission intensities in luminescent materials is not only of scientific interest but also technological importance. It is well known that Mn4+-activated “fluoride” phosphors 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 2g gained by coupling with the odd-parity lattice vibrations, ν 3, ν 4, and ν 6. The present article discusses the temperature dependence of the integrated PL intensity for the Cr3+-activated “oxide” and “fluoride” phosphors with an emphasis on negative TQ phenomenon. The effects of the 4 A 2g →4 T 2g excitation transitions in conjunction with those of the normal (positive) TQ are considered for developing a new analysis model of I PL(T) data. Our new analysis model shows a good agreement with the experimental I PL(T) data. Discussion is also given on the temperature dependence of luminescence decay time τ(T), demonstrating a strong correlation between I PL(T) and τ(T) except for negative TQ occurring only in I PL(T).

Chemical Tuning, Pressure, and Temperature Behavior of Mn4+ Photoluminescence in Ga2O3–Al2O3 Alloys

“…One of these energies can be interpreted as the energy distance from the minimum of the potential energy of the emitting 2 E state to the level where it overlaps with the potential energy of the 4 A 2 ground state in the configurational coordinates. The other one can be ascribed to the energy distance from 2 E to some defect states in the forbidden band gap of the host material, in line with that suggested in ref ( 37 ). A decrease of the last energy distance with an increase of the Ga content looks natural because the overall band gap of the host is strongly reduced from 8.8 eV for α-Al 2 O 3 to about 4.8 eV for β-Ga 2 O 3 .…”

“…It should be mentioned that some of the compositions show a negative thermal quenching at low temperature (Figure ). However, the low number of experimental points and their large spread in this low-temperature range do not allow us an accurate analysis in this temperature range using the approach proposed by Adachi . Therefore, thermal quenching starting only from the highest intensity (or starting from a plateau region) has been analyzed and fitted by us by eq .…”

“…However, the low number of experimental points and their large spread in this low-temperature range do not allow us an accurate analysis in this temperature range using the approach proposed by Adachi. 37 Therefore, thermal quenching starting only from the highest intensity (or starting from a plateau region) has been analyzed and fitted by us by eq 2 . The results from Table 4 and Figure 12 show that the quenching temperature ( T 1/2 ) experiences gradual shifts toward lower temperatures as the Ga content increases.…”

Probing Local Structural Changes by Sharp Luminescent Infrared Nanophosphor for Application in Light-Emitting Diodes

“…where t(T) is decay time of luminescence at temperature T; τ 0 is the low-temperature decay time (equivalent to the considering the lattice relaxation. One should notice that formula (7) does not consider the nonradiative quenching of the luminescence. However, considering that the previously discussed nonradiative process occurs with a low probability and is almost identical for all samples, the fitting of the experimental data is good at first approximation.…”

“…Infrared (IR) luminescent materials have elicited much attention due to their diverse applications, such as food analysis, plant cultivation, night vision, and biomolecular imaging. − Among all materials, Cr 3+ -doped near-infrared (NIR) phosphors are considered promising candidates because of their tunable luminescence spectra. − Most studies focus on broad-band emission IR phosphors, while the ones with sharp emissions are relatively rare. Among the sharp emission phosphors, LiGa 5 O 8 :Cr 3+ attracts our attention, which possesses both sharp and broad-band emissions and a relatively small particle size.…”