Temperature dependence (13–600 K) of Mn4+ lifetime in commercial Mg28Ge7.55O32F15.04 and K2SiF6 phosphors

Understanding the Efficiency of Mn4+ Phosphors: Study of the Spinel Mg2Ti1–xMnxO4

“…That work explained the temperature dependence of the PL lifetime by considering independent contributions from 4 T 2g and 2 E g states in Boltzmann equilibrium, and a nonradiative thermal activation term, which is not explicitly included in the model but seems to be taken into account in the fitting of τ –1 ( T , P ) data (see eq 2 and Figure 3 of Wu et al). However, that work and in general most works related to the temperature dependence of Mn 4+ PL lack comparison of both τ –1 ( T , P ) and I PL ( T , P ) data with the same equation to check model consistency. ,,,,,,, …”

“…Nevertheless, this important result is behind some temperature-dependent studies of the PL intensity in other oxide phosphors, where intensity and lifetime data are barely compared. Different studies on Mn 4+ PL ,− show examples where the pumping efficiency can depend on temperature through thermal activation processes yielding direct nonradiative de-excitation within 4 T 2g prior to relaxation into the emitting 2 E g state. For this purpose, correlations between spectroscopic and excited-state dynamics data are worth investigating for phosphor modeling.…”

“…However, that work and in general most works related to the temperature dependence of Mn 4+ PL lack comparison of both τ −1 (T,P) and I PL (T,P) data with the same equation to check model consistency. 29,40,46,53,54,61,62,64 It is worth noting that the temperature dependence of the PL intensity in Mg 2 TiO 4 :0.1% Mn 4+ does not match the quantum yield variations as deduced from τ(T) (eq 1), as it is shown in Figure 5b. The rapid decrease of I PL (T) with respect to what is expected on the basis of eq 1 unravels an additional nonradiative channel affecting the pumping efficiency of the 4 T 2g state but not the emitting 2 E g state.…”

Advance in Red-emitting Mn4+-activated Oxyfluoride Phosphors

“…7 Unit cell of Sr 2 ScO 3 F (a) and temperature-dependent emission spectra of Sr 2 ScO 3 F:Mn 4+ (b) [27] Sr: yellow; Sc: blue; O: red; F: gray 图 8 BaTiOF 4 :Mn 4+ 的室温激发与发射光谱(a), BaTiOF 4 :Mn 4+ 的室温和低温发光光谱(b), BaTiOF 4 的晶胞(c)和[Ti 2 OF 4 ]畸 变八面体(d) [28] Fig. 8 Excitation and emission spectra of BaTiOF 4 :Mn 4+ at room temperature (a), emission spectra of BaTiOF 4 :Mn 4+ at 77 K and 293 K (b), unit cell of BaTiOF 4 (c), and distorted octahedron coordination of [Ti 2 OF 4 ] (d) [28] Ba: yellow; Ti: blue; O: red; F: gray [29] 。 六种 Mg 2+ 格位都形成八面体配位, 但其成键情况不 同, 分别为: [29] 。Mn 4+ 取代 Ge 4+ 时 为等价取代, 而取代 Mg 2+ 时需产生间隙阴离子或阳 离子空位等进行电荷补偿。Brik 等 [29] 通过电荷交换 模型研究了 Mn 4+ 在 Mg 28 Ge 7.55 O 32 F 15.04 的倾向占据 格位: [29] , 其热猝灭温度高达 700 K, 远高于 K 2 SiF 6 :Mn 4+ 荧光粉 558 K 的热猝灭温度 [34] 。在 [29] Fig. 9 Comparison of the calculated Mn 4+ energy levels in Mg 28 Ge 7.55 O 32 F 15.04 for all possible Mn 4+ positions in Ge/Mg sites with the measured spectrum [29] 图 10 LiAl 4 O 6 F 的 晶 胞 及 Al 3+ /Li + 的 配 位 多 面 体 (a) 和 LiAl 4 O 6 F:Mn 4+ 的变温发光光谱(b) [30] Fig.…”

“…9 Comparison of the calculated Mn 4+ energy levels in Mg 28 Ge 7.55 O 32 F 15.04 for all possible Mn 4+ positions in Ge/Mg sites with the measured spectrum [29] 图 10 LiAl 4 O 6 F 的 晶 胞 及 Al 3+ /Li + 的 配 位 多 面 体 (a) 和 LiAl 4 O 6 F:Mn 4+ 的变温发光光谱(b) [30] Fig. 10 Unit cell of LiAl 4 O 6 F and coordination of Al 3+ /Li + (a) and emission spectra of LiAl 4 O 6 F:Mn 4+ at temperature of 298-523 K (b) [30] 不随晶体结构改变的情况下, 较高的 4 T 2g 能级位置 使得发生非辐射跃迁所需活化能较高 [34]…”