Intense near-infrared emission, upconversion processes and temperature sensing properties of Tm3+ and Yb3+ co-doped double perovskite Gd2ZnTiO6 phosphors

Preparation, luminescence properties, and application of temperature sensing and anti‐counterfeiting of La2MgTiO6:Yb3+/Ln3+/Mn4+

“…Therefore, the addition of Mn 4+ ions can greatly improve the temperature sensing performance, increasing the maximal S A value of the LMT:Yb 3+ /Ln 3+ (Er 3+ /Ho 3+ /Tm 3+ ) samples to 134.4 × 10 −4 , 113 × 10 −4 , and 5886 × 10 −4 K −1 , possibly because doping with Mn 4+ results in energy transfer from Ln 3+ , which improve the UC FIRs. What's more, increasing the values of the FIRs is an effective way to increase S A values 40–41 . In particular, the LMT:Yb 3+ /Ln 3+ and LMT:Yb 3+ /Ln 3+ /Mn 4+ phosphors have large absolute S A values compared to literature‐reported Yb 3+ /Ln 3+ doped oxides and fluorides (Table 2), 42–46 indicating their potential applications in temperature sensing.…”

“…The absolute sensitivities of all samples increase or decrease monotonically with increase in temperature, reaching the maximum at 340 or 480 K. Table 1 S A values. [40][41] In particular, the LMT:Yb 3+ /Ln 3+ and LMT:Yb 3+ /Ln 3+ /Mn 4+ phosphors have large absolute S A values compared to literature-reported Yb 3+ /Ln 3+ doped oxides and fluorides (Table 2), [42][43][44][45][46] indicating their potential applications in temperature sensing.…”

“…In the spectrum of LMT:10%Yb 3+ /1%Ho 3+ /0.15%Tm 3+ , peaks corresponding to the 5 F 5 → 5 I 8 , 5 F 4 → 5 I 8 , 5 F 3 → 5 I 8 , 5 G 6 → 5 I 8 , and 5 G 5 → 5 I 8 transitions of Ho 3+ and 3 H 6 → 3 H 4 , 3 H 6 → 3 F 2,3 , 3 H 6 → 1 G 4 , and 3 H 6 → 1 D 2 transitions of Tm 3+ were observed (Figure 2C,D). The optical band gaps ( E g ) of the LMT host and LMT:Yb 3+ /Ln 3+ phosphors were also calculated from these spectra (see insets in Figures 2A–D) using Equations (1) and (2): 34 $$\begin{equation}F({R_\infty }) = {(1 - R)^2}/2R,\end{equation}$$ $$\begin{equation}[F({R_\infty })h{v^n}] = A(hv - {E_g}).\end{equation}$$Here, R is the reflection coefficient, hv is the photon energy, n is 1/2, and A is the absorption coefficient. Using these equations, the band gaps of the LMT host and LMT:Er 3+ /Yb 3+ , LMT:Ho 3+ /Yb 3+ , and LMT:Tm 3+ /Yb 3+ samples were found to be 3.67, 3.60, 3.59, and 3.61 eV.…”

Combinations of Superior Inorganic Phosphors for Level‐Tunable Information Hiding and Encoding

“…Rich luminous colors are obtained on the basis of different Ln 3+ and their doping contents. To date, diverse cross‐relaxation (CR) and energy back transfer (EBT) processes between the same or various Ln 3+ are proved, including but not limited to (CR1) 4 S 3/2 (Er 3+ ) + 4 I 13/2 (Er 3+ ) → 4 F 9/2 (Er 3+ ) + 4 I 11/2 (Er 3+ ), [ 54 ] (EBT1) 4 S 3/2 (Er 3+ ) + 2 F 7/2 (Yb 3+ ) → 4 I 13/2 (Er 3+ ) + 2 F 5/2 (Yb 3+ ) , [ 81 ] (CR2) 4 F 7/2 (Er 3+ ) + 4 I 11/2 (Er 3+ ) → 4 F 9/2 (Er 3+ ) + 4 F 9/2 (Er 3+ ), [ 82 ] (CR3) 1 G 4 (Tm 3+ ) + 3 F 4 (Tm 3+ ) → 3 F 2,3 (Tm 3+ ) + 3 H 4 (Tm 3+ ), [ 83 ] (CR4) 5 F 4 , 5 S 2 (Ho 3+ ) + 5 I 8 (Ho 3+ ) → 5 I 4 (Ho 3+ ) + 5 I 7 (Ho 3+ ), [ 84 ] and (CR5) 1 G 4 (Tm 3+ ) + 4 I 15/2 (Er 3+ ) → 3 F 4 (Tm 3+ ) + 4 F 9/2 (Er 3+ ). [ 85 ] Due to the influence of these complex energy transfer processes, UCL outputs would be manipulated in different doping systems.…”

“…Contrastingly, the Yb 3+ is one of the most efficient sensitizers than the others, because it not only owns large absorption cross-section but also has suitable energy gap between 2 F 5/2 and 2 F 7/2 to the emitters (Er 3+ , Tm 3+ , Ho 3+ , and more). [13,83,128,129] Compared to the Yb 3+ , the Nd 3+ has more energy levels. [130] For Nd 3+ -sensitized UCL systems, the Yb 3+ is also necessary to be co-doped as a bridge between the Nd 3+ and emitters because the energy gap of Nd 3+ doesn't match well with that of the emitters.…”