Upconversion emission enhancement in Er3+/Yb3+-codoped BaTiO3 nanocrystals by tridoping with Li+ ions

Green upconversion luminescence in Yb3+/Er3+ co-doped ALn(MoO4)2 (A=Li, Na and K; Ln=La, Gd and Y)

“…4 I 15/2 and 4 S 3/ 2 ? 4 I 15/2 transitions of Er 3+ , respectively [14,15,18]. The latter emission at 552 nm is stronger than that of the former peaked at 530 nm because the 4 S 3/2 ?…”

“…4 I 15/2 transitions of Er 3+ ) and very weak red emission at 660 nm ( 4 F 9/2 ? 4 I 15/2 transitions of Er 3+ [18]) are observed in the emission spectrum. As the concentrations of Yb 3+ are fixed at 10 mol%, the green emission intensity becomes stronger with the increasing of Er 3+ content and reaches a maximum at 0.5 mol% in the range of 0.3-1.0 mol%, which is shown in Fig.…”

“…6b is attributed to the smaller ionic radius of Li + (0.68 Å) than Na + (0.97 Å) and K + (1.33 Å). According to previous literatures, Li + has been found favorable for improving the PL efficiency of phosphors due to their small ion radii [9,18,35]. Li + ions can occupy the cation sites and part of them can locate at the interstitial sites.…”

“…Considering the environmental protection, the fluorides based phosphors cannot be widely used for the potential toxicity of fluorine-containing species. Consequently, oxide/complex oxides based phosphors have also been studied in parallel with fluoride based phosphors for their potential applications in lighting and display in consideration of their excellent stability and low toxicity [5,6,9,10,12,18]. Double molybdates and tungstates ALn(MO 4 ) 2 (A = alkali metal ions; Ln = trivalent rare earth ions; M = Mo, W) with scheelite (CaWO 4 ) structure are efficient luminescent hosts [19][20][21] and no concentration quenching occurred in these compounds [22,23].…”

Upconversion photoluminescence properties of Er3+-doped BaxSr1−xTiO3 powders with different phase structure

“…Obviously, the emission properties of Er 3+ ion doped ferroelectrics should also be dependent on the two factors. For instance, temperature dependence of the luminescence properties has been reported in Er 3+ doped KNbO 3 and BaTiO 3 systems [8,11]. However, it seems difficult to distinguish the contribution from phase transition and the intrinsic effect of temperature on PL properties [8].…”