Enhancement of the upconversion luminescence intensity in Er3+ doped BaTiO3 nanocrystals by codoping with Li+ ions

Upconversion photoluminescence properties of SrY2(MoO4)4:Er3+/Yb3+ phosphors synthesized by a cyclic microwave-modified sol–gel method

“…For red emission, the 4 F 9/2 level is populated by non-radiative relaxation from the 4 S 3/2 to the 4 F 9/2 level and the second ET from the 4 I 13/2 to the 4 F 9/2 level in Er 3+ . Finally, the 4 F 9/ 2 level relaxes radiatively to the ground state at the 4 I 15/2 level and releases red emissions at 655 nm [30,31]. The strong 525-nm and 550-nm emission bands in the green region, as shown in Fig.…”

“…4 I 15/2 transitions) and the red emission intensity ( 4 F 9/2 ? 4 I 15/2 transition) [10,[28][29][30][31].…”

Blue upconversion luminescence of CaMoO4:Li+/Yb3+/Tm3+ phosphors prepared by complex citrate method

“…Due to small size, Li + ion can easily enter into the host lattice, occupying not only the substitutional sites but also the interstitial sites [16,17], which can enhance upconversion luminescence by the break or distortions of crystal field around lanthanide ions. In addition, many researchers have reported greater improving upconversion luminescence via Li + co-doping in BaTiO 3 :Li + /Er 3+ [18], ZnO:Li + /Er 3+ [19] and YAG:Li + /Tm 3+ [20].…”

Preparation of PbLa2(MoO4)4:Er3+/Yb3+ particles via microwave sol–gel route and upconversion photoluminescence properties

“…3 Fig. 3 may be induced by the concentration quenching effect due to the energy transfer between the nearest Er 3 þ and Yb 3 þ ions and the interactions between the doping ions in the host matrix [40,41]. This means that the green band induced by the 4 S 3/2 -4 I 15/2 transitions is assumed to be more easily quenched than the 2 H 11/2 -4 I 15/2 transition by non-radiative relaxation in the case of the PbLa 2 MoO 4 host matrix.…”