Upconversion luminescence in langatate ceramics doped with Tm3+ and Yb3+

Abstract Ultraviolet (365 nm, 1 D 2 → 3 H 6 ), blue (480 nm, 1 G 4 → 3 H 6 ), red (650–660 nm, 1 G 4 → 3 F 4 + 3 F 2,3 → 3 H 6 ), and infrared (800 nm, 3 H 4 → 3 H 6 ) upconversion luminescence, were obtained for the first time in La 3 Ga 5.5 Ta 0.5 O 14 :Tm:Yb ceramic sample, synthesized by solid-state reaction, pumped at 973 nm. Yb 3+ →Tm 3+ energy transfer processes accounting for population of the emitting levels of Tm 3+ are discussed. Also, the back-transfer process Tm 3+ →Yb 3+ was observed. The decay curves of the metastable levels 1 D 2 , 1 G 4 , 3 H 4 , and 3 F 4 of Tm 3+ and 2 F 5/2 of Yb 3+ were analyzed. The cross-relaxation microparameters of Tm 3+ were found. The efficiency of the Yb 3+ →Tm 3+ transfer was estimated.