Laser -induced thermal effect and the role of Nd 3+in Tm 3+/Yb 3+/Nd 3+triply doped LaNbO 4 up -conversion phosphors under 808 nm excitation

In this work, intense blue up-conversion (UC) luminescence in LaNbO4: Tm3+/Yb3+/Nd3+ phosphors were obtained under the excitation of 808 nm. The laser-induced thermal effect and the role of Nd3+ in this type of phosphors were discussed. Compared with Tm3+ singly doped and Tm3+/Yb3+ doubly doped samples, thousands-fold and 30-fold overall enhancement in the blue emission intensity of Tm3+ in Tm3+/Yb3+/Nd3+ triply doped LaNbO4 were achieved with the help of Nd3+ sensitizing and the energy transfer bridging Yb3+ ion. The luminescence-enhancement effect exhibited a strong dependence on Nd3+ doping concentration, and the optimal concentration of Nd3+ was found to be 1.0 mol%. Once the doping concentration of Nd3+ exceeded this value, concentration dependent luminescence quenching occurred. Moreover, the laser-induced thermal effect on Tm3+-doped samples was investigated by using Er3+-doped sample as the thermal probe. It was found that the elevation of sample temperature induced by laser irradiation depended on both the doping concentrations of Nd3+ and the excitation power density of 808 nm laser. © 2020 Elsevier B.V.