Tunable upconversion luminescence from the phosphors of Yb3+, Tm3+ and Ho3+ tri-doped Re2TeO6 (Re = La, Gd, and Lu)

Phosphors of Re2TeO6 (Re = La, Gd, and Lu) tri-doped with Yb3+, Tm3+ and Ho3+ ions have been synthesized by the solid state reactions. The crystal structures have been characterized by powder XRD measurement. The SEM images have shown the average particle sizes of the phosphors can be controlled within 1 micron. Upconversion luminescences were investigated under the excitation of 976 nm laser diode. The upconversion processes were explained based on the pump dependence of upconversion emission intensity. The light color was studied in the framework of 1931 CIE diagram. The three systems have shown nice tunabilities by changing the pump intensity and rare earth ions concentration. By properly adjusting the concentration of Tm3+ ions white upconversion luminescence can be realized in all the three tri-doped systems. Results indicated that these phosphors have potential applications in the upconversion based white lighting and optoelectronic devices.