Synthesis and up-conversion emission properties of Er-Yb co-doped double perovskite oxides

Up-conversion phosphors emit light with shorter wavelength than that of excitation light. This phenomenon is caused by multi-photon excitation and energy transfer in f orbital of rare earth elements. In this study, La2ZnTiO6 and La2MgTiO6 doped with different amounts of Er and Yb was synthesized by the complex gelation method and the up-conversion (UPC) emission was investigated. In addition, we investigated the difference in optimum amount of Er and Yb for UPC emission due to host crystals. Main crystal phases of the synthesized samples were identified as La2ZnTiO6 and La2MgTiO6 respectively by X-ray diffraction. Up-conversion emissions were measured using a spectrometer with a multi-channel photo detector and a diode laser emitting excitation light at 980nm. The optimum amount of Er and Yb in (La, Er, Yb)2ZnTiO6 for the up-conversion emission were 1mol% and 5mol%, respectively. On the other hand, the optimum amount of Er and Yb in (La, Er, Yb)2MgTiO6 were 2mol% and 2mol%, respectively. The optimized sample showed strong green and red emissions. As the result, it was shown that the double perovskite type oxide doped with Er and Yb showed UPC luminescence, and the optimum doping amount of Er and Yb depended on the host crystal.