Triple molybdate scheelite-type upconversion phosphor NaCaLa(MoO4)3:Er3+/Yb3+: structural and spectroscopic properties

Abstract

Triple molybdate NaCaLa(1-x-y)(MoO4)3:xEr3+,yYb3+ (x = y = 0, x = 0.05 and y = 0.45, x = 0.1 and y = 0.2, x = 0.2 and y = 0) phosphors were successfully synthesized by the microwave sol-gel method for the first time. Well-crystallized particles formed after heattreatment at 900°C for 16 h showed a fine and homogeneous morphology with particle sizes of 2-3 μm. The structures were refined by Rietveld method in space group I41/a. The optical properties were examined comparatively using photoluminescence emission and Raman spectroscopy. Under the excitation at 980 nm, the NaCaLa0.7(MoO4)3:0.1Er3+,0.2Yb3+ and NaCaLa0.5(MoO4)3:0.05Er3+,0.45Yb3+ particles exhibited a strong 525-nm emission band, a weaker 550-nm emission band in the green region, and weak 655-nm, 490-nm and 410-nm emission bands in the red, blue and violet regions. The pump power dependence and Commission Internationale de L'Eclairage chromaticity of the upconversion emission intensity were evaluated in detail.