White light emission materials of self-assembled rare earth molybdates NaRe(MoO4)(2) micro-particles: the controllable synthesis, growth mechanism and luminescent properties

摘要

The tetragonally double alkaline rare earth molybdates NaRe(MoO4)(2) (Re = Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Er) micro-particles in aqueous solution of Re(NO3)(3) and Na2MoO4 were prepared hydrothermally by a facile and effective EDTA-assisted method, and investigated by XRD, SEM, FE-SEM, photoluminescence (PL) excitation and emission spectra. The results showed that the radii of Re ions, pH and the molar ratio of Re(NO3)(3)/Na2MoO4 in the synthesis solution play an important role in controlling sizes, morphologies and luminescent properties of the final products. And the possible formation mechanism for the bipyramid-like structure and role of EDTA were discussed in detail. The microstructure and PL property of NaYxLa1-x(MoO4)(2):10% Eu3+ was investigated, and it showed that NaY0.5La0.5(MoO4)(2) exhibited regular sphere-like morphology and emitted the stronger red emission with better color purity than other products. When Tm3+, Dy3+ and Eu3+ with appropriate concentrations were used as dopants to modify this bipyramid NaY(MoO4)(2) material, the white light emission material of NaY(MoO4)(2):1% Tm3+-11% Dy3+-0.6% Eu3+ was successfully synthesized and its CIE chromaticity coordinates is (0.33, 0.33), which is the standard white light point. These novel white-light-emitting NaY(MoO4)(2):1% Tm3+-11% Dy3+-0.6% Eu3+ with single phase would be a promising material in the WLED field.