Investigation of the luminescent mechanism in Eu3+-doped Ln2MoO6 (Ln3+= La3+, Gd3+, Y3+) phosphors for warm WLED

Abstract

Europium-ion doped La2MoO6, Gd2MoO6, Y2MoO6 phosphors were synthesized by hydrothermal method with further calcination. The charge transfer energies of these materials were calculated by chemical bond dielectric theory of complex crystals and the results were consistent with the experiment data (ECT(La2MoO6)>ECT(Gd2MoO6)=ECT(Y2MoO6)). Notably, the larger Ω2 showed the lower symmetrical ligand field and more covalent Eu–O bonds via further Judd-Ofelt theory analysis. The optimal Eu3+ doping concentrations (x = 0.07 for La2MoO6 and Y2MoO6, y = 0.15 for Gd2MoO6) and corresponding decay times (475 us for La2MoO6:0.07Eu3+, 679 us for Gd2MoO6:0.15Eu3+ and 474 us for Y2MoO6:0.07Eu3+) were investigated. Moreover, the CIE coordinates of the as-prepared phosphors were close to the standard red light, which manifested great promise for white light-emitting devices (WLED). More importantly, our work will be anticipated to provide some guide for the choice of the materials, which is meaningful in the WLED field.