High efficient Eu3+-activated Ca(La, Gd)MgSbO6 double perovskite phosphors: Thermal stability improvement by composition modulating

A series of high efficient Eu3+-activated Ca(La, Gd)MgSbO6 phosphors were synthesized. Based on CaLaMgSbO6:Eu3+, Gd3+ was used to replace La3+ to improve the luminescence properties. Structure information was obtained by X-ray diffraction and the software Diamond. Site occupancy, coordinates and the lattice parameters were obtained by Rietveld refinement. Site occupancy of La3+/Gd3+ was rather close to the stoichiometric proportion. The photoluminescence (PL) intensity was enhanced under ultraviolet (UV) light. Schematic illustration of energy transfer and energy level were performed to show the luminescence process. UV–visible diffuse reflectance spectra were carried out to obtain the band gap. This phosphor presented great thermoluminescence (TL) stability based on the TL curves. Quenching mechanism was investigated in detail by means of the band gap. The luminescence properties manifest that this kind of double perovskite phosphor is a good candidate for solid-state lighting.