Red-emitting double perovskite phosphors Sr1−xCaxLaMgSbO6:Eu3+: Luminescence improvement based on composition modulation

Crystal structures of Sr1-xCaxLaMgSbO6:Eu3+ phosphors were studied in detail. Both the SrLaMgSbO6 and the CaLaMgSbO6 have a monoclinic (P21/n) structure. With increasing the Ca2+ concentration, the peaks gradually divided and the phase changed from SrLaMgSbO6 to CaLaMgSbO6. The symmetry of La3+ in SrLaMgSbO6 is lower than that in CaLaMgSbO6. Eu3+ ions, as the structural probes, were selected to study the structure. Lifetimes and intensity ratio were used to study the symmetry in the structure. Thermal quenching of the phosphors was discussed from 323 K to 473 K. The emission intensities of 5D1→7FJ and 5D0→7FJ damped in different ratios while increasing temperature. The configurational coordinate diagram was used to explain this interesting phenomenon.