Structure and luminescent properties of Eu ³⁺ doped double perovskite Sr ₂CaMoO ₆ orange-red phosphors

Series of (Sr _1-xEu _x) ₂CaMoO ₆ orange-red phosphors were prepared by EDTA-citric acid complexing method. The crystal structure, doping site, morphology, and photoluminescent properties under different Eu ³⁺ concentrations were investigated by XRD, Raman spectra, SEM and fluorescence spectra. The results by Rietveld method indicate that the structure of Eu ³⁺ doped samples is orthorhombic double-perovskite with space group P2 ₁/n and slightly tilting octahedron of (Ca/Mo)O ₆. With increasing Eu ³⁺ concentration, their lattice volumes decrease monotonously. Raman active mode T _2g, (1) is shifted to blue side resulting from the substitution of Sr ²⁺ in interstitial site among octahedrons by Eu ³⁺ ions. Under the excitation of broad and strong charge transfer band in near-UV range and blue light, the phosphor could emit a dominant orange light and a dominant red light, respectively. The (Sr _0.98Eu _0.02) ₂CaMoO ₆ phosphor has the strongest orange-red emission and this phosphor is a potential light conversion red material for N-UV LED chip.