Comparative study of Mn4+ 2Eg→4A2g luminescence in isostructural A2CaWO6 (A=Ca, Sr, Ba) with double perovskite structure

Red-emitting Mn4+-doped A(2)CaWO(6) (A = Ca, Sr, Ba) phosphors have been synthesized by solid-state reaction. The crystallinities and structural properties were examined by X-ray diffraction (XRD). The luminescence properties were studied by luminescence excitation, emission spectra and decay curves. All the synthesized materials emit red light peaking around 680 nm which can be assigned to the E-2(g) -> (4)A(2)g spin-forbidden transition of Mn4+ ions under the excitation of ultraviolet to blue light. The critical quenching concentrations of Mn4+ in A(2)CaWO(6) (A = Ca, Sr, Ba) system are evaluated. The temperature dependent emission spectra and decay curves (10-520 K) were introduced to evaluate the thermal stability. Surprisingly, the proposed three kinds of red phosphors show quite different thermal behavior, which can be ascribed to the different crystal structure environment of Mn4+ ions in A(2)CaWO(6) (A = Ca, Sr, Ba) system.