Luminescence properties of double-perovskite Sr2Ca1−2x Eu x Na x MoO6 red-emitting phosphors prepared by the citric acid-assisted sol–gel method

Double-perovskite Sr2Ca1−2x Eu x Na x MoO6 red-emitting phosphors were prepared by the citric acid-assisted sol–gel method, and their luminescence properties were investigated as a function of sintering temperature and Eu3+-doping concentration. B-site substituted Sr2Ca0.8Eu0.1Na0.1MoO6 phosphor, in which Na+ ions act as charge compensators, was selected to study the thermal behavior, phase structure, microstructure, and photoluminescence property under different sintering temperatures. The photoluminescence studies on Sr2Ca1−2x Eu x Na x MoO6 (x = 0.02, 0.05, 0.10, 0.15, 0.2) show that a dominant red emission line at around 594 nm, which is due to the Eu3+ magnetic dipole transition of 5D0–7F1, is observed under different Eu3+ excitations (396 and 412 nm). Further, Eu3+ dopant content dependent emission spectra investigations of Sr2Ca1−2x Eu x Na x MoO6 phosphors indicates that, when the Eu3+ concentrations x = 0.05, there are minimum differences between the emission intensity of 5D0–7F1 transition at 594 nm and that of 5D0–7F2 transition at 615 nm. With increasing Eu3+ concentration, the variation of the emission intensities between the two transitions keep nearly invariable and Sr2Ca0.8Eu0.1Na0.1MoO6 phosphor has the strongest red emission in this series.