Rare-earth-free Sr₂YSb_1-xO₆:xMn⁴⁺: Synthesis, structure, luminescence behavior, thermal stability, and applications

We report the rare-earth-free Sr₂YSbO₆ (SYS):Mn⁴⁺ phosphors with excellent photoluminescence performance for indoor illuminations. The phase structure, elemental composition, luminescence behavior, thermal stability, lifetime, color purity, and quantum yield (QY) were analyzed in detail. The resultant sample showed a broadband excitation wavelength in the range of 250–450 nm, and the optimal doping concentration was 0.5 mol%. Under the suitable excitation wavelength of 307 nm, the SYS:0.005Mn⁴⁺ phosphor emitted a deep-red emission with the Commission Internationale de I'Eclairage chromaticity coordinate of (0.708, 0.290) and a high color purity of 93.34%. The emission intensity was found to be about 59.45% at 423 K while the activation energy was 0.28 eV. Moreover, the lifetime and QY of the optimal sample were measured to be 641.58 µs and 38.37%, respectively. Eventually, the white lighting-emitting didoes (LEDs) exhibited a strong white light with good color-rendering index (CRI) and correlated color temperature (CCT) values. Besides that, the novel LED structure based on the SYS:0.005Mn⁴⁺-polydimethylsiloxane film could also emit a warm white region while the CRI and CCT values were measured to be about 81.39 and 3091 K.