An Al³⁺-incorporated Ca₂LuNbO₆:Mn⁴⁺ oxide phosphor with dramatic deep-red and far-red emission bands

Novel Al³⁺-incorporated Ca₂LuNbO₆:Mn⁴⁺ oxide phosphors with a double-perovskite structure were successfully prepared by a high-temperature solid state reaction. Excited with 355 nm ultraviolet light, the Ca₂LuNbO₆:Mn⁴⁺ samples mainly showed a weak deep-red emission band around 625–725 nm with a peak at 685 nm. After the incorporation of a certain amount of Al³⁺, not only the deep-red emission band was continuously enhanced, but also a new far-red emission band around 680–780 nm with a peak at 710 nm was clearly observed. A further increase of the Al³⁺ content resulted in a dramatic enhancement of both the deep-red and far-red emission bands. The luminescence quantum yield of the optimal Ca₂LuNb_0.6Al_0.4O₆ : 0.3%Mn⁴⁺ sample reached about 34%, which was much higher than that without Al³⁺ (<10%). Moreover, temperature-dependent luminescence measurement demonstrated good thermal stability, making it applicable to phosphor-converted light-emitting diodes. The dramatically enhanced red emission and a broadened spectral region matched well with the absorbance range of photosensitive pigments, showing significant potential for application in plant cultivation lighting.