New compositions of double perovskite niobates with enhanced red luminescence

Red light (600–800 nm) plays an important role in the photosynthesis process of plants, therefore the development of red-light emitting phosphors for plant growth LED devices is of real interest from scientific and technological point of view. In this study, different compositions of niobate perovskites with the general formula LixMg2Nb0.992−yVyMn0.008O6 (x = 1–5, y = 0–0.25) were prepared by solid-state reaction. The influence of the lattice composition over the luminescent properties of phosphors was studied following two research directions. The first direction implies changes in the charge balance of the perovskite by varying the Li+ amount in the host lattice, while the second strategy produces lattice deformation through incorporation of various amounts of V5+at Nb5+ sites. The crystal structure, chemical composition, optical band gap, oxidation state of doping ions and luminescence properties of the samples are studied in detail. Under 483 nm excitation the photoluminescence spectra exhibit intense red emissions ascribed to the 2E→4A2 transition in Mn4+. It has been found that the addition of V5+ in Li4Mg2Nb0.992Mn0.008O6, intensifies the red emission even more with percentages up to 32 %.