Optical and structural properties of Mn 4+ activated (ZnxMg1‐x)2TiO4 red phosphors

International audienceWe report on optical and structural investigations of Mn4+ activated (ZnxMg1-x)2TiO4 red phosphors by X-ray diffraction, photoluminescence (PL) and electron paramagnetic resonance methods. The phosphors of Mg2TiO4, Zn2TiO4 and solid solutions (ZnxMg1-x)2TiO4 (x=0.25, 0.50, 0.75) with manganese content of 0.1 mol. % were synthesized at temperatures in the range of 800-1200 °C via solid state reaction. Formation of solid solutions of inverse spinel structure demonstrates the features similar to both the Mg2TiO4 and Zn2TiO4, i.e. decomposition of the (Zn,Mg)2TiO4 on the (Zn,Mg)TiO3 and MgO and separation of the secondary ZnO phase, respectively. These processes depend on the composition of solid solution and sintering temperature, and for some regimes the single phase phosphor can be obtained. The largest intensity of Mn4+ red PL is found in the Mn-doped (Zn0.25Mg0.75)2TiO4 phosphor sintered at 1100°C and it is 2 times larger than those in similar Mn4+ activated Mg2TiO4 phosphor. The differences in the PL intensity of the phosphors of solid solutions are explained by different PL thermal quenching as well as by competing processes of Mn incorporation in +2 and +4 charge states in zinc-magnesium titanate crystal lattice