Sol-gel preparation of efficient red phosphor Mg2TiO4:Mn4+ and XAFS investigation on the substitution of Mn4+ for Ti4+

An efficient red phosphor based on the substitution of Mn4+ for Ti4+ in the lattice of Mg2TiO4 was prepared through a sol-gel route. The phosphor was characterized by X-ray diffraction (XRD), electron paramagnetic resonance (EPR) and UV-vis spectroscopy and the luminescent properties of the samples with varying Mn4+ concentrations were investigated. The photoluminescence of the sol-gel prepared Mg2TiO4:Mn4+ phosphor was compared with the corresponding sample prepared via solid-state reaction and the commercial CaAlSiN3:Eu2+. X-ray absorption fine structure (XAFS) investigation reveals the oxidation state and coordination environment of the Mn ion in the crystal structure of Mg2TiO4 and indicates the substitution of Mn4+ for Ti-sites. Moreover, a decrease in lattice parameter was observed with the increase of Mn4+ content in Mg2TiO4, further confirming the replacement of Ti4+ ions by smaller Mn4+ ions in the host lattice.