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

Abstract

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.