Luminescence analysis of Mn4+,Zn2+: Li2TiO3 red phosphors

The Mn4+,Zn2+:Li2TiO3red phosphors are synthesized through the high temperature solid state reaction method. The XRD, SEM, ICP, absorption spectra, excitation and emission spectra are described. The Zn2+ acts as the luminescence adjustment ion to enhance the red emission efficiency. The phosphors have the crystal structure consisting of [TiO6] and [LiO6] octahedral sites and the Zn-O-Zn bonds. Concentration dependence on Zn2+ in Mn4+,Zn2+: Li2TiO3 is presented. Results indicate the suitable concentration of Zn2+ can enhance the emission efficiency. In the region of 682-697 nm when excited by 475 nm, the external quantum efficiency are obtained to be 18%, correlative with the transition of 2Eg (2T1)→4A2g of Mn4+. The crystal field strength (Dq) and the Racah parameters (B and C) are estimated to evaluate the nephelauxetic effect of Mn4+. The white-LED performances and thermal stability are also presented.