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 ²E_g (²T₁)→⁴A_2g 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.