Synthesis of K₂TiF₆:Mn⁴⁺ red phosphors by a simple method and their photoluminescence properties

To prepare Mn⁴⁺-activated K₂TiF₆ phosphor, a precipitation method without using hydrofluoric acid (HF) was designed. In the synthetic reaction, to prevent the decomposition of K2MnF6, which is used as a source of Mn⁴⁺ activator, NH₅F₂ solution was adopted in place of the HF solution. Single phase K₂TiF₆:Mn⁴⁺ phosphors were successfully synthesized through the designed reaction at room temperature. To acquire high luminance of the phosphor, the reaction conditions such as the type and concentration of the reactants were optimized. Also, the optimum content of Mn⁴⁺ activator was evaluator based on the emission intensity. Photoluminescence properties such as excitation and emission spectrum, decay curve, and temperature dependence of PL intensity were investigated. In order to examine the applicability of this material to a white LED, the electroluminescence property of a pc-WLED fabricated by combining the K₂TiF₆:Mn⁴⁺ phosphor with a 450 nm blue-LED chip was measured.