The formation of KF induced red-emitting phosphors K2TiF6·BaF(HF2):Mn4+ by cation exchange

A series of K2TiF6 •BaF(HF2):Mn4+ phosphors with narrowband red emissions have been successfully prepared on a large scale with the cation exchange method using K2MnF6 and BaTiF6 as staring materials at ambient temperature in HF-KF solution. It is interesting that KF induces the formation of luminous phase for the samples. That is that the corresponding samples will not emit light without the presence of KF. Mechanism of KF inducing formation of luminous phase is suggested. HF-controlled effects on the fluorescent properties of the samples are discussed. Decay lifetime and the photoluminescence quantum yields of the optimal sample are 4.76ms and 60.75±0.03%, respectively. The chromaticity coordinates of the optimal sample indicate that this phosphor emits deep red light (x=0.69, y=0.31), which can be used for blue light-based white LED.