Green synthesis of K2TiF6:Mn4+ using KHF2 as accessory ingredient: A novel airtight solid-state strategy

In this work, an airtight solid-state strategy was developed for the synthesis of K 2 TiF 6 :Mn 4+ phosphor without the usage of high concentration HF solution. By heating K 2 TiF 6 , K 2 MnF 6 and KHF 2 in a sealed container at 474 K for hours and then washing the as-synthesized samples several times, K 2 TiF 6 :Mn 4+ phosphor was obtained. The microstructure, luminescent properties of the phosphor were investigated systemically. The reaction mechanism were investigated and discussed in detail. KHF 2 is the key role to obtain the red phosphor, which provides additional pressure and HF gas atmosphere, works as reaction intermediate and contributes to Mn 4+ doping into K 2 TiF 6 host. By using as-prepared K 2 TiF 6 :Mn 4+ phosphor as a red componet for warm W-LEDs, the high color rendering index (Ra = 84) and low color temperature (CCT = 3621 K) device performance proved that this environmental friendly synthesis method would be an efficient way to produce red fluoride phosphor for W-LEDs.