Luminescence of Eu2+ in alkali earth chlorosilicate phosphor and their color-tunable properties

Alkali earth chlorosilicate of the types Sr4−xMgxSi3O8Cl4:Eu2+ and Sr4−xCaxSi3O8Cl4:Eu2+ have been synthesized from mixtures of SrCO3, CaCO3, SrCl2 · 6H2O, SiO2, MgO, Eu2O3 and proper fluxing agent selected from NH4Cl and H3BO3, which were fired at 900–1000 °C for 2–4 h, and carbon powder was used as a reducing agent. According to the Van Uitert experimental equation, the color-tunable photoluminescence properties and crystal-lattice environment of Eu2+ in the host lattice have been studied. Depending on the ratio of Sr2+ and other alkali earth ions (Mg2+ or Ca2+) in the host, the position and intensity of different luminescence centers are influenced by Eu2+ located at different chemical environmental sites. Owing to this, it shows from blue-violet (411 nm) to greenish-yellow (565 nm) luminescence under 365nm ultraviolet radiation.