Characterization of manganese-doped willemite green phosphor gel powders

Abstract

Nanocrystalline manganese-doped zinc silicate (Zn2-xMnxSiO4; x 0-12.0 mol%) powder phosphors were prepared by the sol-gel process. Zinc chloride, tetraethylorthosilicate, and manganese chloride were employed as precursors. The influences of water concentration on the crystallization and photoluminescence of the phosphors were investigated. Single-phase wiemite (α-Zn2SiO4) started to crystallize after calcining at 600°C for powders derived from low-water-conen so, whie β-Zn2SiO4 became the dominated phase with residual ZnO trace for high-water-content sol derived powders as calcining at below 900 °C. On firing at 800°-1200°C, the resulting phosphors had the average crystallite sizes of 15∼38 nm. With various content of water and heating the powders at 800°C, the prepared phosphors exhibited yellow and green emission peaking at 556 and 524 nm, respectively. Upon heating at 1200 °C, powder phosphors exhibited prominent photoluminescence emission bands peaked at 522∼526 nm, depending on the doping content. The luminous efficiency has been investigated as a function of dopant content and heating temperature. © 2011 Ceramic Society of Japan.