Size-controlling of Starting Powders for Zn₂（Ti_xSn_1－x）O₄: Eu Phosphor Synthesized by Solid State Reaction

Abstract

We attempted to use Zn₂（Ti_xSn_1－x）O₄ solid solutions as a host material for a new phosphor. Eu^3＋ ion was used as an activator for the phosphor. In general, larger Eu^3＋ ion was not easy to diffuse into the smaller crystal structure of the host material by solid state reaction. At the present stage, the sizes of the starting powders are controlled by ball-milling. When the powder sizes were under 0.080μm, red emission was observed around 620 nm by the 4f-4f transition of Eu^3＋ ion in the （Zn_1.96Eu_0.04）（Ti_0.3Sn_0.7）O_4±δ phosphor. However, a yellow emission was observed when the particle sizes were larger than 0.1μm and/or Ti content was larger than Sn content. The yellow emission was caused by defects in the crystal. We assumed that the difference in the emission color was caused by the difference in the occupation-site for Eu^3＋ ion in the crystal structure.