Green emissions from green-colored Y₂ BaMO₅:Tb (M=Cu, Zn) materials as inorganic luminescent pigments

Photoluminescence and coloring properties of Tb³⁺ -doped Y ₂ BaMO₅ (M=Cu, Zn) were investigated for developing an inorganic luminescent pigment. Powder samples were synthesized by three kinds of methods, namely, a simple solid-state reaction, a stepwise solid-state reaction, and a precipitation. Y₂ BaZnO₅: Tb³⁺ obtained by the simple solid-state reaction showed green emissions under UV light irradiation. However, substitution of Cu²⁺ for Zn²⁺ to give the material a green color led to the quenching of the green emissions from Tb³⁺. The distance between Tb³⁺ and Cu2+ was assumed to play a crucial role in luminescence behavior due to the occurrence of Tb ³⁺ - Cu²⁺ energy transfer in this system. We then changed the synthesis method from the conventional solid-state reaction to the precipitation method based on solution chemistry. In this latter method, green-colored, green-luminescent phosphors could be obtained successfully because the coloring Cu²⁺ ions and the emitting Tb³⁺ ions were separated in the particle.