Luminescent Characteristics of Ba(1--x)Al2Si2O8:xTb3+ Green Phosphors

Effect of kaolinite edge surfaces on formation of Tb3+-doped phosphor by solid-state reaction

This study assessed the effect of kaolinite edge surfaces on solid-state reactions. Specifically, Tb³⁺-doped metastable CaAl₂Si₂O₈ showing green phosphorescence was prepared via a solid-state reaction between expanded kaolinite, a methoxy-modified kaolinite, having Tb³⁺ ions adsorbed on its edge surfaces and CaCO₃. This material cannot be obtained by the conventional grinding of kaolinite, CaCO₃ and Tb₂O₃, indicating that the use of kaolinite edge surfaces is advantageous as a means of achieving certain solid-state reactions.

The effect of kaolinite edge surfaces on a solid-state reaction was demonstrated by the synthesis of Tb³⁺-doped metastable CaAl₂Si₂O₈, indicating the importance of Tb³⁺ adsorbed on kaolinite edge surfaces.

Synthesis and luminescence characterization of Y2 BaZnO5 :RE (RE = Eu3+ , Tb3+ , Pr3+ and Sm3+ ) phosphors

Modified synthesis and luminescence of Y₂ BaZnO₅ phosphors activated with the rare earths (RE) Eu³⁺ , Tb³⁺ , Pr³⁺ and Sm³⁺ are reported. RE₂ BaZnO₅ phosphors have attracted attention because of their interesting magnetic and optical properties; and are usually prepared using a two-step solid-state reaction. In the first step, carbonates or similar precursors are thoroughly mixed and heated at 900°C to decompose them to oxides. To eliminate the unwanted phases like BaRE₂ O₄ , the resulting powders are reheated at 1100°C for a long time. We prepared Y₂ BaZnO₅ phosphors activated with various activators by replacing the first step with combustion synthesis. The photoluminescence results are presented. The photoluminescence results for Eu³⁺ , Tb³⁺ and Pr³⁺ are in good agreement with the literature. However, photoluminescence emission from Sm³⁺ has not been documented previously. The excitation spectrum of Eu³⁺ is dominated by a charge transfer band around 261 nm, and an additional band around 238 nm is always present, irrespective of the type of activator. The presence of this band for all these different types of activators was interpreted as host absorption.