Effect of LiCl on the crystallization behavior and luminescence of Y₃Al₅O₁₂: Tb

The single-phase cubic Y₃Al₅O₁₂: 1% Tb sol-gel-derived powders were prepared after firing at 650°C for 2 h when a LiCl flux was used. The addition of the LiCl can increase the crystalline size of the powders at low temperatures. By using the broadening effect of X-ray patterns, the estimated crystalline size of the powder with 20 wt.% LiCl addition fired at 650°C for 2 h was evaluated as 480 Å. Both emission and excitation luminescent spectra of the samples were measured. Emission spectra of the synthesized powders mainly show ⁵D₄-⁶F transition under 275 nm excitation. The excitation spectra of The Tb³⁺ ions are different between amorphous and crystalline phase because of the crystal field effect. The excitation spectra also help observing the degree of the crystallinity of the resulting YAG phase.