Assessment of the Crystallization Process of CaO–Al2O3–SiO2 Glass Probed with Tb3+ Luminescence

The ratio of the intensity of Tb³⁺ fluorescence at 543 nm because of an electric dipole transition (⁵D₄-⁷F₅) relative to that at 437 nm due to a magnetic dipole transition (⁵D₃-⁷F₄) was determined to be proportional to the amount of metastable CaAl₂Si₂O₈ crystals precipitated in CaO-Al₂O₃-SiO₂ glass. The present results indicate that Tb³⁺ luminescence can be used as a probe to evaluate the crystallization of glass.