Assessment of the Crystallization Process of CaO-Al 2 O 3 -SiO 2 Glass Probed with Tb 3+ Luminescence.

The ratio of the intensity of Tb 3+ fluorescence at 543 nm because of an electric dipole transition ( 5 D 4 - 7 F 5 ) relative to that at 437 nm due to a magnetic dipole transition ( 5 D 3 - 7 F 4 ) was determined to be proportional to the amount of metastable CaAl 2 Si 2 O 8 crystals precipitated in CaO-Al 2 O 3 -SiO 2 glass. The present results indicate that Tb 3+ luminescence can be used as a probe to evaluate the crystallization of glass.