Crystallization kinetics of La2O3–Al2O3–B2O3 glass–ceramic composites

One glass formulation (L2 glass) with the composition of La2O3, Al2O3 and B2O3 in a molar ratio of 10:10:80 was selected to cofire with Al2O3 filler. The composites underwent a two-stage crystalline evolution in the temperature range of 800 to 975 °C. The crystallization kinetics of LaBO3 grains and the transformation to LaAl2B3O9 phase were investigated by DTA, XRD, SEM/EDS, and TEM. The results showed that the Al2O3 filler plays an important role as the heterogeneous sites of LaBO3 nuclei, and as reactant for the formation of flaky LaAl2B3O9 crystals. The apparent activation energy of LaBO3-phase formation in L2 glass was 534 kJ/mol and reduced to 466 kJ/mol by the addition of Al2O3. The detail transformation reactions, kinetics, and the crystalline orientation relationship between those phases are reported.