Crystallization Kinetics and Mechanism of Low‐Dielectric, Low‐Temperature, Cofirable CaO‐B 2 O 3 ‐SiO 2 Glass‐Ceramics

The crystallization kinetics and mechanism of low‐dielectric, low‐temperature, cofirable CaO‐B 2 O 3 ‐SiO 2 glass‐ceramics were investigated. Crystalline phases formed during firing included calcium silicates (CaSiO 3 , Ca 3 Si 2 O 7 , Ca 2 SiO 4 ) and calcium borate (CaB 2 O 4 ), with crystalline wollastonite (CaSiO 3 ) the major phase. The crystallization kinetics of wollastonite followed an Avrami equation. The results of the present study showed an apparent activation energy of 200‐260 kJ/mol. Combined with the results of reduced growth rate (growth rate × viscosity) and thermal analysis, the rate‐controlling mechanism of crystallization appeared to be a two‐dimensional surface nucleation growth. As the amount of crystalline wollastonite increased, the dielectric constant decreased, but the thermal expansion coefficient remained relatively unchanged.