Crystallization mechanism and properties of CaO-B2O3-SiO2-Nb2O5 (CBSN) glass-ceramics

Abstract

CaO-B2O3-SiO2Nb2O5 (CBSN) glass-ceramics were produced by melt water quenching and isothermal heat treatment in this paper. The FTIR results showed that with the addition of Nb2O5, the combination of B-O and Si-O would be destroyed, resulting in a decrease in the number of [BO3] and [SiO4] units. The results about DSC of glass powder showed that with the increase of Nb2O5 doping amount, the softening temperature (Tg) of glass, the initial temperature of the crystallization peak (Tc), the temperature corresponding to the endothermic peak intensity (Tp) of exothermic peaks and the activation energy values of the CaSiO3 and CaB2O4 crystal phase moved to high values, indicating that the crystallization of the CaSiO3 and CaB2O4 phase became difficult. The results of crystallization kinetics showed that the nucleation rate and crystallization rate decreased near Tc1 and Tc2, indicating that the crystal phase crystallization near Tc1 and Tc2 was inhibited. The critical cooling rate decreased with the addition of Nb2O5, indicating that the viscosity of the glass system increased. The XRD results of glass-ceramics showed that the main crystal phase of the sample changed from α-CaSiO3 to β-CaSiO3 and finally to CaNb2O6 with the addition of Nb2O5.The CBSN2 glass-ceramics sintered at 865 °C for 15 min had excellent dielectric properties: εr = 6.42 and tanδ = 1.049 × 10−3 (1 MHz). The results indicated that CBSN glass-ceramics could be a potential LTCC substrate material.