The effects of Ca/Si ratio and B₂O₃ content on the dielectric properties of the CaO–B₂O₃–SiO₂ glass–ceramics

CaO–B₂O₃–SiO₂ (CBS) glass–ceramics were used as the main research object in this study. Based on the predecessors' work, we optimized the ternary components of glass–ceramics to observe its effects on the structure, sintering performance and dielectric properties of glass–ceramics. When the content of B₂O₃ was 15.5 mol%, the Ca/Si ratio was 0.61–0.62, the glass–ceramics were transparent after water quenching, and it could achieve sintering densification under 850 °C. When the Ca/Si ratio was < 0.61 and > 0.62, the state of glass–ceramics was changed from transparent to milk-whited. As for sintering, when the sintering temperature was above 900 °C, they could achieve sintering densification. On the basis of it, we fixed the Ca/Si ratio of 0.61, and adjusted the content of B₂O₃. We found that with the increasing of the B₂O₃ content, the transparency of glass–ceramics was worse and worse, and when the samples obtained the highest density, the sintering temperature were elevated from 820 to 920 °C. According to the XRD analysis, with the B₂O₃ content added, the CaB₂O₄ crystal phases in the glass–ceramics was increased, so the permittivity of the glass–ceramics was increased. When the Ca/Si ratio was 0.61 and the B₂O₃ content was 15.5 mol%, the sintered density of CBS glass–ceramics was 2.42 g/cm³ at 850 °C, the permittivity and dielectric loss was ε_r = 5.88, tanδ = 2.8 × 10⁻³ at 10 kHz.