Dielectric and microwave properties of ZrO2 doped CaO-SiO2-B2O3 ceramic matrix composites

The behavior of dielectric and microwave properties against sintering temperature has been carried out on CaO-SiO₂-B₂O₃ ceramic matrix composites with ZrO₂ addition. The results indicated that ZrO₂ addition was advantageous to improve the dielectric and microwave properties. X-ray diffraction (XRD) patterns show that the major crystalline β-CaSiO₃ and a little SiO₂ phase existed at the temperature ranging from 950 °C to 1050 °C. At 0.5 wt% ZrO₂, CaO-SiO₂-B₂O₃ ceramic matrix composites sintered at 1000 °C possess good dielectric properties: ?_r = 5.85, tan δ = 1.59 × 10⁻⁴ (1 MHz) and excellent microwave properties: ?_r = 5.52, Q · f = 28,487 GHz (11.11 GHz). The permittivity of Zr-doped CaO-SiO₂-B₂O₃ ceramic matrix composites exhibited very little temperature dependence, which was less than ±2% over the temperature range of −50 to 150 °C. Moreover, the ZrO₂-doped CaO-SiO₂-B₂O₃ ceramic matrix composites have low permittivity below 5.5 over a wide frequency range from 20 Hz to 1 MHz.