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: ɛr = 5.85, tan δ = 1.59 × 10−4 (1 MHz) and excellent microwave properties: ɛr = 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.

Research highlights▶ In this study, we examine the ZrO2 as the sintering aid which can improve the sintering and dielectric properties. ▶ We study the resultant dielectric and microwave properties at different sintering temperatures. ▶ The CaO–SiO2–B2O3 ceramic matrix composites were synthesized by solid-phase method using (Ca(OH)2), silicic acid (H2SiO3) and H3BO3 as source materials with 0.3, 0.5 and 1.0 wt% of ZrO2.