Microstructure and microwave dielectric properties of CaO-B₂O₃-SiO₂ glass ceramics with various B₂O₃ contents

Abstract

The effects of B₂O₃ addition on both the sintering behavior and microwave dielectric properties of CaO-B₂O₃-SiO₂ (CBS) glass ceramics were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The results show that the increasing amount of B₂O₃ causes the increase of the contents of [BO₃], [BO₄] and [SiO₄], which deduces the increase of CaB₂O₄ and α-SiO₂ and the decrease of CaSiO₃ correspondingly. No new phase is observed throughout the entire experiments. A bulk density of 2.54 g/cm³, a thermal expansion coefficient value of 11.95×10⁻⁶°C⁻¹ (20–500°C), a dielectric constant ɛ_r value of 6.42 and a dielectric loss tanδ value of 0.000 9 (measured at 9.7 GHz) are obtained for CBS glass ceramics containing 35% B₂O₃ (mass fraction) sintered at 850 °C for 15 min.

Keywords

CaO-B₂O₃-SiO₂ / B₂O₃ content / Fourier transform infrared spectroscopy / microstructure / dielectric properties