Investigation of physical, thermal, and dielectric properties of MgO-B₂O₃-SiO₂ glass-ceramics for 5G millimeter-wave applications

Millimeter-wave dielectric glass-ceramics are essential components of modern wireless communication systems. In this study, a series of MgO-B₂O₃-SiO₂ glass-ceramic compositions (MBS-1 to MBS-8) were synthesized via sol-gel process, and their structural, thermal, and millimeter-wave dielectric properties were systematically investigated. X-ray diffraction (XRD) revealed the presence of monoclinic and anorthic Mg₂(B₂O₅), as well as orthorhombic MgSiO₃ phases, depending on the MgO/SiO₂ ratio. This ratio strongly influenced crystalline phase formation, dielectric performance, and thermal behavior. Among the samples, MBS-5 sample, primarily composed of a monoclinic Mg₂B₂O₅ crystalline phase dispersed within an amorphous matrix, demonstrated excellent dielectric properties. These include a low dielectric constant of 3.74 and a dielectric loss of 0.0015 at 60 GHz. Additionally, it exhibited a coefficient of thermal expansion of 6.45 ppm/°C, thermal conductivity of 0.99 W/m·K, electrical resistivity of 5.01 × 1013 Ω cm, and a breakdown strength of 17.03 kV/mm, highlighting its strong potential for use in millimeter-wave electronic devices.