Improved sintering characteristics and microwave dielectric properties of 0.02B2O3–0.98SiO2 ceramics by SiO2 nanoparticle additive

SiO2 nanoparticles (SiO2 NPs) modified 0.02B2O3–0.98SiO2 ceramics were prepared by solid state sintering. The microstructure and microwave dielectric properties were investigated. All the modified samples exhibited low-cristobalite phase with small amount of quartz. The quartz phase inhibited the cracking caused by crystallization process of low-cristobalite. The densification of 0.02B2O3–0.98SiO2 ceramics improved with SiO2 NPs addition. The introduction of 1.5 wt% SiO2 NPs brings excellent microwave dielectric properties with er = 4.4, Q × f = 42000 GHz, τf = − 5 ppm/°C for the samples sintered at 1250 °C, which can be a low-temperature sintering system as microwave substrate materials.