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

SiO2 nanoparticles (SiO2 NPs) modified 0.02B(2)O(3)-0.98SiO(2) 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 0.02B(2)O(3)-0.98SiO(2) ceramics improved with SiO2 NPs addition. The introduction of 1.5 wt% SiO2 NPs brings excellent microwave dielectric properties with epsilon(r) = 4.4, Q x f = 42000 GHz, tau(f) = - 5 ppm/degrees C for the samples sintered at 1250 degrees C, which can be a low-temperature sintering system as microwave substrate materials.