5ZnO·2B2O3–Pb1.5Nb2O6.5 microwave dielectric ceramics with near-zero temperature coefficient of resonant frequency

Abstract

The effects of Pb1.5Nb2O6.5 addition were investigated on the densification, phase evolution, microstructure, and microwave dielectric properties of 5ZnO·2B2O3 ceramics. It was shown that a 5.5mol% addition of Pb1.5Nb2O6.5 to 5ZnO·2B2O3 ceramics successfully tailored its temperature coefficient of resonant frequency (τf) from −80 to ~0ppm/°C and lowered its sintering temperature from 955 to 890°C without degrading its microwave dielectric properties. 5ZnO·2B2O3 ceramics sintered at 890−910°C for 3h with 5.0−6.0mol% Pb1.5Nb2O6.5 additions exhibited excellent microwave dielectric properties: εr=7.8−8.3, Q×f=11,500−15,200GHz, and −9.2ppm/°C≤τf≤+6.6ppm/°C @ ~7.4GHz. The ceramics showed cofiring compatibility with Ag and were therefore novel candidates for LTCC substrates.