Improved sintering behavior and microwave dielectric properties on BaZnP2O7-based ceramics

Abstract

The effects of Ca2+ substitution for Ba2+ in BaZnP2O7 ceramics on the phase composition, sintering behavior, and microwave dielectric mechanism were systematically investigated. When x ≤ 0.02, the ceramics crystallized into a single-phase solid solution of BaZnP2O7, whereas samples with x ≥ 0.04 showed mixed phases of BaZnP2O7 and CaZnP2O7. The sintering behavior was ameliorated by Ca2+ substitution, and the sintering temperature of Ba1-xCaxZnP2O7 (0 ≤ x ≤ 0.1) was reduced from 920 to 840 °C effectively. The Raman spectra and P–V-L theory confirmed that the compressed P–O bond caused by Ca2+ substitution is beneficial to reducing the lattice anharmonic vibration and enhancing the lattice energy (U), which is conducive to the improvement of the Q × f value of the Ba1-xCaxZnP2O7 ceramic when x = 0.02. Excellent microwave dielectric properties were obtained for the Ba0.98Ca0.02ZnP2O7 ceramic after sintered at 880 °C for 4 h, i.e., εr = 8.29, Q × f = 84,116 GHz, τf = −23.84 ppm/°C.