Improved microwave dielectric properties for CaTi0.55(Al0.5Nb0.5)0.45O3 ceramics with low firing temperature by B2O3 addition

Abstract

CaTi0.55 (Al0.5Nb0.5)0.45O3 ceramics with x wt% of B2O3 additive (0 ≤ x ≤ 5) were prepared by the conventional solid-state method. And the sintering behavior, microstructure, and microwave dielectric properties of the B2O3-added CaTi0.55(Al0.5Nb0.5)0.45O3 ceramics were investigated. The results show that the additions of B2O3 significantly lower firing temperature of CaTi0.55(Al0.5Nb0.5)0.45O3 ceramics from 1540 to 1350 °C and enhance dielectric properties. The XRD results suggest that all studied compositions adopt single solid solution phase with orthorhombic structure. The SEM results also confirm no evidence of secondary phase. The permittivity (er) varies inconspicuously with the B2O3 content, and the temperature coefficient of resonant frequency (τƒ) changes toward more positive. While, the quality factor (Q × ƒ) increases obviously up to x = 3 and degrades slightly with further increasing x. Typically, an excellent dielectric properties of er = 53.9, Q × ƒ = 30308.5 GHz, τƒ = 13.2 ppm/°C are achieved for CaTi0.55(Al0.5Nb0.5)0.45O3 ceramics with 3 wt% B2O3 sintered at 1350 °C for 4 h in air, suitable for application in microwave communication fields.