Significantly enhanced mechanical strength of MgNb2O6 microwave dielectric ceramics with high Q values

Abstract

MgNb2O6 ceramics doped with different amounts of flake Al2O3 (0–5 wt%) were prepared using a solid-state reaction method. The phase evolution, microstructure, microwave dielectric properties, and mechanical behavior of flake Al2O3 doped MgNb2O6 ceramics were investigated. The results show that flake Al2O3 has good chemical stability and acts as a second phase to improve the mechanical properties of the MgNb2O6 ceramics. The synergistic effects of pinning and fine grain strengthening from flake Al2O3 effectively improved the flexural strength of MgNb2O6 ceramics. The MgNb2O6 ceramics doped with 1.0 wt% flake Al2O3 exhibited excellent microwave dielectric and mechanical properties: εr = 20.1, Qf = 109 100 GHz, τf = −69 ppm/°C, and σb = 153 MPa, after sintering at 1300 °C for 4 h.