Microwave dielectric properties of Al2O3 ceramics co-doped with MgO and Nb2O5

In this paper, the influence of MgO/Nb 2 O 5 co-doping on the microstructure and microwave dielectric properties of Al 2 O 3 ceramics has been investigated. Comparing with only MgO doped samples, the introducing of Nb 2 O 5 can further promote the densification progress and improve the microwave dielectric properties. A high Q × f value of 216,894 GHz could be obtained with 500 ppm MgO/500 ppm Nb 2 O 5 co-doped sample. Besides, MgO/Nb 2 O 5 co-doping could increase the stability of the Q × f value of the Al 2 O 3 ceramics. Charge compensation and low content of the second phase are believed to be the main reason of this high and stable Q × f value.