Effect of MgO/Eu2O3 Co-doping on the Microwave Dielectric Properties of Al2O3 Ceramics

Al2O3 ceramics co-doped with MgO/Eu2O3 were prepared by wet chemical process. The effects of the content of MgO/Eu2O3 co-doping on phase composition, microstructure and microwave dielectric properties of Al2O3 ceramics were explored. The experimental results show that suitable contents of MgO/Eu2O3 can promote densification and grain growth of Al2O3. As to the dielectric properties, the influence of MgO/Eu2O3 co-doping on the dielectric constant can be ignored. However, it has a significant impact on the dielectric loss. The Qxf value increases initially and then decreases as the Eu2O3 content increases. Optimized microwave dielectric properties with epsilon(r)similar to 9.82, Qxf similar to 225,225 GHz. can be attained for the samples co-doped with 0.05wt% MgO/0.10wt% Eu2O3 sintered at 1590. for 4 h This change of Qxf value may relate to the change of sample's microstructure. Firstly, when the content of MgO/Eu2O3 increases, the grain size increases and the grain boundary decreases, which is beneficial to increase the Qxf value. Then, as the content of MgO/Eu2O3 keeps increase, the grain size decreases and the grain boundary increases, which may lead to decrease Qxf value. In addition, the presence of strain and second phase may also influence the change of Qxf value.