Microwave Dielectric Properties of 0.9Al_2O_3-0.1TiO_2 Ceramics Prepared by Aqueous Gelcasting

The aqueous gelcasting was used to prepare 0.9Al_2O_3-0.1TiO_2 ceramics.The microstructures,phase compositions and microwave dielectric properties of sintered 0.9Al_2O_3-0.1TiO_2 ceramics were investigated.With the help of proper calcination temperature(1200℃) and continuous and slow cooling process as annealing treatment, the Al_2TiO_5 secondary phase was successfully eliminated.Compared with conventional dry pressing method, bigger grains,less pores and more uniform microstructures are observed in the 0.9Al_2O_3-0.1TiO_2 ceramics prepared by aqueous gelcasting.Therefore,much better microwave dielectric properties are obtained in the ceramics prepared by aqueous gelcasting withe_r=10.71,Q×f= 20421GHz,τ_f=1.3×10~(-6)/℃,whereas that of ceramics prepared by dry pressing aree_r = 10.89,Q×f= 11938GHz,τ_f=1.4×10~(-6)/℃.