Functional Materials Research Laboratory, Tongji University, Shanghai 200092, China

Ba_0.60Sr_0.40Mg_0.15Ti_0.85O₃–xmol%Mg₂TiO₄ (x = 0―40 mol%) (BSTM-MT) composite thin films were fabri-cated by sol-gel method. The precursor solution of these composite thin films was prepared through mixing the Ba_0.60Sr_0.40Mg_0.15Ti_0.85O₃and Mg₂TiO₄ solution. The microstructures and dielectric tunability of composite thin films were investigated. The dielectric constant of composite thin films can be tailored from 155 to 55 by changing the concentration of Mg₂TiO₄. The dielectric loss of these composite thin films were still kept below 0.01 and the tunability was above 20% at a dc-applied electric field of 500 kV/cm. Suitable dielectric constant, low dielectric loss, and high tunability of this kind of composite thin films can be useful for potential microwave tunable applications.

Supported by the National Program on Key Basic Research Project from the Ministry of Science and Technology of China (Grant No. 2009CB623302) and Specialized Research Fund for the Doctoral Program of Higher Education (SRFDP20060247003) and Shanghai Committee of Science and Technology (Grant No. 07DZ22302)