Dielectric Properties of Cu Doped (Ba0.6Sr0.4)TiO3 High Frequency Materials

We report on the microstructural and dielectric properties of Cu-doped Ba0.6Sr0.4TiO3 ceramics prepared by sol-gel method. The samples were then sintered at a constant temperature of 1400°C. The structures of the bulks were analyzed by X-ray diffraction and scanning electron microscopy. The dielectric constant and dielectric loss at high frequencies were measured by using an Agilent 4294A precision impedance analyzer. The Cu concentration of BSTCu bulks has a strong influence on the material properties. The relative density, grain size, and dielectric constant of BSTCu bulks all increase with increasing Cu content from 0 to 5.0 mol% and then decrease with increasing Cu content up to 10.0 mol%. The system doped with 5.0 mol% Cu exhibits the highest dielectric constant of 1500 and the lowest dielectric loss of 0.026 at 100 kHz. The system doped with 10.0% Cu has the lowest thermal expansion coefficient of 5.35 ppm/°C.