| Summary: | 碩士 === 東海大學 === 化學工程學系 === 95 === In this thesis, we reported on the microstructural and dielectric properties of Cu-doped Ba0.6Sr0.4TiO3 bulks and thin films prepared by sol-gel method. The Cu concentration of BSTCu bulks and thin films has a strong influence on the material properties.
The bulks were sintered at a constant temperature of 1400 °C. 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.
The thin films were coated on Pt/Ti/SiO2/Si substrates and then annealed at a temperature of 750 °C. The grain size, root-mean-square roughness, dielectric constant and tunability of BSTCu thin films all increase with increasing Cu up to 5.0 mol % and then decrease with increasing Cu content from 5.0 to 10.0 mol %. The system doped with 5.0 mol % Cu exhibits the highest dielectric constant of 810 and tenability of 66.7 % at 1 MHz. The system doped with 2.5 mol % Cu exhibits the lowest dielectric loss of 0.0214 at 1 MHz.
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