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Ferroelectrics, which exhibit electric field dependent dielectric constant, have been of interest for possible applications on electrically controllable devices. Especially, dielectric constant of ferroelectrics could be adjusted in few microseconds to response on externally applied electric field, which made it possible ferroelectrics being used in microwave tunable devices.
In this paper, Effect of BaSrTiO2/Li2CO3 on low temperature sintering and BaSrTiO2/MgO on dielectric property of thick films has been investigated for variable capacitor on RF frequency band. The thick films were fabricated by the tape casting and then the structural and dielectric properties as a function of an addition composition of plastic-sizer ratio and sintering temperature were studied. For the thick film sintered at 1100°C, it was densified to 96 % of BaSrTiO2 theoretical density by the addition of 3 and 10 w% BaSrTiO2/Li2CO3. Dielectric constant increased and tuning range increased with the increased of BaSrTiO2/Li2CO3 content, which probably can be explained by the substitution of Ba3+, Li1+ on BaTiO3 lattice. The tunability and dielectric loss of the BaSrTiO2/Li2CO3 thick film, sintered at 1150°C, were about 43 % and 0.234 at 10~15 MHz respectively. In case of BaSrTiO2/MgO, Dielectric constant decreased and tunability increased with the added of BaSrTiO2/MgO.
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