| 초록 |
(Ba,Sr,Ca) $TiO_3$ powders, which were prepared by sol-gel method using a solution of Ba-, Sr- and Ca-acetate and Ti iso-propoxide, were mixed with organic vehicle and the BSCT thick films were fabricated by the screen-printing techniques on high purity alumina substrates. The structural and dielectirc properties were investigated for various $Dy_2O_3$ doping contents. As a result of thermal analysis, the exothermic peak was observed at around 670^{ circ}C $ due to the formation of the polycrystalline perovskite phase. All BSCT thick films, sintered at $1420^{ circ}C$ for 2h, showed the typical XRD patterns of perovskite polycrystalline structure and no pyrochlore phase was observed. The average grain size of the specimens decreased with increasing amount of $Dy_2O_3$ . The average grain size and thickness of the BSCT specimens doped with 0.1 mol% $Dy_2O_3$ were approximately $1.9{ mu}m$ and $70{ mu}m$ , respectively. The relative dielectric constant decreased and dielectric loss increased with increasing amount of $Dy_2O_3$ , the values of the BSCT thick films doped with 0.1 mol% $Dy_2O_3$ were 3697 and 0.4% at 1 kHz, respectively. The leakage current densities in all BSCT thick films were less than $10^{-9}A/cm^2$ at the applied electric field range of 0-20 kV/cm. |
