| Summary: | 碩士 === 國立虎尾科技大學 === 電子工程系碩士班 === 102 === In this investigation, an complex perovskite structure, Ba(FeTa)0.5O3 (BFT), was chosen as the host material and doped with trivalence Pr3+ and Bi3+ ions to substitute the Ba2+ ion to form Ba1-xAx(FeTa)0.5O3 (A=Pr, Bi) ceramics prepared using the reaction sintering.
In the complex perovskite oxides Ba1-xAx(FeTa)0.5O3(A=Pr, Bi) system, when the Pr3+ ion concentration increasing, the dielectric constant was decreased owing to the Pr3+ would made particle growth difficult and produced porosity increasing. The dielectric constant measured at 100 Hz is about 2×104 ~ 4×105 at room temperature for Ba0.995Pr0.005(FeTa)0.5O3 ceramic sintered at 1300 oC for 8 h. In addition, when Bi3+ ion concentration increasing, the density was increased due to the melting point of Bi2O3 is about 817 oC which could be acted as a flux reagent and increased the relative density. The dielectric constant measured at 100 Hz is about 1.5×105~2.5×105 at 25 oC for Ba0.94Bi0.06(FeTa)0.5O3 ceramic sintered at 1300 oC for 8 h. The relative densities for all the samples are over than 95%. The dielectric relaxor behavior with a broad temperature range was obtained for the BPFT and BBFT ceramics which were contributed by orientation and space charge polarization. The Cole-Cole plot analysis results indicated that the grain boundary-layer capacitance was produced for the Ba1-xAx(FeTa)0.5O3(A=Pr, Bi) system.
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