Synthesis and Dielectric Properties of Mn-Doped BaTi2O5 Ceramics

概要

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High-density ceramics of BaTi2O5 have been fabricated by a conventional sintering method using both sol--gel-derived BaTi2O5 powders and MnO2 additives of 0.2--0.8 wt %. The effects of sintering conditions on the densification, microstructural evolution and dielectric properties are investigated. As the effect of Mn addition, the BaTi2O5 phase becomes stable at least up to 1250 °C, and a significant densification is achieved at temperatures as low as 1200--1250 °C. The dielectric constant $\varepsilon '$ vs temperature $T$ curve of the MnO2-added ceramics exhibits a broad maximum $\varepsilon'{}_{\text{max}}$ at the ferroelectric phase transition temperature $T_{\text{C}}$, which is 140 °C lower than that of the nondoped ceramics. Among the ceramics with different Mn contents, the 0.2 wt % MnO2-added ceramics have the largest $\varepsilon'{}_{\text{max}}$ of 470 at 328 °C and the smallest $\tan\delta$ of ${<}0.05$ at a high temperature of around 520 °C at 1 MHz. We observed a ferroelectric $D$--$E$ hysteresis loop for the first time in the polycrystalline form of BaTi2O5.
2011-09-25