文摘
Multiferroic ceramics of (0.70?x)BiFeO3-.30BaTiO3–xBi(Zn0.5Ti0.5)O3?+?1?mol%?MnO2 with perovskite structure were prepared by a conventional ceramic technique and the effects of Bi(Zn0.5Ti0.5)O3 doping and sintering temperature on the microstructure, multiferroic and piezoelectric properties of the ceramics were studied. All the ceramics possess a pure perovskite structure and no second phases can be detected. After the addition of a small amount of Bi(Zn0.5Ti0.5)O3 (x?≤?.05), the ferroelectric and piezoelectric properties of the ceramics are improved and the grain growth is promoted. However, excess Bi(Zn0.5Ti0.5)O3 (x?≥?.10) retards the grain growth, degrades the ferroelectricity and piezoelectricity, and induces two dielectric anomalies at high temperature. The ceramics can be well sintered at the very wide range of low sintering temperatures (880-80?°C) and exhibit good densification (relative density: 96.2-8.4?%) and strong electric insulation. The increase in the sintering temperature promotes the grain growth and improves the ferroelectricity of the ceramics. The ceramic with x?=?0.05 sintered at 880-80?°C possesses improved ferroelectric and piezoelectric properties with remanent polarizations P r of 21.9-8.1?μm/cm2, piezoelectric constants d 33 of 125-39?pC/N and planar electromechanical coupling factors k p of 30.1-2.4?%, and high Curie temperatures T C of 523-65?°C. A weak ferromagnetism with remanent magnetizations M r of 0.0411-.0422?emu/g and coercive fields H c of 1.70-.99?kOe were observed in the ceramics with x?=?0-.025.