Pr和Nb共掺杂Bi_4Ti_3O_(12)陶瓷材料电行为特性研究

Electrical Behavior of Pr and Nb Co-doped Bi_4Ti_3O_(12) Ceramics

采用高温固相法制备了Pr和Nb共掺杂Bi4Ti3O12铁电陶瓷。利用XRD分析表征了样品物相结构,利用阻抗分析仪和铁电性能测量仪测试了样品的电性能,并通过对样品电导率与温度的关系进行Arrhenius拟合分析了材料的导电机理。结果表明:Pr和Nb已经完全固溶进入Bi4Ti3O12晶格中,制备的样品均为单一的层状钙钛矿结构。Nb的引入使样品的介电常数变大,介电损耗明显降低,但居里温度变化不大。在Nb掺杂量较小(x≤0.09)时,材料的剩余极化值随着Nb掺杂量增加而增大,当x=0.09时2Pr达到极大值为26μC/cm2,矫顽场为50.3kV/cm。这主要是由于高价态的Nb5+取代B位Ti4+能有效的抑制氧空位的产生。

Pr and Nb co-doping Bi4Ti3O12 layer-structured ferroeectric ceramics were prepared by the solid-state reaction method.The microstructures of the samples were analyzed by X-ray diffraction.The dielectric and ferroelectric properties of samples were investigated and electronic conductor mechanism of Bi2.9Pr0.9Ti3-xNbxO12＋x/2 was analyzed by the Arrhenius fit of direct current conductivity vs temperature.It was found that all the polycrystalline ceramics have almost a single phase,which indicated that the substitution of Nb5＋ did not affect largely the Bi-layered perovskite structure.By Nb5＋ doping,dielectric constants of Bi2.9Pr0.9Ti3-xNbxO12＋x/2 ceramics increase and the loss tangents of samples were much lower,but the decrease in the Curie temperature was very limited.At a small Nb doping of x≤0.09,the remanent polarization （Pr） increased.The 2Pr and coercive field of the sample （x=0.09 ） were 26 μC/cm2 and 50.3 kV/cm,respectively.That is mainly due to the substitution of Ti4＋ by Nb5＋ at the B site,which made the concentration of oxygen vacancies decreased.