ABSTRACT

Low-levels of Nb-doped (≤2 at.%) NBT ceramics were synthesized using a conventional ceramic technique. The XRD analysis indicated the formation of a perovskite structure with rhombohedral symmetry where Nb-doping tends to expand the lattice. The dielectric characteristics and piezoelectric coupling are enhanced as a result of microdefect dipole and ferroelectric order disturbance. It was shown that E-poling influences the properties under investigation. This includes a decrease of electric permittivity (ϵ) and an increase of depolarization temperature T_d and temperature T_m at which ϵ is the maximum. This is accompanied by the increase of tetragonal regions at the cost of rhombohedral phase (visible in the Raman spectra) and redistribution of the microdefect dipoles, hence ferroelectric order.

摘要

使用传统陶瓷技术合成低含量 Nb 掺杂 (≤ 2 at.%) NBT 陶瓷。XRD 分析表明形成了具有菱面体对称性的钙钛矿结构，其中 Nb 掺杂倾向于扩展晶格。由于微缺陷偶极子和铁电有序干扰，介电特性和压电耦合得到增强。结果表明，E-极化会影响所研究的特性。这包括介电常数 ( ϵ )的降低和去极化温度T _d和温度T _{m 的增加}，其中ϵ是最大值。这伴随着以菱形相（在拉曼光谱中可见）为代价的四方区域的增加和微缺陷偶极子的重新分布，因此铁电有序。