Nanoscale compositional segregation and suppression of polar coupling in a relaxor ferroelectric
Nanoscale compositional segregation and suppression of polar coupling in a relaxor ferroelectric
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DOI：
10.1016/j.actamat.2018.07.053
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发表时间：
2018-10
期刊：
影响因子：
9.4
通讯作者：
T. Roncal-Herrero;J. Harrington;A. Zeb;S. J. Milne;Andy P. Brown
中科院分区：
文献类型：
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作者：
T. Roncal-Herrero;J. Harrington;A. Zeb;S. J. Milne;Andy P. Brown
许多弛豫铁电陶瓷已被证明在很宽的温度范围内具有接近稳定的相对介电常数值。这不能用松弛剂的传统理论来解释。一种这样的体系是基于钙钛矿固溶体系列：（1-x） （Ba0.8Ca0.2）TiO3-xBi(Mg0.5Ti0.5)O3，在150至500 °C之间具有稳定的相对介电常数。我们通过扫描透射电子显微镜和电子能量损失光谱元素图显示，纳米级的成分偏析发生在温度稳定的弛豫成分中（x = 0.55），Ba/Ti团簇的范围约为2-4 nm，由相当大小的富bi区域隔开。这种纳米微粒结构与相分离相一致，相分离为铁电活性BaTiO3 -型相（富Ba/Ti）和弱极性富Bi/(Mg)钙钛矿固溶体。考虑了纳米相偏析是弱偶极子耦合和抑制介电弛豫峰的可能原因。
A number of relaxor ferroelectric ceramics have been demonstrated to possess a near stable value of relative permittivity over very wide temperature ranges. This cannot be explained by conventional theories of relaxors. One such system is based on the perovskite solid solution series: (1-x) (Ba0.8Ca0.2)TiO3-xBi(Mg0.5Ti0.5)O3, giving stable relative permittivity from 150 to 500 °C. We show by scanning transmission electron microscopy and electron energy loss spectroscopic elemental mapping that nanoscale compositional segregation occurs in the temperature stable relaxor composition (x = 0.55), with Ba/Ti clusters some 2–4 nm in extent, separated by Bi-rich regions of comparable size. This nanomosaic structure is consistent with phase separation into a ferroelectrically active BaTiO3– type phase (Ba/Ti rich) and a weakly polar Bi/(Mg) rich perovskite solid solution. The possibility that nanophase segregation is the cause of weak dipole coupling and suppression of the dielectric relaxation peak is considered.