Oliveira Leonardo, Ormstrup Jeppe, Majkut Marta, Makarovic Maja, Rojac Tadej, Walker Julian, Simons Hugh
Department of Physics, Technical University of Denmark 2800 Kgs. Lyngby Denmark
ESRF - The European Synchrotron, Avenue des Martyrs 38000 Grenoble France.
J Mater Chem C Mater. 2023 Apr 14;11(21):6902-6911. doi: 10.1039/d2tc05100a. eCollection 2023 Jun 1.
While BiFeO-based solid solutions show great promise for applications in energy conversion and storage, realizing this promise necessitates understanding the structure-property relationship in particular pertaining to the relaxor-like characteristics often exhibited by solid solutions with polar-to-non-polar morphotropic phase boundaries. To this end, we investigated the role of the compositionally-driven relaxor state in (100 - )BiFeO-SrTiO [BFO-STO], synchrotron X-ray diffraction under bipolar electric-field cycling. The electric-field induced changes to the crystal structure, phase fraction and domain textures were monitored the {111}, {200}, and 1/2{311} Bragg peaks. The dynamics of the intensities and positions of the (111) and (111̄) reflections reveal an initial non-ergodic regime followed by long-range ferroelectric ordering after extended poling cycles. The increased degree of random multi-site occupation in BFO-42STO compared to BFO-35STO is correlated with an increase of the critical electric field needed to induce the non-ergodic-to-ferroelectric transition, and a decrease in the degree of domain reorientation. Although both compositions show an irreversible transition to a long-range ferroelectric state, our results suggest that the weaker ferroelectric response in BFO-42STO is related to an increase in ergodicity. This, in turn, serves to guide the development of BFO-based systems into promising platform for further property engineering towards specific capacitor applications.
虽然基于铋铁氧体的固溶体在能量转换和存储应用中显示出巨大潜力，但要实现这一潜力，就需要了解结构-性能关系，特别是与具有极性-非极性准同型相界的固溶体经常表现出的类弛豫特性相关的关系。为此，我们研究了在双极电场循环下，（100 - ）BiFeO-SrTiO [BFO-STO] 中成分驱动的弛豫态的作用，通过同步加速器X射线衍射进行研究。监测了在 {111}、{200} 和 1/2{311} 布拉格峰处电场诱导的晶体结构、相分数和畴织构的变化。（111）和（111̄）反射的强度和位置的动力学揭示了一个初始的非遍历区域，随后在长时间极化循环后出现长程铁电有序。与BFO-35STO相比，BFO-42STO中随机多位点占据程度的增加与诱导非遍历到铁电转变所需的临界电场的增加以及畴重新取向程度的降低相关。尽管两种成分都显示出向长程铁电态的不可逆转变，但我们的结果表明，BFO-42STO中较弱的铁电响应与遍历性的增加有关。这反过来又有助于将基于BFO的系统发展成为一个有前途的平台，用于进一步针对特定电容器应用进行性能工程。
