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Mesoscopic-scale transformation processes in Bi-based perovskite-type ferroelectric solid solutions

Bi基钙钛矿型铁电固溶体的介观尺度转变过程

基本信息

批准号：
269878195
负责人：
Professorin Dr. Boriana Mihailova
金额：
--
依托单位：
Mineralogisch-Petrographisches Institut (MPI)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2015
资助国家：
德国
起止时间：
2014-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/269878195?language=en
关键词：
Mesoscopic scale transformation processes Bi

项目摘要

Our modern life is unthinkable without ferroelectrics:materials with spontaneous polarization switchable under an external electric field, which exhibit large dielectric permittivity as well as strong piezoelectric, pyroelectric and optoelectric responses. The majority of advanced ferroelectrics are perovskite-type (ABO3) solid solutions possessing a morphotropic phase boundary (MPB): a critical composition x at which the symmetry of the ferroelectric long-range order changes and the properties are strongly amplified. It is well known that in the vicinity of MPB there are abundant nanoscale structural inhomogeneities. However, although the enormous efforts over the past decades to establish a generalized atomistic model of the relation composition - structure – properties, the driving mechanism of chemically induced structural instability and enhanced macroproperties near MPB is still not clarified. The quest to find environmentally friendly Pb-reduced or Pb-free alternatives of the famous PbZrxTi1-xO3 has led to an increasing interest in Bi-based perovskite-type ferroelectrics. A thorough study of the composition dependence of the local structure and atomic dynamics in novel Bibased solid solutions using Raman spectroscopy and total neutron scattering was the subject of project MI 1127/8-1. The results obtained so far reveal that the larger piezoelectric response at the MPB is due to the increased synchronization between the A- and B-site cation vibrations. The superior piezoelectric properties in specific ABO3-type solid solutions result from to the absolute flattening of the local potentials for all ferroelectrically active cations preserving relatively high polar displacements at MPB. The major goal of this continuation project is to complete the comparative study on the mesoscopic-scale transformation processes in (1-x)PbTiO3-xBiMeO3 solid solutions with Me = Mg0.5Ti0.5, Ni0.5Ti0.5, Ni0.5Zr0.5. For each series four selected compounds across the MPB are going to be analyzed by Raman spectroscopy and pair-distribution-function analyses complemented by reverse Monte Carlo simulations in a wide temperature range, including high temperatures well above the Curie temperature. The results are expected to clarify the atomistic driving forces of formation of highly disordered structural state at the MPB, as revealed from our analyses at room temperature. The comparative analyses of the renomalization phenomena will considerably improve our understanding of the microscopic origin of the dependence of the Curie temperature and piezoelectric coefficients on the type of the dopant and thus, may have critical effect on the strategy of designing novel functional materials.

我们的现代生活没有铁电体是不可想象的：具有自发极化的材料在外电场下可切换，具有大的介电常数以及强的压电，热释电和光电响应。大多数先进的铁电体是钙钛矿型（ABO3）固溶体，具有形态取向相边界（MPB）：在这一临界成分x下，铁电长程有序的对称性发生了变化，性能被强烈放大。众所周知，在MPB附近存在丰富的纳米级结构不均匀性。然而，尽管在过去几十年里，人们为建立组成-结构-性能关系的广义原子模型做出了巨大的努力，但在MPB附近化学诱导结构不稳定和宏观性能增强的驱动机制仍然不清楚。寻找著名的PbZrxTi1-xO3的环保减铅或无铅替代品的探索，导致人们对铋基钙钛矿型铁电体的兴趣日益浓厚。利用拉曼光谱和全中子散射深入研究新型双基固溶体中局部结构和原子动力学的组分依赖性是MI 1127/8-1项目的主题。迄今为止获得的结果表明，MPB上较大的压电响应是由于A-和b -位点阳离子振动之间的同步增加。在特定abo3型固溶体中优异的压电性能是由于所有铁电活性阳离子的局部电位绝对平坦，在MPB处保持相对较高的极性位移。本延续项目的主要目标是完成Me = Mg0.5Ti0.5, Ni0.5Ti0.5, Ni0.5Zr0.5的（1-x）PbTiO3-xBiMeO3固溶体中介观尺度转化过程的比较研究。通过拉曼光谱和配对分布函数分析，并辅以反向蒙特卡罗模拟，在广泛的温度范围内（包括远高于居里温度的高温）对MPB中每个系列的四个选定化合物进行分析。这一结果有望阐明在室温下MPB中形成高度无序结构态的原子驱动力。对重归一化现象的比较分析将大大提高我们对居里温度和压电系数对掺杂类型依赖的微观根源的理解，从而可能对设计新型功能材料的策略产生关键影响。