Prediction, synthesis, and characterization of novel ferroelectric metal fluorides

新型铁电金属氟化物的预测、合成和表征

• 批准号: 533629173
• 负责人: Professor Dr. Florian Kraus
• 金额: --
• 依托单位: Institut für Allgemeine, Anorganische und Theoretische Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/533629173?language=en
• 关键词: Prediction; synthesis; characterization; novel; ferroelectric

Ferroelectrics are insulators with a spontaneous electric polarization that can be reversed by an external electric field. Their properties make them desirable functional materials with broad application potential, ranging from energy converters or sensors to random access memory in information technology. The occurrence of ferroelectricity is linked to strict structural requirements. Spontaneous polarization is only possible in polar space groups belonging to the ten pyroelectric crystal classes. In addition, the reversal of the polarization direction must occur via a paraelectric isotropy supergroup. These structural requirements were summarized by Abrahams into empirical rules and are still the basis for predicting previously unknown ferroelectrics. Historically, the focus of research has been on oxide ferroelectrics. Nowadays, a large number of oxide ferroelectric structure types are known, but only a few fluoride compounds with this property. In the present project, we aim to predict novel ferroelectric fluorides. For this purpose, we will prepare a survey of polar metal fluorides, which we will investigate for their potential as ferroelectrics using the successful Abrahams crystallographic criteria in combination with modern quantum chemical methods. We will synthesize and characterize promising candidates from this survey to demonstrate their structural prerequisites for ferroelectricity. Via an initial screening of the Pearson database, we have succeeded in identifying 105 different polar structure types for metal fluorides. Only nine of these structure types have at least one representative that is proven to be ferroelectric. Thus, a high potential for previously unknown ferroelectrics exists here. So far, we have already identified three promising candidates for new potentially ferroelectric structure types with β-MnF4 (R3c, hR360), Mn3F8 (P21, mS22) and RbCrF5 (Pmc21, oP28), with which we can start our work. Our screening further reveals that controversial structure proposals exist for about 30% of the structure types. This is because, especially for polar compounds, the assignment of the space group in the diffraction experiment is not always possible without doubt. This complicates automatic compilations of data sets needed for high-throughput DFT calculations or machine learning. This aspect highlights the great need for an unambiguous structural chemical data set for polar compounds. With the crystallographic, structural chemical and experimental experience knowledge of our working group we want to tackle this task for the material class of metal fluorides.

铁电基因是具有赞助电动极化的绝缘体，外部电场可以逆转。它们的特性使其具有广泛应用潜力的理想功能材料，从能量转换器或传感器到信息技术中的随机访问记忆。铁电性的发生与严格的结构要求有关。只有在属于十个高电晶体类别的极性空间群中才有可能自发极化。另外，偏振方向的反向必须通过降落式各向异性超组发生。亚伯拉罕将这些结构要求总结为经验规则，并且仍然是预测先前未知的铁电的基础。从历史上看，研究的重点一直是氧化物铁电的。如今，已知大量的氧化物铁电结构类型，但只有几种具有该特性的氟化物化合物。在本项目中，我们旨在预测新型的铁电氟化物。为此，我们将准备对极性金属氟化物的调查，我们将使用成功的亚伯拉罕晶体学标准与现代量子化学方法结合使用，以研究其作为铁电的潜力。我们将合成并表征本调查中的承诺候选人，以证明其结构性铁电性的先决条件。通过对Pearson数据库的初始筛选，我们成功地识别了105种不同的极性结构类型的金属氟化物类型。这些结构类型中只有九种至少一种代表被证明是铁电是。这是这里存在的高潜力。到目前为止，我们已经确定了具有β-MNF4（R3C，HR360），MN3F8（P21，MS22）和RBCRF5（PMC21，OP28）的新潜在铁电结构类型的三个承诺候选者，并从中可以开始我们的工作。我们的筛选进一步表明，有争议的结构建议存在约30％的结构类型。这是因为尤其是对于极性化合物，毫无疑问，衍射实验中空间群的分配并非总是可能。这使高通量DFT计算或机器学习所需的数据集自动汇编复杂。方面强调了对极性化合物的明确结构化学数据集的巨大需求。借助我们工作组的晶体学，结构化学和实验经验知识，我们希望针对金属氟化物的材料类别解决这项任务。