Defect chemistry engineering and thermal treatment on dislocation mechanics in SrTiO3

SrTiO3 位错力学的缺陷化学工程和热处理

• 批准号: 510801687
• 负责人: Dr.-Ing. Xufei Fang
• 金额: --
• 依托单位: Fachgebiet Physikalische Metallkunde
• 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/510801687?language=en
• 关键词: Defect; chemistry; engineering; thermal; treatment

The properties of modern functional oxides can be tailored by selectively changing the defect chemistry, i.e. by introducing point defects. This usually involves the introduction of charges into the crystal lattice. An alternative approach to modifying functional properties is the introduction of dislocations. Dislocations are line defects, which can be strongly charged in oxides, thus interacting with point defects. In recent years, this new approach has attracted increasing research interest. Promising proofs-of-concept have shown that the functional properties of oxides, such as electrical conductivity, thermal conductivity, and superconductivity, can be selectively influenced by changing the dislocation structure. Ceramics are typically processed at high temperatures, with the point defects present being frozen far from thermodynamic equilibrium during cooling. For this reason, interactions inevitably occur between the introduced dislocations and the numerous point defects in ceramic oxides. Therefore, the following scientifically relevant questions arise:1) Are the mechanical properties, such as plasticity and cracking behavior, altered by the interaction of dislocations and point defects?2) How do point defects interact with previously introduced dislocations as a function of temperature and heating/cooling rate, the latter affecting thermodynamic equilibrium?3) What is the contribution of the electrostatic fields of line and point defects to solid solution hardening? How does a change in the defect chemistry of the sample affect dislocation mobility?In this project, we aim to answer these questions and shed new light on the thermal stability of dislocations and its influence on mechanical properties, which is crucial for dislocation-controlled functionality as well as mechanical reliability of components. For this purpose, single-crystalline SrTiO3 (with different conditions of defect chemistry) will be used as a reference material and nanong-/micromechanical tests will be performed at different temperatures to study 1) dislocation nucleation and multiplication modified by point defects. Furthermore, 2) the interaction between the generated dislocations and point defects affecting the dislocation motion will be investigated. In addition to plasticity, the cracking behavior (crack formation and propagation) of the materials will also be studied, taking into account the dislocation behavior.

现代功能氧化物的特性可以通过选择性更改缺陷化学（即引入点缺陷）来量身定制。这通常涉及将电荷引入晶格。修改功能特性的另一种方法是引入位错。位错是线缺陷，可以在氧化物中强烈充电，从而与点缺陷相互作用。近年来，这种新方法吸引了越来越多的研究兴趣。有前途的概念证明表明，氧化物的功能特性，例如电导率，导热率和超导性，可以通过改变位错结构来选择性地影响。陶瓷通常在高温下进行处理，而在冷却过程中，存在点缺陷远离热力学平衡。因此，在引入的位错和陶瓷氧化物中的众多点缺陷之间不可避免地发生相互作用。因此，出现以下科学相关问题：1）通过位错和点缺陷的相互作用改变了机械性能，例如可塑性和开裂行为？2）点缺陷如何与先前引入的脱位相互作用，作为温度和温度和加热/冷却速率，后者影响热力学平衡？3）线和点缺陷对固体溶液硬化的静电场和点缺陷的贡献是什么？样品缺陷化学的变化如何影响脱位迁移率？在这个项目中，我们旨在回答这些问题，并为位错的热稳定性及其对机械性能的影响提供新的启示，这对于脱位控制功能至关重要以及组件的机械可靠性。为此，单晶SRTIO3（具有不同缺陷化学条件）将用作参考材料，并将在不同的温度下进行研究。此外，2）将研究影响脱位运动的生成位错和点缺陷之间的相互作用。除了可塑性外，还要考虑到脱位行为，还将研究材料的开裂行为（裂纹形成和传播）。