Li Yi, Liu Xiangyang, Zhang Peng, Han Yi, Huang Muzhang, Wan Chunlei
State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, 100084, Beijing, China.
College of Mathematics and Physics, Beijing University of Chemical Technology, 100029, Beijing, China.
Nat Commun. 2022 Nov 14;13(1):6925. doi: 10.1038/s41467-022-34741-4.
An in-depth understanding of the dislocations motion process in non-metallic materials becomes increasingly important, stimulated by the recent emergence of ceramics and semiconductors with unexpected room temperature dislocation-mediated plasticity. In this work, local misfit energy is put forward to accurately derive the Peierls stress and model the dislocation process in SrTiO ceramics instead of the generalized stacking fault (GSF) approach, which considers the in-plane freedom degrees of the atoms near the shear plane and describes the breaking and re-bonding processes of the complex chemical bonds. Particularly, we discover an abnormal shear-dependence of local misfit energy, which originates from the re-bonding process of the Ti-O bonds and the reversal of lattice dipoles. In addition, this approach predicts that oxygen vacancies in the SrTiO can facilitate the nucleation and activation of dislocations with improvement of fracture toughness, owing to the reduction of average misfit energy and Peierls stress due to the disappearance of lattice dipole reversal. This work provides undiscovered insights into the dislocation process in non-metallic materials, which may bring implications to tune the plasticity and explore unknown ductile compositions.
随着近来具有意外室温位错介导可塑性的陶瓷和半导体的出现，深入了解非金属材料中位错的运动过程变得越来越重要。在这项工作中，提出了局部错配能来精确推导派尔斯应力并模拟SrTiO陶瓷中的位错过程，而不是采用广义堆垛层错（GSF）方法，后者考虑了剪切面附近原子的面内自由度并描述了复杂化学键的断裂和重新键合过程。特别地，我们发现了局部错配能的异常剪切依赖性，这源于Ti-O键的重新键合过程和晶格偶极子的反转。此外，该方法预测，SrTiO中的氧空位可促进位错的形核和激活，并提高断裂韧性，这是由于晶格偶极子反转消失导致平均错配能和派尔斯应力降低。这项工作为非金属材料中的位错过程提供了未被发现的见解，这可能对调节可塑性和探索未知的韧性成分带来启示。
