Zhang Zhidong, Yang Bin, Chen Longyu, Zhang Zaoli, Guo Jinming
Hubei Key Laboratory of Polymer Materials, Ministry-of-Education Key Laboratory of Green Preparation and Application for Functional Materials, School of Materials Science and Engineering, Hubei University, Wuhan, 430062, China.
Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Leoben, 8700, Austria.
Nat Commun. 2025 Jul 31;16(1):7015. doi: 10.1038/s41467-025-62424-3.
Dislocations are emerging as a pivotal factor for tailoring ceramics' functional and mechanical properties. The introduction of point defects, notably oxygen vacancies, is unavoidable during the conventional sintering process in polycrystalline ceramics. Understanding the interplay between dislocations and oxygen vacancies is necessary for its profound implications. This work implements an innovative approach to regulate the dislocation-based incipient plasticity and creep behavior in (KNa)NbO-based ceramics through oxygen vacancy engineering via CuO "hard" doping. Nanoindentation pop-in tests reveal that increasing oxygen vacancy concentrations significantly promotes the nucleation and activation of dislocations. Theoretical calculations based on density functional theory further corroborate that oxygen vacancies contribute to a decrease in Peierls stress and total misfit energy, facilitating dislocation nucleation and activation. Nanoindentation hardness and creep behavior demonstrate that oxygen vacancy impedes dislocation mobility due to solute strengthening and pinning effects. The effect of oxygen vacancies is elucidated through diverse mechanisms related to the interaction between dislocations and oxygen vacancies at different stages. This oxygen vacancy-induced strengthening and toughening strategy displays a significant potential to improve the mechanical properties of piezoelectric ceramics, while still maintaining high electrical performance.
位错正逐渐成为定制陶瓷功能和力学性能的关键因素。在多晶陶瓷的传统烧结过程中，引入点缺陷（尤其是氧空位）是不可避免的。理解位错与氧空位之间的相互作用因其深远影响而十分必要。这项工作采用了一种创新方法，通过CuO“硬”掺杂的氧空位工程来调控（KNa）NbO基陶瓷中基于位错的初始塑性和蠕变行为。纳米压痕突跳测试表明，增加氧空位浓度会显著促进位错的形核与激活。基于密度泛函理论的理论计算进一步证实，氧空位会导致派尔斯应力和总错配能降低，从而促进位错形核与激活。纳米压痕硬度和蠕变行为表明，由于溶质强化和钉扎效应，氧空位会阻碍位错迁移。通过位错与氧空位在不同阶段相互作用的多种机制阐明了氧空位的作用。这种氧空位诱导的强化增韧策略在改善压电陶瓷力学性能的同时仍保持高电学性能方面显示出巨大潜力。
