Ultra-dense dislocations stabilized in high entropy oxide ceramics

Yi Han; Xiangyang Liu; Qiqi Zhang; Muzhang Huang; Yi Li; Wei Pan; Peng-An Zong; Lieyang Li; Zesheng Yang; Yingjie Feng; Peng Zhang; Chunlei Wan

doi:10.1038/s41467-022-30260-4

Ultra-dense dislocations stabilized in high entropy oxide ceramics

Nat Commun. 2022 May 24;13(1):2871. doi: 10.1038/s41467-022-30260-4.

Authors

Yi Han^#¹, Xiangyang Liu^#¹, Qiqi Zhang², Muzhang Huang¹, Yi Li¹, Wei Pan³, Peng-An Zong¹, Lieyang Li¹, Zesheng Yang¹, Yingjie Feng¹, Peng Zhang^{4

5}, Chunlei Wan⁶

Affiliations

¹ State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, 100084, Beijing, China.
² National Center for Electron Microscopy in Beijing, 100084, Beijing, China.
³ State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, 100084, Beijing, China. panw@mail.tsinghua.edu.cn.
⁴ State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, 100084, Beijing, China. peng.zhang@bjut.edu.cn.
⁵ Institute of Welding and Surface Engineering Technology, Faculty of Materials and Manufacturing, Beijing University of Technology, 100124, Beijing, China. peng.zhang@bjut.edu.cn.
⁶ State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, 100084, Beijing, China. wancl@mail.tsinghua.edu.cn.

^# Contributed equally.

Abstract

Dislocations are commonly present and important in metals but their effects have not been fully recognized in oxide ceramics. The large strain energy raised by the rigid ionic/covalent bonding in oxide ceramics leads to dislocations with low density (∼10⁶ mm^-²), thermodynamic instability and spatial inhomogeneity. In this paper, we report ultrahigh density (∼10⁹ mm^-2) of edge dislocations that are uniformly distributed in oxide ceramics with large compositional complexity. We demonstrate the dislocations are progressively and thermodynamically stabilized with increasing complexity of the composition, in which the entropy gain can compensate the strain energy of dislocations. We also find cracks are deflected and bridged with ∼70% enhancement of fracture toughness in the pyrochlore ceramics with multiple valence cations, due to the interaction with enlarged strain field around the immobile dislocations. This research provides a controllable approach to establish ultra-dense dislocations in oxide ceramics, which may open up another dimension to tune their properties.

Grants and funding

52022042/National Science Foundation of China | National Natural Science Foundation of China-Yunnan Joint Fund (NSFC-Yunnan Joint Fund)