It is well known that diamond does not deform plastically at room temperature and usually fails in catastrophic brittle fracture. Here we demonstrate room-temperature dislocation plasticity in sub-micrometer sized diamond pillars by in-situ mechanical testing in the transmission electron microscope. We document in unprecedented details of spatio-temporal features of the dislocations introduced by the confinement-free compression, including dislocation generation and propagation. Atom-resolved observations with tomographic reconstructions show unequivocally that mixed-type dislocations with Burgers vectors of 1/2<110> are activated in the non-close-packed {001} planes of diamond under uniaxial compression of <111> and <110> directions, respectively, while being activated in the {111} planes under the <100> directional loading, indicating orientation-dependent dislocation plasticity. These results provide new insights into the mechanical behavior of diamond and stimulate reconsideration of the basic deformation mechanism in diamond as well as in other brittle covalent crystals at low temperatures.
@article{arxiv.2002.05913,
title = {Direct Observation of Room-Temperature Dislocation Plasticity in Diamond},
author = {Anmin Nie and Yeqiang Bu and Junquan Huang and Yecheng Shao and Yizhi Zhang and Wentao Hu and Jiabin Liu and Yanbin Wang and Bo Xu and Zhongyuan Liu and Hongtao Wang and Wei Yang and Yongjun Tian},
journal= {arXiv preprint arXiv:2002.05913},
year = {2020}
}