title: Large anelasticity and associated energy dissipation in single-crystalline nanowires.
abstract: Anelastic materials exhibit gradual full recovery of deformation once a load is removed, leading to dissipation of internal mechanical energy. As a consequence, anelastic materials are being investigated for mechanical damping applications. At the macroscopic scale, however, anelasticity is usually very small or negligible, especially in single-crystalline materials. Here, we show that single-crystalline ZnO and p-doped Si nanowires can exhibit anelastic behaviour that is up to four orders of magnitude larger than the largest anelasticity observed in bulk materials, with a timescale on the order of minutes. In situ scanning electron microscope tests of individual nanowires showed that, on removal of the bending load and instantaneous recovery of the elastic strain, a substantial portion of the total strain gradually recovers with time. We attribute this large anelasticity to stress-gradient-induced migration of point defects, as supported by electron energy loss spectroscopy measurements and also by the fact that no anelastic behaviour could be observed under tension. We model this behaviour through a theoretical framework by point defect diffusion under a high strain gradient and short diffusion distance, expanding the classic Gorsky theory. Finally, we show that ZnO single-crystalline nanowires exhibit a high damping merit index, suggesting that crystalline nanowires with point defects are promising materials for energy damping applications.
authors.affiliation: Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA.
authors.forename: Guangming
authors.identifier: 0000000158521341
authors.initials: G
authors.lastname: Cheng
authors.affiliation: 1] School of Engineering, Brown University, Providence, Rhode Island 02912, USA [2] Institute of Nano Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China.
authors.forename: Chunyang
authors.initials: C
authors.lastname: Miao
authors.affiliation: Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA.
authors.forename: Qingquan
authors.initials: Q
authors.lastname: Qin
authors.affiliation: Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA.
authors.forename: Feng
authors.initials: F
authors.lastname: Xu
authors.affiliation: School of Engineering, Brown University, Providence, Rhode Island 02912, USA.
authors.forename: Hamed
authors.initials: H
authors.lastname: Haftbaradaran
authors.affiliation: Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA.
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Dickey
authors.affiliation: School of Engineering, Brown University, Providence, Rhode Island 02912, USA.
authors.forename: Huajian
authors.initials: H
authors.lastname: Gao
authors.affiliation: 1] Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA [2] Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhu