title: Elastic properties of GaN nanowires: revealing the influence of planar defects on young's modulus at nanoscale.
abstract: The elastic properties of gallium nitride (GaN) nanowires with different structures were investigated by in situ electron microscopy in this work. The electric-field-induced resonance method was utilized to reveal that the single crystalline GaN nanowires, along [120] direction, had the similar Young's modulus as the bulk value at the diameter ranging 92-110 nm. Meanwhile, the elastic behavior of the obtuse-angle twin (OT) GaN nanowires was disclosed both by the in situ SEM resonance technique and in situ transmission electron microscopy tensile test for the first time. Our results showed that the average Young's modulus of these OT nanowires was greatly decreased to about 66 GPa and indicated no size dependence at the diameter ranging 98-171 nm. A quantitative explanation for this phenomenon is proposed based on the rules of mixtures in classical mechanics. It is revealed that the elastic modulus of one-dimensional nanomaterials is dependent on the relative orientations and the volume fractions of the planar defects.
authors.affiliation: Beijing National Center for Electron Microscopy, The State Key Laboratory of New Ceramics and Fine Processing, Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University , Beijing 100084, China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Dai
authors.forename: Jiong
authors.initials: J
authors.lastname: Zhao
authors.forename: Mo-rigen
authors.initials: MR
authors.lastname: He
authors.forename: Xiaoguang
authors.initials: X
authors.lastname: Wang
authors.forename: Jingchun
authors.initials: J
authors.lastname: Wan
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Shan
authors.forename: Jing
authors.initials: J
authors.lastname: Zhu
mesh_terms: D055119:Elastic Modulus; D005708:Gallium / Q000737:chemistry*; D053770:Nanowires / Q000737:chemistry*
chemical_list: C473348:gallium nitride; D005708:Gallium
keywords: GaN nanowires; Young’s modulus; elastic behavior; in situ electron microscopy; planar defects