Effect of strain induced charge redistribution on Young's modulus of zinc oxide nanowires

As the size of material decreases to nanoscale, fundamental material properties such as Young's modulus are different from bulk values. In this paper, we propose a new mechanism to explain the difference in experimentally observed Young's modulus values between zinc oxide nanowires and bulk zinc oxide. As a binary compound material (such as zinc oxide) is strained, the effective charge on the ionic constituents of the material changes (in this case zinc and oxygen). The strain induced charge redistribution effect is more significant in nanostructures (such as nanowires) because of their higher fracture strains compared to their bulk counterparts. Since the Young's modulus of a material is related to the effective charge, we observe differences in modulus values between nanowires and their bulk equivalent. The strain induced charge redistribution phenomenon can also be used to explain variation in modulus values between bulk and nanoscale for other single crystal piezoelectric materials such as silicon carbide.