Elasticity and piezoelectricity of zinc oxide crystals, single layers, and possible single-walled nanotubes

TL;DR

This study uses first-principles calculations to explore the elasticity and piezoelectricity of zinc oxide in various forms, revealing structural preferences, flexibility, and potential for nanotube formation with chirality-dependent properties.

Contribution

It introduces the theoretical prediction of stable single-walled ZnO nanotubes and their piezoelectric behavior based on chirality, expanding the understanding of ZnO nanostructures.

Findings

ZnO thin films less than three layers prefer a graphite-like structure.

ZnO single layers are more flexible than graphite and more piezoelectric than boron nitride.

Single-walled ZnO nanotubes can exist with chirality-dependent piezoelectric properties.

Abstract

The elasticity and piezoelectricity of zinc oxide (ZnO) crystals and single layers are investigated from the first-principles calculations. It is found that a ZnO thin film less than three Zn-O layers prefers a planar graphite-like structure to the wurtzite structure. ZnO single layers are much more flexible than graphite single layers in the elasticity and stronger than boron nitride single layers in the piezoelectricity. Single-walled ZnO nanotubes (SWZONTs) can exist in principle because of their negative binding energy. The piezoelectricity of SWZONTs depends on their chirality. For most ZnO nanotubes except the zigzag type, twists around the tube axis will induce axial polarizations. A possible scheme is proposed to achieve the SWZONTs from the solid-vapor phase process with carbon nanotubes as templates.