Novel Two-Dimensional Silicon Dioxide with in-plane Negative Poisson's Ratio

TL;DR

This study discovers three new stable two-dimensional silica structures with in-plane negative Poisson's ratios and wide electronic band gaps, revealing their potential for nanomechanics and nanoelectronics applications.

Contribution

We identify novel 2D silica structures with large negative Poisson's ratios and high electronic band gaps using ab initio calculations and evolutionary algorithms.

Findings

All three 2D silica structures have large in-plane negative Poisson's ratios.

The widest electronic band gap among 2D silica is over 7 eV.

Negative Poisson's ratio arises from lattice and Si-O tetrahedron symmetry interplay.

Abstract

Silicon dioxide or silica, normally existing in various bulk crystalline and amorphous forms, is recently found to possess a two-dimensional structure. In this work, we use ab initio calculation and evolutionary algorithm to unveil three new 2D silica structures whose themal, dynamical and mechanical stabilities are compared with many typical bulk silica. In particular, we find that all these three 2D silica have large in-plane negative Poisson's ratios with the largest one being double of penta-graphene and three times of borophenes. The negative Poisson's ratio originates from the interplay of lattice symmetry and Si-O tetrahedron symmetry. Slab silica is also an insulating 2D material, with the highest electronic band gap (> 7 eV) among reported 2D structures. These exotic 2D silica with in-plane negative Poisson's ratios and widest band gaps are expected to have great potential applications in nanomechanics and nanoelectronics.