Molecular dynamics simulations of the tensile of ice nanowires
In recent years,human activities in sea ice-covered regions have frequently confronted serious challenges with the development of marine transportation,polar exploration,and other related fields.Therefore,the structural and mechanical properties of ice have become increasingly important.Under external forces,bulk ice(characterized by macroscopic dimensions in all three directions)typically exhibits brittle fracture,and experiments have demonstrated that its maximum strain rarely exceeds 0.3％(ranging from 100 to 260 K).However,in 2021,Xu and colleagues successfully synthesized one-dimensional single-crystal ice nanowires with diameters in the nanometer range and a near-perfect internal structure.Based on bending tests,they observed an impressive elastic strain of approximately 11％,which approaches the theoretical limit for ice(ranging from 14％to 17％).Furthermore,these nanowires possess a uniform surface with minimal waveguide loss,presenting potential applications in optical signal transmission and sensing.Nonetheless,despite their promising potential,research on these novel ice nanowires remains limited.Accurate characterization of their nanoscale microstructures poses a challenge for experimental techniques,leaving uncertainties in understanding their microscopic structure and mechanical behavior during tensile deformation.To bridge this gap,we employed molecular dynamics simulations,which can provide atomic and molecular-level insights into system structures and properties,to investigate the mechanical properties of ice nanowires under tensile loading.In this study,we specifically simulated an ice nanowire with a radius of 3 nm at 150 K.Our findings revealed a linear relationship between stress and strain in the initial stage,with an elastic limit and maximum elastic strain of 0.93 GPa and 10.32％,respectively.Upon further straining,the nanowire fractured,accompanied by significant lattice melting in the fracture region,resulting in distinct hydrogen bonding changes as compared to the non-fractured zone.Moreover,our simulations indicated that the mechanical properties of ice nanowires,including elastic limit,maximum elastic strain,Young's modulus,and Poisson's ratio,all decrease with increasing temperature.Compared to bulk ice,ice nanowires are more sensitive to temperature changes.This is because there is a melting layer at the edges of ice nanowires.As the temperature rises,the number of melting water molecules at the edges increases,further reducing the mechanical properties of the ice nanowires.Additionally,as the strain rate increases,the elastic limit and maximum elastic strain increase.Furthermore,we found distinct failure modes for nanowires with different orientations,with the[0001]orientation exhibiting the strongest mechanical performance.As microfibers,ice nanowires can find applications in optical sensing.For practical use,their properties may be affected by applying tensile loads.This work significantly expands the understanding of the structural and mechanical properties of ices,particularly ice nanowires.Moreover,the present findings provide a solid theoretical foundation for further exploration and application of ice nanowires,paving the way for their potential utilization in various fields.
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