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Abstract <p>This study presents a comprehensive molecular dynamics investigation of the mechanical behavior of BN twin-4-8-graphene, a novel two-dimensional nanomaterial characterized by its unique 4–8 ring lattice architecture. The research systematically examines the influence of critical design parameters—including nanosheet dimensions, operating temperature, structural defects, and layer configuration—on fundamental mechanical properties such as elastic modulus, ultimate tensile strength, and fracture toughness. The material demonstrates pronounced mechanical anisotropy, with vertical loading orientation exhibiting approximately 10.5% greater strain tolerance compared to horizontal loading, attributed to preferential stress distribution pathways within the asymmetric lattice structure. Strong size-dependent mechanical behavior is observed, where increasing lateral dimensions from 50 to 150&#xa0;Å results in elastic modulus reductions of up to 16.7% and ultimate strength decreases exceeding 40%, primarily due to diminishing surface and edge effects. Elevated temperatures induce severe mechanical degradation through thermal softening, with property reductions of 46.5% in elastic modulus, over 70% in ultimate stress, and 83% in toughness at 1000&#xa0;K compared to low-temperature performance. Vacancy defects act as critical stress concentrators, causing catastrophic mechanical deterioration even at modest concentrations (3%), with ultimate stress reductions of 74% and toughness decreases of 84%. The defect-induced mechanical anisotropy reveals preferential degradation along specific crystallographic directions, with the x-direction showing enhanced sensitivity to vacancy concentration. Conversely, multilayer configurations demonstrate mechanical enhancement, particularly in strength and toughness parameters, despite slight elastic modulus reductions due to weak interlayer interactions. Fracture analysis reveals a brittle failure mechanism with crack propagation following preferential paths through geometric stress concentrators, particularly eight-membered ring structures. These comprehensive findings provide essential design guidelines for optimizing BN twin-4-8-graphene integration into advanced applications including flexible electronics, high-performance nanocomposites, strain-engineered devices, and nanoscale mechanical systems, while highlighting critical considerations for thermal management and defect control in practical implementations.</p> Graphical Abstract <p></p>

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Tuning Brittle Fracture in Anisotropic BN Twin-4-8-Graphene: Effects of Layer Number, Defects, and Temperature

  • 期刊论文

  • 发表日期：

    2025年11月18日

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  • Zhuyong Su,
  • Wuchen Shi,
  • Ali Ghasemi

摘要

Abstract

This study presents a comprehensive molecular dynamics investigation of the mechanical behavior of BN twin-4-8-graphene, a novel two-dimensional nanomaterial characterized by its unique 4–8 ring lattice architecture. The research systematically examines the influence of critical design parameters—including nanosheet dimensions, operating temperature, structural defects, and layer configuration—on fundamental mechanical properties such as elastic modulus, ultimate tensile strength, and fracture toughness. The material demonstrates pronounced mechanical anisotropy, with vertical loading orientation exhibiting approximately 10.5% greater strain tolerance compared to horizontal loading, attributed to preferential stress distribution pathways within the asymmetric lattice structure. Strong size-dependent mechanical behavior is observed, where increasing lateral dimensions from 50 to 150 Å results in elastic modulus reductions of up to 16.7% and ultimate strength decreases exceeding 40%, primarily due to diminishing surface and edge effects. Elevated temperatures induce severe mechanical degradation through thermal softening, with property reductions of 46.5% in elastic modulus, over 70% in ultimate stress, and 83% in toughness at 1000 K compared to low-temperature performance. Vacancy defects act as critical stress concentrators, causing catastrophic mechanical deterioration even at modest concentrations (3%), with ultimate stress reductions of 74% and toughness decreases of 84%. The defect-induced mechanical anisotropy reveals preferential degradation along specific crystallographic directions, with the x-direction showing enhanced sensitivity to vacancy concentration. Conversely, multilayer configurations demonstrate mechanical enhancement, particularly in strength and toughness parameters, despite slight elastic modulus reductions due to weak interlayer interactions. Fracture analysis reveals a brittle failure mechanism with crack propagation following preferential paths through geometric stress concentrators, particularly eight-membered ring structures. These comprehensive findings provide essential design guidelines for optimizing BN twin-4-8-graphene integration into advanced applications including flexible electronics, high-performance nanocomposites, strain-engineered devices, and nanoscale mechanical systems, while highlighting critical considerations for thermal management and defect control in practical implementations.

Graphical Abstract