Elastic-plastic transition at nanoindentation of (111) plane of pure C60 fullerite single crystals was studied. The onset of plastic deformation in the contact was noted due to the plateau formation in the initial part of loading curve. The estimated stress of plasticity beginning was found to be on the order of the theoretical shear stress required for homogeneous dislocation nucleation in the ideal crystal lattice of C60. The empirical values of elastic modulus E ∼ 13.5 GPa, hardness of the ideal crystal lattice H ∼ 1.4 GPa, and hardness at different indentation loads were obtained. The hardness vs load dependence was found consistent with the model of geometrically necessary dislocations. The loading diagrams shape and the dependencies of contact pressure vs indentation depth were strongly affected by gaseous interstitial impurities (hydrogen, oxygen, nitrogen) in C60 crystal; transition stress was essentially less and plateaus formation was observed at elevated indentation loads and depths as compared with pure fullerite crystal. For crystals, saturated with hydrogen, the enhanced value of elastic modulus (∼ 20.4 GPa) and hardness (∼ 1.1 GPa) were obtained. The results acquired at room temperature for C60 with face-centered cubic lattice are important for the description of the physical-mechanical properties of simple cubic lattice phase of C60 below 260 K (S. V. Lubenets, L. S. Fomenko, V. D. Natsik, and A. V. Rusakova, Fiz. Nizk. Temp. 45, 3 (2019) [Low Temp. Phys. 45, 1 (2019)]).

中文翻译：

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纯和气体饱和富勒体 C60 晶体的纳米压痕：弹塑性转变、硬度、弹性模量

研究了纯 C60 富勒体单晶 (111) 面纳米压痕处的弹塑性转变。由于在加载曲线的初始部分形成了平台，因此注意到接触中塑性变形的开始。发现塑性开始的估计应力与在 C60 的理想晶格中均匀位错成核所需的理论剪切应力相当。得到了弹性模量E ∼ 13.5 GPa、理想晶格硬度H ∼ 1.4 GPa、不同压痕载荷下硬度的经验值。发现硬度对载荷的依赖性与几何必要位错模型一致。加载图的形状和接触压力与压痕深度的相关性受气态间隙杂质（氢、C60晶体中的氧、氮）；与纯富勒体晶体相比，过渡应力基本上较小，并且在压痕载荷和深度升高时观察到平台形成。对于被氢饱和的晶体，弹性模量（~20.4 GPa）和硬度（~1.1 GPa）的增强值被获得。具有面心立方晶格的 C60 在室温下获得的结果对于描述低于 260 K 的 C60 简单立方晶格相的物理机械特性很重要（SV Lubenets、LS Fomenko、VD Natsik 和 AV Rusakova，Fiz . Nizk. Temp. 45, 3 (2019) [Low Temp. Phys. 45, 1 (2019)])。用氢饱和，获得了弹性模量（〜20.4 GPa）和硬度（〜1.1 GPa）的增强值。具有面心立方晶格的 C60 在室温下获得的结果对于描述低于 260 K 的 C60 简单立方晶格相的物理机械特性很重要（SV Lubenets、LS Fomenko、VD Natsik 和 AV Rusakova，Fiz . Nizk. Temp. 45, 3 (2019) [Low Temp. Phys. 45, 1 (2019)])。用氢饱和，获得了弹性模量（〜20.4 GPa）和硬度（〜1.1 GPa）的增强值。具有面心立方晶格的 C60 在室温下获得的结果对于描述低于 260 K 的 C60 简单立方晶格相的物理机械特性很重要（SV Lubenets、LS Fomenko、VD Natsik 和 AV Rusakova，Fiz . Nizk. Temp. 45, 3 (2019) [Low Temp. Phys. 45, 1 (2019)])。3 (2019) [低温。物理。45, 1 (2019)])。3 (2019) [低温。物理。45, 1 (2019)])。