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首页> 外文期刊>Crystal growth & design >Mechanical anisotropy in crystalline saccharin: Nanoindentation studies
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Mechanical anisotropy in crystalline saccharin: Nanoindentation studies

机译：结晶糖精的机械各向异性：纳米压痕研究

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The nanoindentation technique has been employed to relate the mechanical properties of saccharin single crystals with their internal structure. Indentations were performed on (100) and (011) faces to assess the mechanical anisotropy. The load-displacement (P-h) curves indicate significant differences in the nature of the plastic deformation on the two faces. The P-h curves obtained on the (011) plane are smooth, reflecting homogeneous plasticity. However, displacement bursts (pop-ins) are observed in the P-h curves obtained on the (100) plane suggesting a discrete deformation mechanism. Marginal differences exist in the hardness and modulus on the two faces that may, in part, be rationalized, although one notes that saccharin has a largely three-dimensional close-packed structure. The structural origins of the fundamentally different deformation mechanisms on (100) and (011) are discussed in terms of the dimensionality of the hydrogen bonding networks. Down the (100) planes, the saccharin dimers are stacked and are stabilized by nonspecific van der Waals interactions mostly between aromatic rings. However, down the (011) planes, the molecules are stabilized by more directional and cross-linked C-H?O hydrogen bonds. This anisotropy in crystal packing and interactions is reflected in the mechanical behavior on these faces. The displacements associated with the pop-ins were found to be integral multiples of the molecule separation distances. Nanoindentatixon offers an opportunity to compare experimentally, and in a quantitative way, the various intermolecular interactions that are present in a molecular crystal.
机译：纳米压痕技术已被用来将糖精单晶的机械性能与其内部结构联系起来。在（100）和（011）面上进行压痕以评估机械各向异性。载荷-位移（P-h）曲线表明两个面上塑性变形的性质存在显着差异。在（011）平面上获得的P-h曲线是平滑的，反映了均匀的可塑性。但是，在（100）平面上获得的P-h曲线中观察到位移爆裂（弹入），表明存在离散的变形机制。尽管有人指出糖精在很大程度上是三维密排结构，但在两个面上的硬度和模量存在边际差异，这可以部分地合理化。根据氢键网络的尺寸，讨论了（100）和（011）上根本不同的变形机制的结构起源。在（100）平面上，糖精二聚体堆叠并通过主要在芳环之间的非特异性范德华相互作用来稳定。但是，在（011）平面上，分子被更多的方向性和交联的C-H2O氢键所稳定。晶体堆积和相互作用中的这种各向异性反映在这些面上的机械行为中。发现与弹出物相关的位移是分子分离距离的整数倍。 Nanoindentatixon提供了一个机会，可以进行实验性比较，并以定量方式比较分子晶体中存在的各种分子间相互作用。

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