Single crystals of aspirin form I were cleaved and indented on their dominant face. Upon inspection, it was possible to observe strongly anisotropic shallow lateral cracks due to the extreme low surface roughness after cleavage. Atomic force microscopy (AFM) imaging showed spalling fractures nucleating from the indent corners, forming terraces with a height of one or two interplanar spacings d₁₀₀. The formation of such spalling fractures in aspirin was rationalized using basic calculations of attachment energies, showing how (100) layers are poorly bonded when compared to their relatively higher intralayer bonding. An attempt at explaining the preferential propagation of these fractures along the [010] direction is discussed.

中文翻译：

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阿司匹林晶体的脆性行为：剥落性断裂的证据

阿司匹林晶型I的单晶被切割并在其主导面上凹陷。经检查，由于解理后的极低表面粗糙度，可以观察到强烈的各向异性浅横向裂缝。原子力显微镜（AFM）成像显示从压痕角成核的剥落性骨折，形成高度为一或两个晶面间距d _100的阶地。使用附着能的基本计算合理化了阿司匹林中此类剥落性骨折的形成，表明与相对较高的层内粘结相比，（100）层的粘结性较差。讨论了试图解释这些裂缝沿[010]方向优先传播的尝试。