Mechanical twinning changes atomic, molecular, and crystal orientations along with directions of the anisotropic properties of the crystalline materials while maintaining single crystallinity in each domain. However, such deformability has been less studied in brittle organic crystals despite their remarkable anisotropic functions. Herein we demonstrate a direction-dependent mechanical twinning that shows superelasticity in one direction and ferroelasticity in two other directions in a single crystal of 1,3-bis(4-methoxyphenyl)urea. The crystal can undergo stepwise twinning and ferroelastically forms various shapes with multiple domains oriented in different directions, thereby affording a crystal that shows superelasticity in multiple directions. This adaptability and shape recoverability in a ferroelastic and superelastic single crystal under ambient conditions are of great importance in future applications of organic crystals as mechanical materials, such as in soft robotics.

中文翻译：

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多功能铁弹性操纵的多向超弹性有机晶体。

机械孪晶会改变原子，分子和晶体的取向，以及晶体材料的各向异性特性的方向，同时在每个域中都保持单一结晶度。然而，尽管它们具有显着的各向异性功能，但在脆性有机晶体中却很少研究这种可变形性。本文中，我们展示了一种方向相关的机械孪晶，该孪晶在1，3-双（4-甲氧基苯基）脲单晶中显示了一个方向的超弹性和两个方向的铁弹性。晶体可以进行逐步孪晶，并且铁弹性地形成具有在不同方向上取向的多个畴的各种形状，从而提供了在多个方向上显示超弹性的晶体。