Gallium nanoparticles (Ga NPs) are attracting increasing attention because of their appealing physical-chemical properties. In particular, their mechanical properties play a key role in the implementation of these core-shell structures on certain applications, such as soft and stretchable electronics. Thus, efforts are being addressed to modulate them mainly by chemical means. In contrast, this study investigates how the mechanical properties of the outer gallium thin oxide shell change when its thickness is increased through a thermal oxidation strategy. Specifically, as-deposited Ga NPs, as well as those subjected to thermal oxidation at 300 °C for three different times, are studied by performing single-particle indentations by atomic force microscopy over a wide range of NP radius. This analysis helps to confirm that the Reissner's thin-shell model for small deformations within the elastic regime is obeyed. From these data, the dependence of the shell stiffness and the Young's modulus of the gallium oxide on the thermal treatment is obtained. It is found that the shell stiffness increases with the annealing time, even by a factor of 50 under prolonged thermal oxidation, while the gallium oxide Young's modulus, close to 30 GPa, does not change significantly.

中文翻译：

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低温热氧化对核壳液态镓纳米粒子力学性能的改性

镓纳米颗粒（Ga NPs）因其吸引人的物理化学性质而越来越受到关注。特别是，它们的机械性能在某些应用（例如柔软和可拉伸的电子产品）中实现这些核壳结构中起着关键作用。因此，正在努力主要通过化学手段来调节它们。相比之下，本研究调查了当通过热氧化策略增加厚度时，外层镓薄氧化物壳的机械性能如何变化。具体而言，通过原子力显微镜在很宽的 NP 半径范围内进行单粒子压痕，研究了沉积的 Ga NPs，以及那些在 300 °C 下热氧化三个不同时间的纳米粒子。该分析有助于确认 Reissner 的 遵循弹性范围内小变形的薄壳模型。从这些数据中，可以获得壳刚度和氧化镓的杨氏模量对热处理的依赖性。发现壳刚度随退火时间增加，甚至在长时间热氧化下增加 50 倍，而接近 30 GPa 的氧化镓杨氏模量没有显着变化。