Negative and positive anisotropic thermal expansion in 2D fullerene networks

Armaan Shaikh; Jiaqi Wu; Bo Peng

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arXiv · 2504.02037

Negative and positive anisotropic thermal expansion in 2D fullerene networks

Armaan Shaikh·Jiaqi Wu·Bo Peng

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Abstract

We find a design principle for tailoring thermal expansion properties in nearly-spherical molecular networks. Using 2D fullerene networks as a representative system, we realize positive thermal expansion along intermolecular [2\,+\,2] cycloaddition bonds and negative thermal expansion along intermolecular C$-$C single bonds by varying the structural frameworks of molecules. The microscopic mechanism originates from a combination of the framework's geometric flexibility and its transverse vibrational characteristics. Based on this insight, we find molecular networks beyond C$_{60}$ with tunable thermal expansion. These findings shed light on the fundamental mechanisms governing thermal expansion in molecular networks towards rational materials design.

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Armaan Shaikh, Jiaqi Wu, Bo Peng. 2025-04-02. Negative and positive anisotropic thermal expansion in 2D fullerene networks. https://arxiv.org/abs/2504.02037

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