Three-dimensional carbon Archimedean lattices for high-performance electromechanical actuators

We propose three-dimensional carbon (3D-C) structures based on the Archimedean lattices (ALs) by combining sp2 bonding in the polygon edges and sp3 bonding in the polygon vertices. By first-principles calculations, four types of 3D-C ALs: (4,82), (3,122), (63), and (44) 3D-Cs are predicted to be stable both dynamically and mechanically among 11 possible ALs, in which the notations (p1,p2,…) are the indices of the AL structures. Depending on their indices, the 3D-C ALs show distinctive electronic properties: the (4,82) 3D-C is an indirect band-gap semiconductor, the (3,122) 3D-C is semimetal, while the (63) and (44) 3D-Cs are metals. Considering the structural deformation due to the changes in their electronic energy bands, we discuss the electromechanical properties of the 3D-C ALs as a function of charge doping. We find a semiconductor-to-metal and semimetallic-to-semiconductor transitions in the (4,82) and (3,122) 3D-Cs as a function of charge doping, respectively. Moreover, the (3,122) 3D-C exhibits a sp2-sp3 phase transformation at high charge doping, which leads to a huge 30% irreversible strain, while the reversible strain in the (4,82) 3D-C is up to 9%, and thus they are quite promising for electromechanical actuators.

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