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

Abstract

We propose three-dimensional carbon (3D-C) structures based on the Archimedean lattices (ALs) by combining sp 2 bonding in the polygon edges and sp 3 bonding in the polygon vertices. By first-principles calculations, four types of 3D-C ALs: (4, 8 2 ), (3, 12 2 ), (6 3 ), and (4 4 ) 3D-Cs are predicted to be stable both dynamically and mechanically among 11 possible ALs, in which the notations (p 1 , p 2 , . . .) are the indices of the AL structures. Depending on their indices, the 3D-C ALs show distinctive electronic properties: the (4, 8 2 ) 3D-C is an indirect band-gap semiconductor, the (3, 12 2 ) 3D-C is semimetal, while the (6 3 ) and (4 4 ) 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, 8 2 ) and (3, 12 2 ) 3D-Cs as a function of charge doping, respectively. Moreover, the (3, 12 2 ) 3D-C exhibits a sp 2 -sp 3 phase transformation at high charge doping, which leads to a huge 30% irreversible strain, while the reversible strain in the (4, 8 2 ) 3D-C is up to 9%, and thus they are quite promising for electromechanical actuators.

Two-dimensional MoS2 electromechanical actuators

“…For the hole doping (q > 0 e/atom), Y of 1T structure is increased, while Y of the 1H and 1T structures decreased. The maximum Y of monolayer MoS 2 of about 200 GPa is smaller than that of carbon-based structures (400 − 1000 GPa) [3,34], but is comparable to that of stainless steel (192 GPa) [35]. The high Y values of monolayer MoS 2 are important for artificial muscle applications since it could generate large force per unit area.…”

Charge-induced electromechanical actuation of Mo- and W-dichalcogenide monolayers

“…The electron (hole) doping is simulated by adding (removing) electrons to the unit cell with a uniform charge background. 25,26 The elastic constants C ij of MX 2 monolayers are estimated by using the Themo-pw code. 27 Since the values of C ij are related to the equivalent volume of the unit cell, the calculated C ij must be rescaled by h/d 0 , where h is the length of the cell along z axis and d 0 is the effective layer thickness of the MX 2 monolayers (d 0 ¼ 6.145Å).…”

Charge-induced high-performance actuation of borophene

“…To investigate the actuator properties of borophene, we perform the optimized structure for each charge doping q, in which q is in the range of −0.04 to +0.04 e/atom. For electron or hole dopings, the electrons are added or removed to the system, respectively, with a uniform background of charge [7,28]. To determine the ideal strength σ i (i.e.…”