Schwarzites are 3D crystalline porous materials exhibiting the shape of Triply Periodic Minimal Surfaces (TPMS). They possess negative Gaussian curvature, created by the presence of rings with more than six sp2-hybridized carbon atoms. Recently, new routes to their synthesis have been proposed. Due to its foam-like structure, schwarzites are interesting for mechanical energy absorption applications. In this work, we investigate through fully atomistic reactive molecular dynamics the mechanical response under ballistic impacts of four structures from primitive (P) and gyroid (G) families (two structures within each family). The two structures in the same family differ mainly by the ratio of hexagons to octagons, where this ratio increases the 'flatness' of the structures. Although the penetration depth values are higher in the 'flatter' structures (P8bal and G8bal), the absorbed kinetic energy by them is considerably higher, which yields them a better energy-absorption performance.
Since graphene was synthesized the interest for building new 2D and 3D structures based on the carbon allotropes has been growing every day. One of these 3D structures is know as carbon schwarzites. Schwarzites consist of carbon nanostructures possessing the shape of Triply-Periodic Minimal Surfaces (TPMS), which is characterized by a negative Gaussian curvature introduced by the presence of carbon rings with more than six atoms. Some examples of schwarzite families include: primitive (P), gyroid (G) and diamond (D). Previous studies considering different element species of schwarzites have in…
Schwarzites are porous structures that present negative Gaussian curvatures. Although initially proposed for carbon, in principle, schwarzites of other elements are possible. In this work, we have carried out a detailed investigation of the effect of element composition (C, Ge, Si, SiC, and BN) on the structural, electronic and optical properties of a gyroid schwarzite structure, the so-called G688. The DFT simulations were carried out using the well-known SIESTA code. Our results showed that formation energy values are in similar range of other related allotrope structures and are thermally s…
We investigated through fully atomistic molecular dynamics simulations, the mechanical behavior (compressive and tensile) and energy absorption properties of two families (primitive (P688 and P8bal) and gyroid (G688 and G8bal)) of carbon-based schwarzites. Our results show that all schwarzites can be compressed (with almost total elastic recovery) without fracture to more than 50%, one of them can be even remarkably compressed up to 80%. One of the structures (G8bal) presents negative Poisson's ratio value (auxetic behavior). The crush force efficiency, the stroke efficiency and the specific e…
Nature-occurring structures exhibiting unique topological features such as complex and gradient porosity has been the basis to create new materials and/or structures. Most studies have been focused on complex periodic porous structures but gradient porous ones have not been yet fully investigated for stable structural designs. In this work, we have proposed and tested a new approach to create cellular griding structures, in which the mass density varies from the center to the borders, i.e, a radial gradient. To create these new structures we exploited the topology of two carbon-based families …
The 3D porous carbon-based structures called Schwarzites have been recently a subject of renewed interest due to the possibility of being synthesized in the near future. These structures exhibit negatively curvature topologies with tuneable porous sizes and shapes, which make them natural candidates for applications such as CO2 capture, gas storage and separation. Nevertheless, the adsorption properties of these materials have not been fully investigated. Following this motivation, we have carried out Grand-Canonical Monte Carlo simulations to study the adsorption of small molecules such as CO…
Triply Periodic Minimal Surfaces (TPMS) possess locally minimized surface area under the constraint of periodic boundary conditions. Different families of surfaces were obtained with different topologies satisfying such conditions. Examples of such families include Primitive (P), Gyroid (G) and Diamond (D) surfaces. From a purely mathematical subject, TPMS have been recently found in materials science as optimal geometries for structural applications. Proposed by Mackay and Terrones in 1991, schwarzites are 3D crystalline porous carbon nanocrystals exhibiting the shape of TPMS. Although their …
We will study the competitive effect between the transport of a quantum dot adsorbed to a ballistic channel and laterally coupled to a single-walled carbon nanotube (SWNT). We will use the tight-binding approach to analytically write the SWNT Green function and the quantum dot will be solved by the atomic method for U very large. We will present curves of the electronic density of states for some different sizes of nanotubes. The results for the conductance curves will be presented as a function of Ef and for different values of n and hopping between the nanotube and the quantum dot.
Carbon nanostructures are promising ballistic protection materials, due to their low density and excellent mechanical properties. Recent experimental and computational investigations on the behavior of graphene under impact conditions revealed exceptional energy absorption properties as well. However, the reported numerical and experimental values differ by an order of magnitude. In this work, we combined numerical and analytical modeling to address this issue. In the numerical part, we employed reactive molecular dynamics to carry out ballistic tests on single and double-layered graphene shee…
