arXiv subjects

Emanuel J. A. dos Santos

Publications and source records attributed to Emanuel J. A. dos Santos.

4 recordsLinked to original sources

arXiv2026

Multiscale Mechanical Response of 3D-Printed Diamondiynes: From Movable Interlocked Lattices to Architected Metamaterials

Diamondynes are a recently synthesized three-dimensional carbon allotrope, with interlocked and movable sublattices that introduce deformation modes not present in standard architected materials. Here, we report the first multiscale mechanical assessment of Diamondiyne-derived architectures by combining quasi-static compression of 3D-printed specimens with reactive molecular dynamics simulations of the corresponding atomic-scale models. We generate four geometries (3F, 2F-SY, 4F, and 2F-USY). All structures resulted in lower density in the range of 0.20-0.38 g.cm^-3. Experiments indicate that the symmetric two-sublattice structure (2F-SY) delivers the best performance, reaching a specific yield strength of 5.91 MPa.g^-1cm^-3 and a specific energy absorption of 279 J.g^-1, whereas 2F-USY architecture yielded the lowest values, with 0.77 MPa.g^-1.cm^-3 and 16 J.g^-1. The 4F geometry provided a specific energy absorption of 254 J.g^-1. The structures deformed through geometric collapse and strut buckling, which was due to diagonal shear in 2F-USY and progressive compaction in 2F-SY and 3F. Molecular dynamics simulations also confirmed these experimental trends and revealed strong directional anisotropy due to the arrangement of interlocked sublattices, with a stiffness of 24.1 GPa along the z-direction in the case of 4F architecture. Overall, Diamondiyne-derived architectures display geometry-dominated mechanical behavior and serve as a promising platform for lightweight, energy-absorbing metamaterials.

physics.app-ph↗

arXiv2025

Kagome Topology in Two-Dimensional Noble-Metal Monolayers

Two-dimensional (2D) metallic lattices with kagome topology provide a unique platform for exploring the interplay between geometric frustration, reduced coordination, and lattice stability in elemental systems. Motivated by the recent experimental realization of atomically thin gold layers and kagome goldene, we present a first-principles investigation of free-standing kagome monolayers of Cu, Ag, and Au. Using density functional theory combined with lattice dynamics and ab initio molecular dynamics, we systematically assess their structural, mechanical, dynamical, and thermal stability. All kagome monolayers satisfy the 2D Born criteria and exhibit relatively low in-plane stiffness compared to graphene and hexagonal goldene, reflecting the porous nature of the kagome lattice and its metallic bonding. Among the three systems, the Au-based lattice displays the highest in-plane Young's modulus. Phonon calculations reveal that the unstrained kagome phase is dynamically unstable for all metals. However, a moderate biaxial tensile strain of 5% stabilizes the Ag and Au monolayers, while Cu retains residual unstable modes. Finite-temperature simulations further show that Cu rapidly reconstructs toward a trigonal lattice, Ag remains metastable at low temperature but collapses at room temperature, and Au exhibits competing kagome and trigonal motifs at 300 K, indicating near-degeneracy between these phases. These results establish that strain engineering and atomic size are key determinants of the stability of metallic kagome monolayers and provide guidance for future substrate-supported realizations.

cond-mat.mtrl-sci↗

arXiv2025

Exploring Novel 2D Analogues of Goldene: Electronic, Mechanical, and Optical Properties of Silverene and Copperene

Two-dimensional (2D) materials have garnered significant attention due to their unique properties and broad application potential. Building on the success of goldene, a monolayer lattice of gold atoms, we explore its proposed silver and copper analogs, silverene and copperene, using density functional theory calculations. Our findings reveal that silverene and copperene are energetically stable, with formation energies of -2.3 eV/atom and -3.1 eV/atom, closely matching goldene's -2.9 eV/atom. Phonon dispersion and ab initio molecular dynamics simulations confirm their structural and dynamical stability at room temperature, showing no bond breaking or structural reconfiguration. Mechanical analyses indicate isotropy, with Young's moduli of 73 N/m, 44 N/m, and 59 N/m for goldene, silverene, and copperene, respectively, alongside Poisson's ratios of 0.46, 0.42, and 0.41. These results suggest comparable rigidity and deformation characteristics. Electronic band structure analysis highlights their metallic nature, with variations in the band profiles at negative energy levels. Despite their metallic character, these materials exhibit optical properties akin to semiconductors, pointing to potential applications in optoelectronics.

cond-mat.mtrl-sci↗

arXiv2024

How does Goldene Stack?

The recent synthesis of Goldene, a 2D atomic monolayer of gold, has opened new avenues in exploring novel materials. However, the question of when multilayer Goldene transitions into bulk gold remains unresolved. This study used density functional theory calculations to address this fundamental question. Our findings reveal that multilayer Goldene retains an AA-like stacking configuration of up to six layers, with no observation of Bernal-like stacking as seen in graphene. Goldene spontaneously transitions to a bulk-like gold structure at seven layers, adopting a rhombohedral (ABC-like) stacking characteristic of bulk face-centered cubic (FCC) gold. The atomic arrangement converges entirely to the bulk gold lattice for more than ten layers. Quantum confinement significantly impacts the electronic properties, with monolayer and bulk Goldene exhibiting a single Dirac cone at the X-point of the Brillouin zone. In contrast, multilayer Goldene shows two Dirac cones at the X- and Y-points. Additionally, monolayer Goldene exhibits anisotropic optical absorption, which is absent in bulk gold. This study provides a deeper understanding of multilayer Goldene's structural and electronic properties and stacked 2D materials in general.

cond-mat.mtrl-sci↗