Related papers: Lonsdaleite: The diamond with optimized bond lengt…
Hexagonal diamond has been predicted computationally to display extraordinary physical properties including a hardness that exceeds cubic diamond. However, a recent electron microscopy study has shown that so-called hexagonal diamond…
Hexagonal diamond (h-diamond), or Lonsdaleite, has been reported to be a wide-bandgap semiconductor with high thermal conductivity and hardness. Our \textit{ab initio} calculations reveal its exceptionally high carrier mobility at room…
Graphite and diamond are two well-known allotropes of carbon with distinct physical properties due to different atomic connectivity. Graphite has a layered structure in which the honeycomb carbon sheets can easily glide, while atoms in…
In a recent Letter, Fujii et. al. [Phys. Rev. Lett. 125, 016001] predicted a new carbon allotrope, pentadiamond, with remarkable mechanical properties: elastic moduli comparable or larger than diamond, and negative Poisson's ratio $\mu$ =…
We explore the structural evolution of highly oriented pyrolytic graphite (HOPG) under detonation-induced shock conditions using in-situ synchrotron X-ray diffraction in the ns time scale. We observe the formation of hexagonal diamond…
Hexagonal diamond, often called lonsdaleite, is an exotic allotrope of carbon, predicted to be harder than cubic (conventional) diamond with a wider bandgap. Due to its pure sp$^3$ bonded lattice, it should be expected to host sub-bandgap…
We introduce a computational approach to estimate the hardness and stiffness of diamond surfaces and nanoparticles by studying their elastic response to atomic nanoindentation. Results of our ab initio density functional calculations…
A new ultra-hard rhombohedral carbon rh-C4 (or hexagonal h-C12) is reported as derived from 3R graphite through crystal chemistry construction and ground state energy within the density functional theory. An extended hexagonal…
Carbon is likely the most fascinating element of the periodic table because of the diversity of its allotropes stemming from its variable (sp, sp2, and sp3) bonding motifs. Exploration of new forms of carbon has been an eternal theme of…
Based on crystal chemistry considerations and quantum density functional theory ground state calculations, rhombohedral rh-C3 and hexagonal h-C6 carbon allotropes are proposed and energetically calculated as new stable ultra-hard phases…
Most of hydrocarbons are either molecular structures or linear polymeric chains. Discovery of graphene and manufacturing of its monohydride -- graphane incite interest in search for three-dimensional hydrocarbon polymers. However up to now…
Nearly two-dimensional diamond, or diamane, is coveted as ultrathin $sp^3$-carbon film with unique mechanics and electro-optics. The very thinness ($~h$) makes it possible for the surface chemistry, e.g. adsorbed atoms, to shift the bulk…
Through a systematic structural search we found an allotrope of carbon with Cmmm symmetry which we predict to be more stable than graphite for pressures above 10 GPa. This material, which we refer to as Z-carbon, is formed by pure sp3 bonds…
Enhancing the fracture toughness of diamond while preserving its hardness is a significant challenge. Traditional toughening strategies have primarily focused on modulating the internal microstructural units of diamonds, including…
The lon topology inherent to lonsdaleite C4 hexagonal diamond is shown to characterize three original carbon allotropes C8 in the orthorhombic system with irregular orientations of the C4 tetrahedra. The octacarbon stoichiometries were…
The shock strength dependent formation of diamond represents one of the most intriguing questions in graphite research. Using ab initio DFT-trained carbon GNN model, we observe a strength-dependent graphite transition under shock. The poor…
The electronic structure and dielectric properties of the diamond, body centered cubic diamond (bc8), and hexagonal diamond (lonsdaleite) phases of carbon are computed using density functional theory and many-body perturbation theory with…
Atomically thin graphite, known as graphene, has been a marvel in material science because of its exceptional properties, novel physics and promising applications. Atomically thin diamond, called diamane, has also attracted considerable…
Diamond possesses exceptional physical properties due to its remarkably strong carbon-carbon bonding, leading to significant resilience to structural transformations at very high pressures and temperatures. Despite several experimental…
The formation of technologically valuable nanocarbon structures under extreme conditions, such as those produced during high-explosive detonations, remains poorly understood but holds significant potential for the development of controlled…