Related papers: Symmetry-broken crystal structure of elemental bor…
Recent discoveries of supposedly pure alpha-tetragonal boron require to revisit its structure. The system is also interesting with respect to a new type of geometrical frustration in elemental crystals, which was found in beta-rhombohedral…
The assessed phase diagram of the boron-carbon system contains a single non-stoichiometric boron-carbide phase of rhombohedral symmetry with a broad, thermodynamically improbable, low temperature composition range. We combine first…
Boron is an element of fascinating chemical complexity. Controversies have shrouded this element since its discovery was announced in 1808: the new 'element' turned out to be a compound containing less than 60-70 percent of boron, and it…
Boron is a unique element, being the only element, all known polymorphs of which are superhard, and all of its crystal structures are distinct from any other element. The electron-deficient bonding in boron explains its remarkable…
Elementary semiconductors are rare and attractive, especially for low-dimensional materials. Unfortunately, most of boron nanostructures were found to be metallic, despite of their typical semiconducting bulk structure. Herein, we propose a…
The recent discovery of borophene, a two-dimensional allotrope of boron, raises many questions about its structure and its chemical and physical properties. Boron has a high chemical affinity to oxygen but little is known about the…
The structures, stability, mechanical and electronic properties of a-boron and its twined brother a*-boron have been studied by first-principles calculations. Both a-boron and a*-boron consist of equivalent icosahedra B12 clusters in…
Boron Carbide exhibits a broad composition range, implying a degree of intrinsic substitutional disorder. While the observed phase has rhombohedral symmetry (space group R3(bar)m), the enthalpy minimizing structure has lower, monoclinic,…
Molybdenum borides were studied theoretically using first-principles calculations, empirical total energy model and global optimization techniques to determine stable crystal structures. Our calculations reveal the structures of known Mo-B…
We present a structural analysis of the substituted system (Ba$_{1-x}$Sr$_{x}$)CuSi$_{2}$O$_{6}$, which reveals a stable tetragonal crystal structure down to 1.5 K. We explore the structural details with lowtemperature neutron and…
Ab initio random structure searching with density functional theory was used to determine the zero-temperature structures of atomic metallic hydrogen from 500 GPa to 5 TPa. Including zero point motion in the harmonic approximation, we…
The behavior of nuclear matter is studied at low densities and temperatures using classical molecular dynamics with three different sets of potentials with different compressibility. Nuclear matter is found to arrange in crystalline…
We prove a strong form of spontaneous breaking of rotational symmetry for a simple model of two-dimensional crystals with random defects in thermal equilibrium at low temperature. The defects consist of isolated missing atoms.
Properties of the $\omega$ structure are investigated for 27 transition elements from the viewpoints of thermodynamical and mechanical stability based on first-principles calculations. The thermodynamical stability of the $\omega$ structure…
Boron bulk crystals are marked by exceptional structural complexity and unusual related physical phenomena. Recent reports of hydrogenated $\alpha$-tetragonal and a new $\delta$-orthorhombic boron B$_{52}$ phase have raised many fundamental…
The crystal structure of barium-germanium clathrate Ba6Ge25 was studied using neutron powder diffraction in the temperature range 20-300K. The compound was found to be cubic (S.G. P4_1 23) in the entire temperature range. However, the…
Symmetry-breaking is pivotal for controlling ferroelectric, ferroelastic and/or ferromagnetic functions of materials, which enables applications in sensors, memories, transducers or actuators. Commonly, ferroic phases emerge from descending…
The elastic and magnetic properties, thermodynamical stability, deviation from stoichiometry and order/disorder transformations of phases that are relevant to Be alloys were investigated using density functional theory simulations coupled…
Mixtures of bare atomic nuclei on a nearly uniform degenerate electron background are a realistic model of matter in the interior of white dwarfs. Despite tremendous progress in understanding their phase diagrams achieved mainly via…
The results of electronic structure calculations for a variety of palladium hydrides are presented. The calculations are based on density functional theory and used different local and semilocal approximations. The thermodynamic stability…