Increase In Number Of Atoms Research Articles

Theoretical investigation on Stark-induced transition probabilities of hydrogen-like ions

Based on the nondegenerate perturbation theory, the Stark-induced transitions are studied for hydrogen-like isoelectronic sequences (<i>Z</i> = 1–92). The Stark-induced mixing coefficients and transition probabilities between the 2s<sub>1/2</sub>-1s<sub>1/2</sub> levels of hydrogen-like ions are reported. The trend of Stark-induced transition probabilities varying with atomic number <i><i>Z</i></i> between 2s<sub>1/2</sub>-1s<sub>1/2</sub> levels of hydrogen-like ions and the relativistic effect on the Stark-induced mixing coefficients and transition probabilities are discussed. The scaling relations of the nonrelativistic and relativistic Stark-induced transition probabilities with atomic number <i>Z</i> are obtained. The results show that the Stark-induced transition probabilities of hydrogen-like ions decrease monotonically along the isoelectronic sequence with the increase of atomic number <i>Z</i>. In addition, the relativistic effect reduces the Stark-induced transition probabilities of hydrogen-like ions, for example, by about 55% at <i>Z</i> = 92.

Effects of atomic substitutional doping on electronic structure of monolayer Janus WSeTe

Based on the first principles calculations, the effects of substitutional doping of nitrogen, halogen and 3d transition metal elements on the electronic structure of monolayer Janus transition metal dichalcogenides WSeTe are studied in this paper, where the VASP software package is used based on density functional theory to perform calculations through using both the projector augmented wave method and the GGA-PBE functional method. A monolayer WSeTe hexagonal crystal system with 4 × 4 supercells is established, which contains 48 atoms. When VA (VIIA) element substitutes for monolayer WSeTe, one of the Se atoms is replaced with a nitrogen (halogen) atom; when the 3d transition metal element substitutes for monolayer WSeTe, one of the W atoms is replaced with a transition metal atom. Through the analysis of band structure, charge transfer and magnetism, it is found that VA (VIIA) nonmetallic elements doped monolayer WSeTe due to the introduction of the hole (electronic) doped, makes the Fermi level shift downward (upward), thus transforming into a p(n) type semiconductor. The Ti and V element substitutional doped monolayer WSeTe will present semiconductor-metal transformation. A doping for each of Cr, Co, Mn, Fe element doesn’t lead semiconductor material properties to change, but the each of Co, Mn, Fe element doped monolayer WSeTe can create a band gap of less than 20 meV. The VIIA (VA) non-metallic element and 3d transition metal element doped monolayer WSeTe will not have a huge influence on the original geometric structure of the material. Due to the charge transfer and doped atoms on the top of the valence band hybridization phenomenon, the Rashba spin splitting intensity near the <i>Γ</i> point of the top valence band increases with the increase of the atomic number of the doped atoms in the same main group when VIIA and VA non-metallic elements are doped. Moreover, the increase in atomic number and charge transfer have a greater influence on the strength of Rashba spin-orbit coupling than the change in electronegativity. The 3d transition metal element substitution doped single-layer WSeTe has obvious spin polarization phenomenon, which produces valley polarization near the Fermi level and introduces magnetism. In particular, since Cr-doped WSeTe retains the original semiconductor properties of WSeTe and has a large energy valley polarization, it may have a wide range of applications, such as in the field of spintronic devices. The monolayer WSeTe doped separately with Cr, Mn and Fe element produces an impurity band with fully polarized spin electrons in the band gap. The results are of great significance in systematically understanding the properties of monolayer WSeTe doping model and can provide theoretical reference for designing the monolayer WSeTe based electronic devices.

Theoretical characterization and application of mechanical behavior of atoms/ions migrating on graphene surface

The static and dynamic mechanical behaviors of atoms/ions migrating on graphene surface are investigated via theoretical and numerical calculations, and a design idea of nano-scale device that can be used for atoms/ions screening is proposed on this basis. By using the Fourier expansion of the interaction potential between atoms, the analytical expression of the interaction force between an atom/ion and infinitely large graphene is derived. The dependence of the interaction force on the vertical distance from the atom/ion to graphene surface and the atomic/ionic types are analyzed. Based on the interaction force, a dynamics governing equation for the migration of atoms/ions on graphene surface is established, and the dynamics behaviors of atoms/ions when they migrate on the graphene surface at different initial velocities are studied. Taking lithium-ion as an example, it is found that there are three migration states along the armchair direction of graphene. No matter which migration state, the lithium-ion will eventually be stably adsorbed above the center of a hexagonal carbon ring (the hollow site). By adjusting the initial velocity, the lithium-ion can be steadily adsorbed at the specified sites, so as to control the migration distance of lithium-ion. What's more, the functional relationship between the critical initial velocity of the lithium-ion and the stable adsorption sites on graphene surface is given, and the influence of the vertical distance from the lithium-ion to graphene surface on the migration process is analyzed. In addition, the dynamics behaviors of the migration of different atoms/ions on graphene surface are studied, and it is found that the migration of alkali metal particles is more free with the increase of atomic number, and the stable site is further away from the initial position, which is in good agreement with the results of molecular dynamics simulation in the literature. Besides, the effects of initial position, damping and migration path on the dynamics behaviors of atoms/ions migrating on graphene surface are also studied. Finally, on the basis of theoretical results, a design idea of graphene-based nano-scale device is proposed, which can be used to screen specified atoms/ions and control their in and out positions.

NUMERICAL SIMULATION OF DIFFERENT ATOMIC NUMBER IONS IRRADIATION EFFECTS ON BENZOCYLOBUTENE MATERIAL

In this paper, the irradiation effect of different atomic number incident ions on benzocylobutene(BCB) material was investigated by using the Monte Carlo method. The results indicated that the projected range of theof the ions got decreased and the irradiation damage region was moved closer to the surface with the increase of ion atomic number. However, the stopping power was increased with the increase of ion atomic number. Moreover, with the increase of the atomic number, particle distribution, ionization energy loss, vacancies and phonons are more in the irradiation damage zone, the radiation damage mechanism caused by the recoil atoms gradually dominates, and the influence caused by the incident particles is becoming secondary

The incompressibility of atoms at high pressures

Abstract The structures of the silica polymorphs α-quartz and stishovite have been geometry optimized at highly simulated isotropic pressure within the framework of Density Functional Theory. The atoms of the high-pressure polymorph stishovite are virtually incompressible with the bonded radii for Si and O atoms decreasing by only 0.04 and 0.08 Å, respectively, at 100 GPa. In compensating for the increase in the effective interatomic potential associated with the compression of the Si-O bonded interactions, the electron density at the bond critical point between the bonded pair increases from 0.69 to 0.89 e/Å 3. The bonded radii of the Si and O atoms for α-quartz decrease by 0.006 and 0.008 Å, respectively, between 1 bar and 26.4 GPa. The impact of simulated, isotropic pressure on the bonded radii of the atoms for three perovskites YAlO3, LaAlO3, and CaSnO3 was also examined at high pressure. For the YAlO3 perovskite, the bonded radii for Y and Al decrease by 0.06 and 0.05 Å, respectively, at 80 GPa, while the electron density between the bonded atoms increases by 0.12 and 0.15 e/Å3, on average. The calculations also show that the coordination number of the Y atom increases from 9 to 10 while the coordination number of the O1 atom increases concomitantly in the structure from 5 to 6 at 20 GPa. Hence pressure not only promotes an increase in the coordination number of the metal atoms but also a necessary concomitant increase in the coordination number of the O atoms. The bonded radii, determined at a lower pressure between 0.0 and 15 GPa for LaAlO3 and CaSnO3, decrease a smaller amount with the radii for the La and Ca atoms decreasing by 0.03 and 0.04 Å, respectively, while the radii for the smaller Al and Sn atoms decrease by 0.01 and 0.02 Å, respectively. In general, O atoms are more compressible than the metal atoms, but overall the calculations demonstrate that the bonded radii for the atoms in crystals are virtually incompressible when subjected to high pressure. The reason that the bonded radii change little when subjected to high pressure is ascribed to the changes in the effective interatomic potentials that result in increased repulsion when the atoms are squeezed together.

Halogen bonding interactions in the XC5H4N···YCF3 (X = CH3, H, Cl, CN, NO2; Y= Cl, Br, I) complexes.

The noncovalent interactions between the σ-hole region outside the halogen atom and the nitrogen atom of pyridine and its para-substituted derivatives are the focus of this work. Based on the analyses of the electrostatic potentials, YCF3 (Y = Cl, Br, I) act as halogen bond donors, XC5H4N (X = CH3, H, Cl, CN, NO2) act as halogen bond acceptors, and the binary halogen-bonded complexes XC5H4N···YCF3 have been designed and investigated by B3LYP-D3/aug-cc-pVDZ calculations together with the aug-cc-pVDZ-PP basis set for iodine. When the halogen bond acceptor remains unchanged, the interactions between C5H5N and YCF3 (Y = Cl, Br, I) increase with the order of Y = Cl, Br, and I. When the halogen donor ICF3 is fixed, the halogen bonding interactions decrease along the sequence of X = CH3, H, Cl, CN, NO2. Therefore, the halogen bond of the CH3C5H4N···ICF3 complex is the strongest. The interactions between Lewis acid YCF3 (Y = Cl, Br, I) and pyridine and para-substituted pyridine are closed-shell and noncovalent interactions. On the one hand, when the halogen bond acceptor XC5H4N is fixed, with the increase of halogen atomic number, the strength of halogen bond increases; on the other hand, when the halogen bond donor ICF3 is fixed, as the electron-withdrawing ability of the electron-withdrawing group (X) increases, the halogen bond gradually weakens.

Lanthanum and Lanthanide Trifluorides: Lanthanide Contraction and Volume of Fluorine Ion

Lanthanide contraction of lanthanum and 14 lanthanides (Ln), leading to a decrease in R3+ ionic radii by ~15% (with respect to the smallest one) with an increase in the element atomic number Z, is a way to implement a close packing of F1– ions in trifluorides of heavy 4f elements of the periodic table of elements. The efficiency of lanthanide (Ln) and actinide (An) contraction in the formation of inorganic fluoride crystals with a minimum unit-cell volume per fluorine ion (VF) is estimated. For AnF3 (An = Ac–Am), the VF value decreases from ~20 to ~17.4 A3 with an increase in Z from 89 to 95. The unavailability of heavy An makes this value final. The close packing of the fluorine ion in fluorides could not be obtained using the effects of lanthanide and actinide contraction and increase in the cation valence. Fluorides LnF3 (structure type β-YF3) from the end of the series from ErF3 (15.86 A3) to LuF3 (15.48 A3) are nearest to the anion close packing. The latter VF value is minimum among all studied LnF3 compounds and actinide fluorides (both simple and complex) and close to the saturation value. It corresponds to the estimated fluorine ionic radius of 1.246 A.

Applying machine learning optimization methods to the production of a quantum gas

We apply three machine learning strategies to optimize the atomic cooling processes utilized in the production of a Bose–Einstein condensate (BEC). For the first time, we optimize both laser cooling and evaporative cooling mechanisms simultaneously. We present the results of an evolutionary optimization method (differential evolution), a method based on non-parametric inference (Gaussian process regression) and a gradient-based function approximator (artificial neural network). Online optimization is performed using no prior knowledge of the apparatus, and the learner succeeds in creating a BEC from completely randomized initial parameters. Optimizing these cooling processes results in a factor of four increase in BEC atom number compared to our manually-optimized parameters. This automated approach can maintain close-to-optimal performance in long-term operation. Furthermore, we show that machine learning techniques can be used to identify the main sources of instability within the apparatus.

Experimental measurement of effective atomic numbers and albedo factors for some alloys using the backscattering technique

Alloys of the type Pb60Sn20ZnxCd(20-x) where x = 0, 5, 10, 15 or 20 were prepared by a conventional melt quench technique. The intensity distribution of backscattered photons from the radioactive isotopes 22Na and 137Cs (with photon energies of 511 keV and 662 keV, respectively) were recorded for different thicknesses of alloy samples and some metallic samples (Al, Zn, Sn and Pb) with use of a GAMMA-RAD5 spectrometer (76 mm × 76 mm NaI(Tl) scintillation detector). Backscattered photon intensities were plotted as a function of both the atomic number and the target thickness. A best fit curve was drawn between backscattered photon counts and the atomic number of the metallic samples, from which the effective atomic numbers (Zeff) of the alloys were obtained at a particular photon energy as well as thickness. The experimentally obtained Zeff values are in good agreement with the theoretical ones (based on mass attenuation coefficients from the WinXCom database). The plot of intensity versus thickness shows that the intensity of backscattered photons increases with sample thickness. The albedo factors (energy albedo, number albedo and dose albedo) were also determined experimentally at these photon energies for the alloys and metallic samples. In the Compton scattering dominant region, the albedo factors decrease with an increase in atomic number as well as with an increase in photon energy.

Monte Carlo simulation of thermophysical properties of liquid Ni-15%X (Co, Cu, Yb) alloys

In this paper, the embedded-atom method was used to study the influence of different solute elements (Co, Cu, Yb) on the thermophysical properties of liquid Ni-based alloys. By exploring the relationship between surface tension, viscosity, diffusion coefficient and temperature of liquid Ni-based alloys with three solutes in the range of 1500 ~ 1900 K, we found that under certain components the surface tension of liquid Ni-based alloys with three solutes decreased as temperature increased. Except the case that the atomic radius of the same period decreased with the increase of the atomic number and influence of lanthanide and actinide contraction, the surface tension of liquid Ni-based alloys decreased with the increase of atomic number. The viscosity of liquid alloy showed a downward trend with increasing temperature, and the viscosity decreased exponentially with the temperature increasing under certain components. The variation trend of diffusion coefficient of the three kinds of atoms was similar to that of the temperature, which increased with the increase of temperature under the same component. Especially, the diffusion coefficient increases exponentially with the increase of temperature under certain components. These simulated data provided necessary thermophysical parameters for non-equilibrium dynamics analysis of liquid-phase alloys and also supplied a sound theoretical basis for exploring the internal physical mechanism of “liquid microstructures–thermophysical properties–preferred phase of nucleation”.

Ab initio studies of the structural, electronic and magnetic properties of stannite CuFe2-III-VI4 (III = Al, Ga, In and VI = S, Se, Te) alloys

The structural, magnetic and electronic properties of stannite CuFe2-III-VI4 (where III = Al, Ga, In and VI = S, Se, Te) quaternary alloys were investigated using the full-potential augmented plane wave and local states approach as implemented in the Wien2K. The effects of exchange and correlation functional were parameterized according to the generalized gradient approximation (GGA) and GGA + U approaches. The calculated lattice constants for these alloys are in reasonable agreement with available experimental data. We find that the band gap width decreases as the anion atomic number increase in the CuFe2-III-VI4 alloys while keeping the cation unchanged. The electronic density of states reveals different electronic character such as half-semiconducting, half-metallic and metallic depending on the cation (group III atom) or anion (group VI atom) considered. The magnetic moments within the GGA + U approach, for all the alloys considered (CuFe2AlS4, CuFe2AlSe4, CuFe2AlTe4, CuFe2GaS4, CuFe2GaSe4, CuFe2InS4, CuFe2InSe4 and CuFe2InTe4) are 8 μB except for CuFe2GaTe4 alloy, which is 7.95 μB. The observed magnetism in these alloys is mainly from the 3d states of Cu and Fe atoms. In conclusion, the study presents a theoretical investigation on the CuFe2-III-VI4 alloys within the GGA and GGA + U approaches.

Phase change memory materials: Rationalizing the dominance of Ge/Sb/Te alloys

Rewritable optical storage is dominated by alloys of a small number of elements, overwhelmingly Ge, Sb, and Te. For over 30 years, Ge/Sb/Te alloys in the composition range ${(\mathrm{GeTe})}_{1\ensuremath{-}x}{({\mathrm{Sb}}_{2}{\mathrm{Te}}_{3})}_{x}\phantom{\rule{0.28em}{0ex}}(0\ensuremath{\le}x\ensuremath{\le}1)$ have been the materials of choice in commercial devices: all have metastable rock-salt structures that change little over decades at archival temperatures, and all contain vacancies (cavities). The special status of Ge/Sb/Te alloys arises from the close similarity of their valence orbitals as measured by the orbital radial moments, so that bonds are stronger than in other combinations of elements of groups 14--16 with appropriate valences. The orbital similarity arises from the irregular changes in atomic orbitals and properties as the atomic number increases (``secondary periodicity''). Jones showed [P. R. Soc. London, Ser. A 147, 396 (1934)] that the simple cubic structure of (metallic) Bi (valence configuration $6{s}^{2}6{p}^{3}$) is unstable to a distortion to a (semimetallic) rhombohedral structure. This picture can be adapted to Ge/Sb/Te alloys to explain the metastable structure of the above family of compounds where vacancies almost always occur next to Te atoms, which form one sublattice of the rock-salt structure. The disorder in the Ge/Sb/vacancy sublattice is not random.

One-step preparation of halogenated aminobenzonitrile modified g-C3N4 via copolymerization and in situ halogen doping for highly enhanced visible light hydrogen evolution

A series of halogenated aminobenzonitrile modified graphitic carbon nitride (g-C3N4) was prepared by a one-step calcination of dicyandiamide and 2-amino-5-halogen-benzonitriles (X-ABN, X = F, Cl, Br or I, 1.67 wt% of dicyandiamide) together, and named as X-ABN-CN. The resulting X-ABN-CN photocatalysts were characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, ultraviolet–visible diffuse reflection spectroscopy, and photoluminescence spectroscopy. The characterization results indicated that X-ABN-CN have been successfully prepared, and the π-conjugated system and electronic structure of X-ABN-CN could be improved via copolymerization, Ullmann reaction and in situ halogen doping. Under visible light irradiation (λ > 400 nm), the photocatalytic activity of X-ABN-CN were much higher than that of pure g-C3N4 and increase with the increase of halogen atomic number. The hydrogen evolution rate of I-ABN-CN (131.4 μmol h−1) was 7.4 times that of g-C3N4 (17.7 μmol h−1). Furthermore, the corresponding mesoporous X-ABN-CN (X-ABN-MCN, X = F, Cl, Br or I) were prepared by using SiO2 nanoparticles as template. As expected, I-ABN-MCN showed the highest photocatalytic activity in all mesoporous samples, which is about 8.8 times that of g-C3N4. The results manifest that the copolymerization, Ullmann reaction, in situ halogen doping and mesoporous structure could be integrated together to modify g-C3N4 by a simple one-step calcination process.

Trends in stability of rare earth pyrochlores in the lanthanide series: Ruthenium

Stability of lanthanide pyrochlores is important as they are proposed as rad-waste matrices. The molar Gibbs energy of formation data obtained was correlated with increase in atomic number down the lanthanide series for Ln2Ru2O7 where (Ln = Nd, Sm, Eu, Gd, Ho-Lu &Y). The enthalpies of formation of the ternary oxides from their component binary oxides at T/K = 298.15 were determined. The enthalpies of formation from oxides become less negative down the lanthanide series as the radius ratio Ln/Ru decreases. These thermodynamic data can be correlated to pyrochlores ability to withstand irradiation damage, an important input for the nuclear industry.

Ion-pairing in polyoxometalate chemistry: impact of fully hydrated alkali metal cations on properties of the keggin [PW12O40]3- anion.

The counterions of polyoxometalates (POMs) impact properties and applications of this growing class of inorganic clusters. Here, we used density functional theory (DFT) to elucidate the impact of fully hydrated alkali metal cations on the geometry, electronic structure, and chemical properties of the polyoxotungstate anion [PW12O40]3-. The calculations show that the HOMO of the free anion [PW12O40]3- is a linear combination of the 2p AOs of the bridging oxygens, and the first few LUMOs are the 5d orbitals of the tungsten atoms. The S0→ S1 electron excitation, near 3 eV, is associated with the O(2p) → W(5d) transition. Anion/cation complexation leads to formation of [PW12O40]3-[M+(H2O)16]3 ion-pair complexes, where with the increase of atomic number of M, the M+(H2O)16 cluster releases several water molecules and interacts strongly with the polyoxometalate anion. For M = Li, Na and K, [PW12O40]3-[M+(H2O)16]3 is characterized as a "hydrated" ion-pair complex. However, for M = Rb and Cs, it is a "contact" ion-pair complex, where the strong anion-cation interaction makes it a better electron acceptor than the "hydrated" ion-pair complexes. Remarkably, the electronic excitations in the visible part of the absorption spectrum of these complexes are predominantly solvent-to-POM charge transfer transitions (i.e. intermolecular CT). The ratio of the number of intermolecular charge transfer transitions to the number of O(2p)-to-W(5d) valence (i.e. intramolecular) transitions increases with the increasing atomic number of the alkali metals.

Hydration of Fluorobenzenes: A Molecular Dynamics Simulation Investigation

Molecular dynamics simulations of benzene and 12 fluorobenzenes with various degrees of fluorine substitution in water reveal that the accumulation of water in the first solvent shell decreases with increase in number of fluorine atoms relative to benzene, with an exception of hexafluorobenzene. Further, the solute–solute radial density function indicates that partially substituted fluorobenzenes sample $$ \uppi $$-stacked and T-shaped geometries. In contrast benzene and hexafluorobenzene sample only the T-shaped geometries. Comparison of solute–solute and solute–solvent radial density functions suggests that solute–solute interactions is preferred over solute–solvent interaction, which suggests the hydrophobic nature of fluorobenzenes, which increases with increase in number of fluorine atoms on the phenyl ring. The spatial distribution of water around the fluorobenzenes suggests that water avoids the C–F bond group, which indicates increase in hydrophobicity of fluorobenzenes with number of fluorine atoms.

Critical evaluation and thermodynamic assessment of the R2O–P2O5 (R = Li, Na and K) systems

The R2O–P2O5 (R = Li, Na and K) systems are thermodynamically optimized based on the evaluated phase equilibria and thermodynamic data by the CALPHAD method. Liquid phase is described by the Modified Quasichemical Model, which takes short-range ordering in liquid solution into account. All intermediate phases RPO3, R5P3O10, R4P2O7 and R3PO4 are treated as stoichiometric compounds and the corresponding polymorphic transitions are considered. A set of self-consistent model parameters for describing the Gibbs free energy of each phase are obtained. The experimental phase equilibria, enthalpy of formation, entropy, heat capacity and activity are reproduced well within experimental error limits. The calculated liquidus around compounds become flatter with the increase of P2O5 content, suggesting that the degree of stability of phosphate increases as its composition approaches R3PO4. The calculated enthalpies of formation for intermediate compounds become more negative and entropies become more positive with the increase of atomic numbers of alkali metals.

The kinetic study of the methane oxidation reaction catalyzed by transition metal oxides RuO/RhO/PdO

ABSTRACTThe relative stability and kinetics of CH4 … O2 … MO and the reaction potential energy surface under the transition metal oxide catalysts (RuO/RhO/PdO) during methane oxidation reaction were studied with density functional calculations. The results show that the reaction can be easily carried out under the catalysis of transition metal oxides. The transition barriers and the reaction rate constant all show oscillation modes that are consistent with the increase of atomic number at 298 K. while the calculated reaction energies (Er/kcal mol−1) are gradually increased. The oxidised dioxide can be treated to form metal and oxygen that can still be used as a catalyst for methane oxidation; the resulting oxygen can continue to be used as an oxidant. We also calculated the rate constant of methane oxidation reaction to give the resulting methanol pathway. The calculated dynamic characterisation shows that the rate constant has a positive temperature dependence. Our calculation show that this reaction is exothermic reaction via the RuO/RhO/PdO catalyst, and the reaction is thermodynamically feasible. This study also provides theoretical reference data for us to identify new catalysts for the catalytic oxidation of methane.

Measurement of interdiffusivity for fcc_A1 Co-V-W alloys

Combining the solid-solid diffusion couples and the electron probe microanalysis (EPMA) technique, the composition profiles of 15 ternary diffusion couples within single fcc_A1 Co-V-W alloys at 1373, 1423 and 1473 K were measured in the present work. The interdiffusivities were evaluated by means of composition profiles applied to Matano-Kirkaldy method, in which the uncertainties were calculated by error propagation and the reliability was validated via thermodynamic constraints. According to the measured main interdiffusivities D˜VVCo and D˜WWCo, it is found that the diffusion of V in fcc_A1 Co is faster than that of W in fcc_A1 Co. The ternary main interdiffusion coefficients of D˜VVCo and D˜WWCo at different compositions were compared with the ones for boundary binary CoV and CoW systems in the literature. A normalized ternary interdiffusivity diagram, in which the ternary interdiffusivities D˜VVCo and D˜WWCo are plotted against the normalized ration of x(W)/(x(W) + x(V)), is proposed in the present work. Meanwhile, comprehensive comparisons of main interdiffusivity D˜XXCo in fcc_A1 Co-W-X (X = Al, V, Cr, Mo) alloys and D˜YYCoin fcc_A1 Co-V-Y (Y = Al, Ti, Mo, W) alloys indicate that both of the main interdiffusivities decrease with the increase of atomic number. The present work provides interdiffusivties for the establishment of a kinetic database to computationally design the multi-component cemented carbides.

Ferromagnetic, antiferromagnetic, and Peierls distortion states in IVA-VA nanoribbons

Based on first-principles density-functional theory calculations, we have systematically investigated the electronic and magnetic properties of zigzag IVA-VA nanoribbons (ZIV-VNRs). We find that the ZIV-VNRs can exhibit ferromagnetic semiconducting ground states for CP and CAs while simultaneously exhibiting antiferromagnetic states for SiP and SiAs in their edges. What is more, their spin-polarized energy and magnetic moment are quite large in such special systems. Further, we find that a Peierls-like distortion semiconducting state could also take place when the bonding of the edge state is weaker enough as the atom number increases. The physical origin is the competition between charge, spin, and lattice degrees of freedom in different localization characteristics of ZIV-VNR edge states' p orbitals. Our work provides a route for potential functionalities of spintronics devices at the nanoscale.