Bismuth Atoms Research Articles

Surface segregation of bismuth atoms in Ag-Bi alloys (based on results obtained by traditional electrochemical methods and the laser heating-induced temperature potential shift)

The time effects observed on mechanically renewed electrodes of eutectic-type Ag–Bi alloys in NaF solutions in the potential range of ideal polarizability are studied by traditional electrochemical methods: cyclic voltammetry and electrochemical impedance spectroscopy. The observed effects are shown to be a result of surface segregation of Bi atoms (enrichment of the metal surface layer by these atoms) realized at a rate very high as compared with usual solid-state processes. The analysis of these data carried out in the framework of phenomenological models made it possible the assumption that the mechanism of surface (not bulk) diffusion is responsible for the “anomalously” high rate of electrode surface enrichment with Bi atoms to be substantiated. The additional information on the segregation processes at the interface of Ag–Bi electrode with NaF solution acquired by the method of laser heating-induced temperature potential shift correlates with the results of electrochemical investigations.

Structural characteristics of amorphous K-Bi citrate (De-Nol) and its aqueous solutions from EXAFS spectra

EXAFS (Extended X-ray Absorption Fine Structure) spectra of an amorphous solid Bi complex with citrate (known as De-Nol) and its aqueous solutions in a wide concentration range are measured. For the solutions good agreement is revealed between their structural parameters and the averaged interatomic distances and coordination numbers of the crystalline polymeric bismuth citrate compound composed of 12-nuclear Bi clusters based on the structure Bi12O22. So, it is found that droplets of the colloidal solution have a core structure close to the solid Bi12O22 cluster structure. When the concentrated solution is diluted the cluster structure is somewhat modified, it remaining similar to the structure of the Bi12O22 cluster and even at a tenfold dilution and the nearest (oxygen) spheres of the Bi environment changing insignificantly. The appearance in this case of an additional oxygen atom at a large distance from the bismuth atom likely due to the presence of the oxygen atom from the hydroxyl group of the diluted aqueous solution. The appearance of such oxygen is in accordance with particles size increase for diluted solution obtained by small-angle X-ray diffraction measurements. It is established that the structure of the amorphous solid complex is multiphase and, as a whole, similar to the structure of the solid binuclear complexes.

EXTREME PRESSURE SYNERGISTIC MECHANISM OF BISMUTH NAPHTHENATE AND SULFURIZED ISOBUTENE ADDITIVES

A four-ball tester was used to evaluate the tribological performances of bismuth naphthenate (BiNap), sulfurized isobutene (VSB), and their combinations. The results show that the antiwear properties of BiNap and VSB are not very visible, but they possess good extreme pressure (EP) properties, particularly sulfur containing bismuth additives. Synergistic EP properties of BiNap with various sulfur-containing additives were investigated. The results indicate that BiNap exhibits good EP synergism with sulfur-containing additives. The surface analytical tools, such as X-ray photoelectron spectrometer (XPS) scanning electron microscope (SEM) and energy dispersive X-ray (EDX), were used to investigate the topography, composition contents, and depth profile of some typical elements on the rubbing surface. Smooth topography of wear scar further confirms that the additive showed good EP capacities, and XPS and EDX analyzes indicate that tribochemical mixed protective films composed of bismuth, bismuth oxides, sulfides, and sulfates are formed on the rubbing surface, which improves the tribological properties of lubricants. In particular, a large number of bismuth atoms and bismuth sulfides play an important role in improving the EP properties of oils.

Reactivity Indexes of Fullerene and Bismullene Mixed Clusters: How the Intruders Modify the Properties.

In this investigation, the feasibility of functionalizing fullerene and bismullene with Bi and C as intruders is theoretically explored. The systems analyzed are C60-xBix (with x = 0-10, fullerene-like) and Bi60-yCy (with y = 0-10, bismullene-like). Optimized geometries, reactivity indexes, and highest occupied molecular orbital to lowest unoccupied molecular orbital (HOMO-LUMO) gaps (for analyzing the potential application of these molecules as materials for solar cells) are reported. The most stable structures of bismullene-like systems have cage geometries. The most stable fullerene-like geometries resemble a cup with bismuth atoms at the edge of the bowl. The presence of intruders increases the electron acceptor power and decreases the electron donor power in most cases. HOMO-LUMO gaps indicate that bismullene-like clusters represent better candidates for building solar cells than fullerene-like clusters. This information could be useful for future experiments.

Solvent-Driven Reductive Activation of CO2 by Bismuth: Switching from Metalloformate Complexes to Oxalate Products.

In this work, we investigated how the reductive activation of CO2 with an atomic bismuth model catalyst changes under aprotic solvation. IR photodissociation spectroscopy of mass-selected [Bi(CO2 )n ]- cluster ions was used to follow the structural evolution of the core ion with increasing cluster size. We interpreted the IR spectra by comparison with density-functional-theory calculations. The results show that CO2 binds to a bismuth atom in the presence of an excess electron to form a metalloformate ion, BiCOO- . Solvation with additional CO2 molecules leads to the stabilization of a bismuth(I) oxalate complex and results in a core ion switch.

The effect of Ag, Pb and Bi impurities on grain boundary sliding and intergranular decohesion in Copper

We investigate the changes in grain boundary sliding (GBS) and intergranular decohesion in copper (Cu), due to the inclusion of bismuth (Bi), lead (Pb) and silver (Ag) substitutional impurity atoms at a symmetric tilt grain boundary (GB), using a first-principles concurrent multiscale approach. We first study the segregation behavior of the impurities by determining the impurity segregation energy in the vicinity of the GB. We find that the energetically preferred sites are on the GB plane. We investigate the intergranular decohesion of Cu by Bi and Pb impurities and compare this to the effect of Ag impurities by considering the work of separation, and the tensile strength, . Both and decrease in the presence of Bi and Pb impurities, indicating their great propensity for intergranular embrittlement, whilst the presence of Ag impurities has only a small effect. We consider GBS to assess the mechanical properties in nanocrystalline metals and find that all three impurities strongly inhibit GBS, with Ag having the biggest effect. This suggests that Ag has a strong effect on the mechanical properties of nanocrystalline Cu, even though its effect on the intergranular decohesion properties of coarse-grained Cu is not significant.

Tris(5-bromo-2-methoxyphenyl)bismuth bisbenzenesulfonate solvate with toluene: Synthesis and structure

Tris(5-bromo-2-methoxyphenyl)bismuth bisbenzenesulfonate, which crystallizes from toluene in the solvate form (5-Br-2-MeOC6H3)3Bi(OSO2Ph)2 • TolH (I), has been synthesized by the reaction between tris(5-bromo-2-methoxyphenyl)bismuth and benzenesulfonic acid in the presence of hydrogen peroxide (1: 2: 1 mol/mol/mol) in ether. A crystal contains two types of crystallographically independent molecules (a and b), in which bismuth atoms have a trigonal bipyramidal coordination to benzenesulfonate substituents in axial positions. The axial OBiO angle is 175.4(3)° (Ia) and 175.5(3)° (Ib), and the equatorial CBiC angles are 111.2(3)°, 122.0(4)°, 126.7(4)° (Ia) and 111.3(4)°, 123.3(3)°, 125.2(4)° (Ib). The Bi–C distances are 2.189(9), 2.198(9), 2.200(10) A (Ia) and 2.198(9), 2.202(9), 2.209(9) A (Ib). The Bi–O bond lengths are 2.274(8), 2.306(8) A (Ia) and 2.248(8), 2.303(8) A (Ib). Intramolecular contacts between the bismuth atom and the oxygen atoms of methoxy and sulfonate groups take place in molecules.

Density, viscosity, ultrasound velocity, and electrical resistivity of the eutectic lead–bismuth melt

The temperature dependences of the density, the dynamic viscosity, the ultrasound velocity, and the electrical resistivity of the liquid lead–bismuth eutectic are investigated over a wide temperature range. Anomalies in the temperature dependences of the ultrasound velocity and the resistivity are found at 580 K. These anomalies are associated with the formation of groups of bismuth atoms near the eutectic temperature. The isothermal and adiabatic compressibilities are determined for the first time over a wide temperature range.

Structure of Gd0.95Bi0.05Fe3(BO3)4 single crystals at 293 and 90 K

The structure of GdFe3(BO3)4 single crystals has been studied by X-ray diffraction at 293 and 90 K. The crystals are grown from a flux in the Bi2Mo3O12–B2O3–Li2MoO4–Gd2O3–Fe2O3 system. The results of chemical analysis and structural study show that these crystals contain bismuth as an impurity. It is found that bismuth atoms are located at gadolinium sites in the structure. A decrease in the temperature is accompanied by a lowering of the symmetry from sp. gr. R32 (at 293 K) to sp. gr. P3121 (at 90 K). The presence of two types of iron chains with different geometries at 90 K promotes a change in the magnetic properties of these crystals with a decrease in the temperature.

Topologically Protected Metallic States Induced by a One-Dimensional Extended Defect in the Bulk of a 2D Topological Insulator.

We report ab initio calculations showing that a one-dimensional extended defect generates topologically protected metallic states immersed in the bulk of two-dimensional topological insulators. We find that a narrow extended defect, composed of periodic units consisting of one octagonal and two pentagonal rings (a 558 extended defect), embedded in the hexagonal bulk of a bismuth bilayer, introduces two pairs of one-dimensional counterpropagating helical-Fermion electronic bands with the opposite spin-momentum locking characteristic of the topological metallic states that appear at the edges in two-dimensional topological insulators. Each one of these pairs of helical-Fermion bands is localized, respectively, along each one of the zigzag chains of bismuth atoms at the core of the 558 extended defect, and their hybridization leads to the opening of very small gaps (6 meV or less) in the helical-Fermion dispersions of these defect-related modes. We discuss the connection between the defect-induced metallic modes and the helical-Fermion edge states that occur on bismuth bilayer ribbons.

Local Structural Distortion Induced Uniaxial Negative Thermal Expansion in Nanosized Semimetal Bismuth.

The corrugated layer structure bismuth has been successfully tailored into negative thermal expansion along c axis by size effect. Pair distribution function and extended X-ray absorption fine structure are combined to reveal the local structural distortion for nanosized bismuth. The comprehensive method to identify the local structure of nanomaterials can benefit the regulating and controlling of thermal expansion in nanodivices.

Synthesis and structure of tris(3-methylphenyl)bismuth bis(3,4-dimethylbenzenesulfonate)

Tris(3-methylphenyl)bismuth bis(3,4-dimethylbenzenesulfonate) has been synthesized via the reaction of tris(3-methylphenyl)bismuth, 3,4-dimethylbenzenesulfonic acid, and hydrogen peroxide (1: 2: 1) in diethyl ether. Bismuth atoms in the product molecule have the trigonal bipyramidal coordination with arenesulfonate substituting groups in the axial positions.

Unexpected orbital magnetism in Bi-rich Bi2Se3 nanoplatelets

The discovery of two-dimensional electron gas states with giant Rashba spin splitting (RSS) in electron-doped three-dimensional topological insulators (TIs) uncovered new fascinating physics and raised hopes for novel spintronic devices. Significant challenges, including synthetic constraints and control of the magnetic properties, must be addressed before any breakthroughs are possible. Here, we show how RSS in Bi-rich Bi2Se3 nanoplatelets is responsible for the appearance of remarkable orbital magnetic properties, as observed using magnetization and conduction electron spin resonance experiments and confirmed by theoretical simulations. In view of the strong spin-orbit coupling (SOC) and the proximity to the TI surface states, this discovery enlightens fundamental aspects of SOC-based functionalities of TI materials with aims for future applications. Plate-like bismuth nanocrystals can give physicists enriched mechanisms to control spin through unexpected, surface-localized magnetism. Topological insulators have crystal structures that make them non-conductive everywhere except for the quantized states on their surfaces. Hae Jin Kim's group at KBSI and co-workers (PI, “Demokritos”, and UoI) has now used a liquid-phase, solvothermal synthesis to turn bismuth selenide (Bi2Se3) topological insulators into nanometre-thin platelets with unique hexagonal shapes. The team discovered that sandwiching bismuth atoms between the nanohexagons disrupts the normal coupling interactions between electron spin and orbital motion at topological insulators surface states. This splitting generates so-called Rashba states that produce a special orbital-based type of magnetism, where spin states can be flipped with help from a weak magnetic field. Further spin engineering of this system is possible by altering the degree of bismuth intercalation. Bi-layer intercalation in Bi2Se3 nanoplatelets gives rise to an intriguing crystal structure comprised of randomly stacked Bi2Se3 and Bi2Se2. Detailed conduction electron spin resonance (CESR) and AC/DC magnetization studies prove that controlling Bi intercalation results in fine tuning the two-dimensional electron gas parabolic Rashba states, which enables the appearance of extraordinary orbital magnetism, through the coupling of the spin and orbital degrees of freedom. The methodology presented herein provides a unique and simple way for efficient spin engineering, with important potential applications.

Triphenylbismuth bis(3,4-dimethylbenzenesulfonate): Synthesis and structure

Triphenylbismuth bis(3,4-dimethylbenzenesulfonate) Ph3Bi(OSO2C6H3Me2-3,4)2 (I) has been synthesized by the reaction between triphenylbismuth and 3,4-dimethylbenzenesulfonic acid in the presence of tert-butylhydroperoxide (1: 2: 1 mol) in ether. The bismuth atom in complex I has a trigonal bipyramidal coordination to arenesulfonates substituents in axial positions (axial OBiO angle, 173.99(8)°; equatorial CBiC angles, 106.94(11)°, 112.24(11)°, 140.77(11)°). The Bi‒C distances are 2.189(3), 2.192(3), and 2.197(3) A; the Bi‒O distances are 2.284(2) and 2.301(2) A. Some intramolecular contacts are observed between the central atom and the oxygen atoms of sulfonate groups at the maximum equatorial angle (Bi···O 3.122(3), 3.189(4) A).

Crystal Structures of MBi2Br7 (M = Rb, Cs) – Filled Variants of AX7 Sphere Packing

AbstractThe reinvestigation of the pseudo‐binary systems MBr–BiBr3 (M = Rb, Cs) revealed two new phases with composition MBi2Br7. Both compounds are hygroscopic and show brilliant yellow color. The crystal structures were solved from X‐ray single crystal diffraction data. The isostructural compounds adopt a new structure type in the triclinic space group P$\bar{1}$. The lattice parameters are a = 755.68(3) pm, b = 952.56(3) pm, c = 1044.00(4) pm, α = 76.400(2)°, β = 84.590(2)°, γ = 76.652(2)° for RbBi2Br7 and a = 758.71(5) pm, b = 958.23(7) pm, c = 1060.24(7) pm, α = 76.194(3)°, β = 83.844(4)°, γ = 76.338(3)° for CsBi2Br7. The crystal structures consist of M+ cations in anticuboctahedral coordination by bromide ions and bromidobismuthate(III) layers 2∞[Bi2Br7]–. The 2D layers comprise pairs of BiBr6 octahedra sharing a common edge. The Bi2Br10 double octahedra are further connected by common vertices. The bismuth(III) atoms increase their mutual distance in the double octahedra by off‐centering so that the BiBr6 octahedra are distorted. The CsBi2Br7 type can be interpreted as a common hexagonal close sphere packing of M and Br atoms, in which 1/4 of the octahedral voids are filled by Bi atoms. The structure type was systematically analyzed and compared with alternative types of common packings. The existence of a compound with the suggested composition CsBiBr4 could not be verified experimentally.

New Environment for a Two-Dimensional Topological Insulator with Hexagonal Channels Hosting Diiodido-bismuthate(I) Anions in a Singlet State

A honeycomb layer of transition metal-centered bismuth cubes has attracted attention as part of the weak topological insulator (TI) Bi14Rh3I9. The intermetallic layer itself is a two-dimensional TI and has been found in Bi13Pt3I7 and Bi12Pt3I5, as well as in the new material Bi38Pt9I14, yet with different stacking sequences and types of insulating spacer layers in all cases. The arrangements strongly influence the electronic situation, especially the coupling between the TI layers. X-ray diffraction and electron microscopy show that in Bi38Pt9I14 the intermetallic layers are exclusively separated by single layers of iodide ions. The eclipsed stacking of the honeycomb layers results in hexagonal channels. These host hitherto unknown linear [BiI2]− anions with bismuth atoms in the uncommon +I oxidation state. Quantum chemical calculations as well as magnetic susceptibility data indicate a singlet state stabilized by strong spin–orbit coupling. Bi38Pt9I14 is a semiconductor with a very narrow energy gap, as ...

The Process of Dispersing Bismuth Atoms into Iridium via an Intermediate Monolayer of Graphite

It is first revealed by thermodesorption spectroscopy that when bismuth atoms diffuse the indium atoms through an intermediate graphite layer, they show certain characteristic features. In the Ir (111)-C system at 1400 K δ = 0.4 ± 0.05 and diffusion δBi = Ndif/N = 2.5 × 10-3 bismuth atoms in the Ir(111)-C system. The amount of intercalated and diffused bismuth depends on the electrical field, i.e., on the positive potential in the Ir(111)-C system. It has been noted that a considerable diffusion of bismuth into iridium started at 180 V and increased up to 3000 V. The activation energies for bismuth diffusion into and from iridium were calculated to be En1 = 6.05 ± 0.05 eV and E1n = 6.3 ± 0.1 eV, respectively.

Prediction of neutral noble gas insertion compounds with heavier pnictides: FNgY (Ng = Kr and Xe; Y = As, Sb and Bi).

A novel class of interesting insertion compounds obtained through the insertion of a noble gas atom into the heavier pnictides have been explored by various ab initio quantum chemical techniques. Recently, the first neutral noble gas insertion compounds, FXeY (Y = P, N), were theoretically predicted to be stable; the triplet state was found to be the most stable state, with a high triplet-singlet energy gap, by our group. In this study, we investigated another noble gas inserted compound, FNgY (Ng = Kr and Xe; Y = As, Sb and Bi), with a triplet ground state. Density functional theory (DFT), second order Møller-Plesset perturbation theory (MP2), coupled-cluster theory (CCSD(T)) and multi-reference configuration interaction (MRCI) based techniques have been utilized to investigate the structures, stabilities, harmonic vibrational frequencies, charge distributions and topological properties of these compounds. These predicted species, FNgY (Ng = Kr and Xe; Y = As, Sb and Bi) are found to be energetically stable with respect to all the probable 2-body and 3-body dissociation pathways, except for the 2-body channel leading to the global minimum products (FY + Ng). Nevertheless, the finite barrier height corresponding to the saddle points of the compounds connected to their respective global minima products indicates that these compounds are kinetically stable. The structural parameters, energetics, and charge distribution results as well as atoms-in-molecules (AIM) analysis suggest that these predicted molecules can be best represented as F(-)[(3)NgY](+). Thus, all the aforementioned computed results clearly indicate that it may be possible to experimentally prepare the most stable triplet state of FNgY molecules under cryogenic conditions through a matrix isolation technique.

Surface alloying and iron selenide formation inFe/Bi2Se3(0001)observed by x-ray absorption fine structure experiments

The atomic structure of ultrathin iron films deposited on the (0001) surface of the topological insulator ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ is analyzed by surface x-ray absorption spectroscopy. Iron atoms deposited on a ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ (0001) surface kept at 160 K substitute bismuth atoms within the first quintuple layer. Iron atoms are neighbored by six selenium atoms at a distance in the 2.4 \AA{} range indicating substantial atomic relaxations. Mild annealing up to 520 K leads to the formation of $\ensuremath{\alpha}$-FeSe, characterized by a local order extending up to the sixth shell (5.80 \AA{}). Ab initio calculations predict a noncollinear magnetic ordering with a transition temperature of 3.5--10 K depending on the iron concentration and the number of the layers in which Fe is located.

Synthesis, crystal structures, DNA interaction and anticancer activity of organobismuth(V) complexes

We have synthesized three novel organobismuth(V) complexes Ph3Bi(OOCC6H3F2)21, Ph3Bi(OOCC6H4CF3)22 and Ph3Bi(OOCC4H3S)23, and their structures were characterized by IR spectroscopy, elemental analysis, 1H NMR and single crystal X-ray diffraction. X-ray crystallography showed that all of the bismuth atoms adopt distorted trigonal–bipyramidal geometries. The complex molecules lead to one-dimensional chain structure and two-dimensional network structure through C–H…X (X=O, F, C) interactions. The interaction of the complex 1 with calf-thymus DNA (CT-DNA) was investigated by UV absorption spectroscopy, fluorescence emission spectroscopy and viscosity. All results revealed that the complex 1 binds to DNA via a intercalative mode. Furthermore the proliferation inhibitory activities of the three complexes on MDA-MB-231 breast cancer cells were investigated. The results indicated that all of the three complexes have superior inhibition of cellular proliferation.