Bismuth Atoms Research Articles

InGaAsPBi grown on InP substrate by gas source molecular beam epitaxy

The effects of growth condition on material quality of quinary alloy InGaAsPBi grown by gas source molecular beam epitaxy (GSMBE) were investigated systematically. It is found that 0.1% of Bi incorporation can play the role of surfactant effects and is beneficial to improve the material quality. The roughness of surface RMS measured by atomic force microscope (AFM) is 0.218 nm. Furthermore, the addition of a small amount of bismuth atoms promotes the binding of phosphorus atoms to group III atmos.

New Order in (BiS)1.19(Bi1/3Cr2S4) Misfit Layer Compound.

AbstractIn a sample with nominal composition BiCr2S5 a new misfit layer compound has been synthesized and studied via transmission electron microscopy (TEM). It presents a composite modulated structure with a composition that can be formulated as (BiS)1.19[(CrS2)‐Bi1/3‐(CrS2)]. It consists of the periodic stacking of a Q layer (BiS) with two H layers (CrS2), …QHHQHH…, with additional bismuth atoms inserted between the H layers. Selected area electron diffraction (SAED) patterns show an almost commensurate fit between the pseudo‐tetragonal Q (BiS) and the pseudo‐orthohexagonal H (Bi1/3Cr2S4) subcells along the misfit direction a, being b the same for both sublattices and c the layers stacking direction. In addition to the characteristic misfit modulation between the two sub‐structures, a second modulation is observed in the H sub‐structure produced by the ordering of bismuth atoms within the Van der Waals gap that occurs between consecutive H layers. High resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy (STEM) images show ordered stacking sequences between the (BiS) and (Bi1/3Cr2S4) layers. Besides, disordered intergrowths have been occasionally found as well as different kinds of twinning defects.

Phosphorescent Bismoviologens for Electrophosphorochromism and Visible Light-Induced Cross-Dehydrogenative Coupling

A series of novel bismuth-bridged viologen analogues, bismoviologens (BiV2+), synthesized through a combination of a bismuth atom and viologen skeleton is reported. Their optical and electrochemical properties were fine-tuned through the N-arylation or N-alkylation reactions. Bismolviologens not only showed good redox properties but also exhibited phosphorescence under ambient conditions (in air at room temperature). This phenomenon makes BiV2+ the first examples of phosphorescent viologen analogues reported to date. On the basis of the excellent and unique redox and optical properties of BiV2+, their electrophosphorochromic devices were fabricated. Furthermore, BiV2+ was used for the first time as both a photocatalyst and electron mediator in visible light-induced cross-dehydrogenative coupling reactions.

Синтез и строение бис(бут-3-еноата) трифенилвис-мута

As a result of the interaction of triphenylbismuth and vinylacetic acid with tert-butyl hydroperoxide at ambient temperature in ether, a new compound triphenylbismuth bis(but-3-enoate) Ph3Bi(O2CCH2CH=CH2)2 was obtained with the 60% yield, and the melting point of 131 °C. In the IR spectrum of the substance recorded in the KBr pellet on an “IR Prestige-21” set, Shimadzu, Japan, in the range of 4000–400 cm–1, the signals of valence vibration (v, cm–1) were found to equal 3054 (Ph-H), 2978 (CH2), 1600 (C=C), 1599 (COO-as); 1471, 1439, 1362 (COO-s), 919, 734, 680; 573 (Bi-C), 454 (Bi-O). In the 1H NMR spectrum taken in deuterochloroform on an Agilent DD2 400 spectrometer, the following signals were detected: 8.15 (dd, J = 8.3, 1.0 Hz, 6H), 7.59 (t, J = 7.6 Hz, 6H), 7.46 (dd, J = 11.0, 3.7 Hz, 3H), 5.76 (td, J = 17.1, 6.9 Hz, 2H), 4.96–4.86 (m, 4H), 2.86 (dt, J = 6.9, 1.3 Hz, 4H). 13C NMR: 40.44 (2C, -CH2-), 116.70 (2C, CH2=), 130.71 (3C, Ph), 131.13 (6C, Ph), 132.34 (6C, Ph), 133.90 (2C, =CH-), 160.38 (3C, Bi-C), 177.43 (2C, C=O). The molecular structure of the compound was found by X-ray diffraction. X-ray diffraction was performed on an Oxford Diffraction Gemini Sapphire3 diffractometer using Mo Ka radiation (λ = 0.71073 Å, graphite monochromator) at T = 293 K. P21/s, a = 12.7672(3), b = 22.0170(4), c = 8.9767(17) Å, β = 104.831(2)º, V = 2439.25(9) Å3, Z = 4. The bismuth atom in the structure has a distorted trigonal-bipyramidal coordination. The O-Bi-O axial angle is 171.5 (2)°. The Bi–O and Bi-C bond lengths are 2.280(4)–2.310(3) and 2.197(7)–2.209(6) Å.

Electronic band structure of Bi-intercalate layers in graphene and SiC(0001)

A potential way to tune the electronic band structure of graphene is to intercalate foreign atoms in the interface between graphene and substrate. However, such an intercalate layer covered by graphene is difficult to directly study with microscopic probes, and relatively little is known about its crystal and electronic structures. In this work, we study epitaxial graphene on SiC(0001) intercalated by bismuth atoms by means of angle-resolved photoemission spectroscopy. We reveal the electronic band structure of Bi-intercalate layers, from which we could identify two distinct phases, one is metallic and the other is insulating. The metallic phase composed of closely packed Bi atoms shows nearly free electron bands that are repeated to follow the period of SiC(0001)-(1 $$\times $$ 1). The lower coverage insulating phase shows characteristic flat bands in the period of SiC(0001)-( $$\sqrt{3} {\times } \sqrt{3}$$ )R30 $$^\circ $$ with respect to the surface lattice constant of SiC(0001). Even though there exists such two distinct phases in the Bi intercalate layer, the doping level of graphene is found to vary rather continuously with the coverage of Bi. Based on the observed band structures and Bi 5d core-level spectra, we suggest a structural model for the metallic and insulating phases of Bi-terminated SiC(0001).

Analysis of physical dose enhancement in nano-scale for nanoparticle-based radiation therapy: a Cluster and endothelial cell model

Objective(s): One major difficulty of conventional radiotherapy is the lack of selectivity between the tumor and the organs at risk. In nanoparticle aided radiotherapy, heavy elements are present at higher concentrations in the tumor than normal tissues. This study aimed to model the characteristics of secondary electrons generated from the interaction of clusters comprised of five different nanoparticles including Gold, Gadolinium, Iridium, Bismuth, and Hafnium atoms with low energy x-rays (similar to brachytherapy sources in terms of energy) as a function of nanoparticle size and beam energy. Materials and Methods: To better evaluate the contributions of secondary electrons in energy deposition, and also to develop a framework in analyzing further measurements in the future, we attempted to enhance and promote existing mathematical models for energy deposition in endothelial cells by nanoparticle-enhanced radiotherapy. Also, the MCNPX Monte Carlo code was used to model the identical geometry and the dose enhancement factor was calculated for all types of simulated nano-clusters.Results: Our results showed that for our model consist of a nano-cluster and an endothelial cell the DEF significantly depends on the energy of photons and L- and K-edge binding energy of the atoms inside the nano-cluster. However, for Gd at the energy 60 keV, a higher dose enhancement factor was seen.Conclusion: It can be concluded that the mathematical model considers the DEF variation with photon energy and the effect of NP type is considered in DEF calculations. However, the MC method has indicated very high sensitivity to photon energy, and NP type compared to the mathematical method.

Mechanistic insight of KBiQ2 (Q = S, Se) using panoramic synthesis towards synthesis-by-design.

Solid-state synthesis has historically focused on reactants and end products; however, knowledge of reaction pathways, intermediate phases and their formation may provide mechanistic insight of solid-state reactions. With an increased understanding of reaction progressions, design principles can be deduced, affording more predictive power in materials synthesis. In pursuit of this goal, in situ powder X-ray diffraction is employed to observe crystalline phase evolution over the course of the reaction, thereby constructing a “panoramic” view of the reaction from beginning to end. We conducted in situ diffraction studies in the K–Bi–Q (Q = S, Se) system to understand the formation of phases occurring in this system in the course of their reactions. Powder mixtures of K2Q to Bi2Q3 in 1 : 1 and 1.5 : 1 ratios were heated to 800 °C or 650 °C, while simultaneously collecting diffraction data. Three new phases, K3BiS3, β-KBiS2, and β-KBiSe2, were discovered. Panoramic synthesis showed that K3BiQ3 serves an important mechanistic role as a structural intermediate in both chalcogen systems (Q = S, Se) in the path to form the KBiQ2 structure. Thermal analysis and calculations at the density functional theory (DFT) level show that the cation-ordered β-KBiQ2 polymorphs are the thermodynamically stable phase in this compositional space, while Pair Distribution Function (PDF) analysis shows that all α-KBiQ2 structures have local disorder due to stereochemically active lone pair expression of the bismuth atoms. The formation of the β-KBiQ2 structures, both of which crystallize in the α-NaFeO2 structure type, show a boundary where the structure can be disordered or ordered with regards to the alkali metal and bismuth. A cation radius tolerance for six-coordinate cation site sharing of ∼ 1.3 is proposed. The mechanistic insight the panoramic synthesis technique provides in the K–Bi–Q system is progress towards the overarching goal of synthesis-by-design.

Investigation on Electronic and Thermoelectric Properties of (P, As, Sb) Doped ZrCoBi

Since the last decade, the half-Heusler (HH) compounds have taken an important place in the field of the condensed matter physics research. The multiplicity of substitutions of transition elements at the crystallographic sites X, Y and (III-V) elements at the Z sites, gives to the HH alloys a multitudes of remarkable properties. In the present study, we examined the structural, electronic and thermoelectric properties of ZrCoBi0.75Z0.25 (Z = P, As, Sb) using density functional theory (DFT). The computations have been done parallel to the full potential linearized augmented plane wave (FP-LAPW) method as implemented in the WIEN2k code. The thermoelectrically properties were predicted via the semi-classical Boltzmann transport theory, as performed in Boltztrap code. The obtained results for the band structure and densities of states confirm the semiconductor (SC) nature of the three compounds with an indirect band gap, which is around 1eV. The main thermoelectric parameters such as Seebeck coefficient, thermal conductivity, electrical conductivity and figure of merit were estimated for temperatures ranging from zero to 1200K. The positive values of Seebeck coefficient (S) confirm that the ZrCoBi0.75Z0.25 (x = 0 and 0.25) are a p-type SC. At the ambient temperature, ZrCoBi0.75P0.25 exhibit the large S value of 289 µV/K, which constitutes an improvement of 22% than the undoped ZrCoBi, and show also a reduction of 54% in thermal conductivity (κ/τ). The undoped ZrCoBi has the lowest ZT value at all temperatures and by substituting bismuth atom by one of the sp elements (P, As, Sb), a simultaneous improvement in κ/τ and S have led to maximum figure of merit (ZT) values of about 0.84 obtained at 1200 K for the three-doped compounds.

Embrittlement: A Crack Tip View

Normally tough structural materials may fail catastrophically when contaminated with even minuscule quantities of ubiquitous elements such as sulfur, phosphorus or hydrogen. These so called embrittling elements exert their influence at the tip of atomically sharp cracks where applied stress is concentrated to a degree given by the stress concentration factor. When the concentrated stress exceeds the strength of the bonds across the crack tip, the crack will run. Hence, an element may embrittle a host either by decreasing bond strength and/or increasing the stress concentration. While the effects of embrittling elements on the earlier have been extensively studied, less attention has been directed to their effects on the latter. Here we exploit the nearsightedness of electronic matter principle to provide a measure of the stress concentration factor and study its changes in the presence of a known embrittling element. We find that for the well studied system of copper embrittled by dilute quantities of bismuth, bismuth atoms increase the crack tip stress concentration by more than 60%

Cubane and cubanoid: Structural, optoelectronic and thermodynamic properties from DFT and TD-DFT method

In this paper, we report structural, electronic and optical properties of cubane (C8H8) and cubanoids (cubane-like molecules) using Density Functional Theory (DFT). The cubanoids are cubanes for which Carbon atoms have been substituted by Nitrogen (N), Phosphorus (P), Boron (B), Silicon (Si), Arsenic (As), Antimony (Sb) or Bismuth (Bi) atoms. These molecules presented exceptional stability with several different symmetry point groups, being the majority Td. All calculated vibrational frequencies are positive for any studied molecules indicating that all these structures are in a stable state. The HOMO-LUMO gaps and DOS were calculated converged towards to values between 1.87 eV and 5.61 eV, actually showing promising electronic properties (Just for comparison, the cubane energy gap is 7.50 eV). The optical absorptions were also calculated for the cubanoid structure using the Time-Dependent Density Functional Theory (TD-DFT). Their dependence on the wavelength is analyzed, where five of theses structures absorb on the visible region. Finally, the extrapolation of thermodynamic properties indicates that these cubanoid could be potentially synthesized spontaneously, where four structures, the synthesis would occur for temperatures below 400 K, while for Si4Bi4H4 structure, the synthesis would occur at room temperature.

Engineering BiVO4@Bi2S3 heterojunction by cosharing bismuth atoms toward boosted photocatalytic Cr(VI) reduction

The photocatalytic efficiency is limited by poor charge separation efficiency and high carrier transport activation energy (CTAE) of photogenerated electron/hole pairs than traditional semiconductor. Hybridizing nanostructure with two staggered alignment band structure is proved as an effective strategy to mitigate these two challenges but still suffers a strong coulomb electrostatic repulsive force between two heterogeneous semiconductors. Here, we steer a friendly sulfurization process to construct BiVO4@Bi2S3 heterojunction with a scenario of cosharing Bi atoms. The intimate atomic-level contact between BiVO4 and Bi2S3 not only enhances the visible-light absorption and lowers CTAE, but also accelerate carrier’s separation efficiency, which enables it to deliver the best photocatalytic performance toward reduction of Cr(VI). BiVO4@Bi2S3 only needs less than 40 min to completely reduce 50 ppm Cr(VI) solution. The type II heterojunction photocatalytic mechanism is systematically studied to decipher the carriers’ transfer track between BiVO4 and Bi2S3. Our new finding of engineering inorganic heterojunction by cosharing atoms opens a new avenue to other similar materials for potential applications.

Structural and biological features of bismuth(III) halide complexes with heterocyclic thioamides

Ten novel bismuth(III) halide complexes of [Bi(L)X3]n, [Bi(L)2×3]2, and [Bi(L)3×3] structural types were synthesized, in which L: 5-ethoxy-2-mercaptobenzimidazole, 5‑methoxy-2-mercaptobenzimidazole and N-methylbenzothiazole. Bismuth(III) halide complexes 1–10 were characterized by melting point, elemental analysis, molar conductivity, FT-IR, FT-Raman, UV-Visible, 1H and 13C NMR spectroscopic techniques, as well as by the Thermogravimetric-Differential Thermal Analysis (TG-DTA). The crystal structures of complexes 1–10 were determined by using single crystal X-ray diffraction study. The results show that the bismuth(III) complexes exist as monomer (4), doubly-bridged dimer (1–3 and 5–9), and edge-sharing polymer (10), in which the central bismuth atom is a six-coordinated and adopts distorted octahedral geometries. We report here, for the first time, cis-sulfur, cis-halide arrangement of the doubly-bridged dimer bismuth(III) complexes. The intermolecular interactions in bismuth(III) complexes play a very important role in the supramolecular architecture. A detailed analysis of the intermolecular interactions has been performed as based on the Hirshfeld surfaces and their associated two-dimensional fingerprint plots. Bismuth(III) halide complexes 1–10 and their free ligands have been screened for antimicrobial activity against two Gram negative bacteria (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853) and two Gram positive bacteria (Staphylococcus aureus ATCC 25923 and Enterococcus faecalis ATCC 29212). The influence of complexes 1–10 and the free ligands on the catalytic peroxidation of the linoleic acid by the enzyme lipoxygenase (LOX) has been determined experimentally and theoretically.

Bismuth atom tailoring of indium oxide surface frustrated Lewis pairs boosts heterogeneous CO2 photocatalytic hydrogenation

The surface frustrated Lewis pairs (SFLPs) on defect-laden metal oxides provide catalytic sites to activate H2 and CO2 molecules and enable efficient gas-phase CO2 photocatalysis. Lattice engineering of metal oxides provides a useful strategy to tailor the reactivity of SFLPs. Herein, a one-step solvothermal synthesis is developed that enables isomorphic replacement of Lewis acidic site In3+ ions in In2O3 by single-site Bi3+ ions, thereby enhancing the propensity to activate CO2 molecules. The so-formed BixIn2-xO3 materials prove to be three orders of magnitude more photoactive for the reverse water gas shift reaction than In2O3 itself, while also exhibiting notable photoactivity towards methanol production. The increased solar absorption efficiency and efficient charge-separation and transfer of BixIn2-xO3 also contribute to the improved photocatalytic performance. These traits exemplify the opportunities that exist for atom-scale engineering in heterogeneous CO2 photocatalysis, another step towards the vision of the solar CO2 refinery.

1,1′-2-Trisubstituted ferrocenyl dibismuthines containing N / O donor pendant arm

New unsymmetrical chiral 1,1′-2-ferrocenyl dibismuthines [(C5H4)(BiPh2)]Fe(2-{Me2NCH(R)}C5H3)(BiPh2) containing 2-[(Me2NCH(R)] where R = Me (1) or H (3) pendant arm on ferrocenyl ring were synthesized. An unsymmetrical 1,1′-ferrocenyl-bismuthine (5) in a low yield and 1,1′-2-ferrocenyl chlorodibismuthine (11) as an impurity were also isolated from the reaction mixture. Furthermore, Monoammonium salt [CpFe{2-(Me3N+CH2)C5H3}(BiPh2)2][I−] (6) and 1,1´,2-vinylferrocenyl dibismuthine derivative (7) were obtained by the reaction of CH3I with (3) and (1) respectively. The nucleophilic substitution reaction of (6) by o-hydroxyacetaphenone, salicylaldehyde, and N-methyl piperazine in acetonitrile gave the new functionalized 1,1′-2-substituted ferrocenyl dibismuthines [(C5H4)(BiPh2)]Fe[{2-(RCH2)C5H3}BiPh2] where R = OC6H4-2-C(O)Me (8), OC6H4-2-C(O)H (9) and N(CH2CH2)2NMe (10) respectively with different N or O containing pendant arm. 1,2-disubstituted ferrocenyl compounds presented in this work present planar chirality. These new compounds were characterized by IR, 1H-NMR, 13C-NMR spectroscopy, and High-Resolution Mass Spectrometry (HRMS). The X-ray structures of 1,1´,2-trisubstituted ferrocenyl dibismuthines (10) and (11) were determined. The molecular structure of (11) shows hypervalent Bi···N bonding in the solid-state. The compound (11) has planar chirality, central chirality, and Bi center-chirality with pseudo-trigonal bipyramidal geometry (see-saw structure) around the chiral Bi center while the other bismuth atom has distorted trigonal pyramidal geometry. The variable temperature 1H-NMR spectra of compound (3) in −40°C to 40°C range in CDCl3 indicates a lack of Bi···N coordination.

FeBiS2Cl – A new iron-containing member of the MPnQ 2 X family

Abstract The new sulfochloride FeBiS2Cl is obtained as a black powder following a mechanochemical synthesis procedure. The product crystallizes in the orthorhombic space group Cmcm (no. 63) with lattice parameters a = 3.82142(7), b = 12.2850(2) and c = 9.2911(2) Å. While the iron atom has an octahedral coordination environment, the bismuth atom is coordinated in the form of a bicapped trigonal prism. Both cation polyhedra form alternating layers, for iron built up of corner sharing octahedra along the c axis and edge sharing ones along the a axis. The bismuth polyhedra are connected through shared faces along the c axis and common edges along the a axis. Because of the distribution of sulfur and chlorine on a mixed anion site, the bismuth atoms occupy split positions. Experimental observations are supported by theoretical calculations.

Design of a novel carbon/BiOBr nanosheet photoanode and its photoelectrochemical application

A novel carbon/BiOBr (C/BiOBr) photoanode with interesting electronic structure is designed. Carbon atoms are connected with bismuth (Bi) and bromine (Br) atoms by electron interaction. Such an electron interaction changes the chemical environments of Bi and Br, so that results in enhanced visible light absorption capacity and high transfer rate of charge carriers. Photoelectrochemical cell (PEC) system has been constructed to study the photoelectrochemical property of C/BiOBr photoanode. The short-circuit current (Jsc) and open-circuit voltage (Voc) of C/BiOBr are measured to be 0.057 mA/cm2 and 0.296 V, which are higher than that in PEC with the pristine BiOBr photoanode. The proposed chemically bonded C/BiOBr photoanode offers potential for electricity generation and pollutants degradation.

A Robust and Low-Power Bismuth Doped Tin Oxide Memristor Derived from Coaxial Conductive Filaments.

Memristor, processing data storage and logic operation all-in-one, is an advanced configuration for next generation computer. In this work, a bismuth doped tin oxide (Bi:SnO2 ) memristor with ITO/Bi:SnO2 /TiN structure has been fabricated. Observing from transmission electron microscope (TEM) for the Bi:SnO2 device, it is found that the bismuth atoms surround the surface of SnO2 crystals to form the coaxial Bi conductive filament. The self-compliance current, switching voltage and operating current of Bi:SnO2 memristor are remarkably smaller than that of ITO/SnO2 /TiN device. With the content of 4.8% Bi doping, the SET operating power of doped device is 16 µW for ITO/Bi:SnO2 /TiN memory cell of 0.4 × 0.4 µm2 , which is cut down by two orders of magnitude. Hence, the findings in this study suggest that Bi:SnO2 memristors hold significant potential for application in low power memory and broadening the understanding of existing resistive switching (RS) mechanism.

Top-down fabrication of bromine doped Bi2O3 nanowires with efficient charge separation for photoelectrochemical application

Photoanode material, as the core component of photoelectrochemical cell, has attracted great research interest. Here, bromine doped Bi2O3 nanowires (BBON) are achieved through a simple top-down method. Bromine doping changes the chemical environment of bismuth and oxygen atoms, and also changes the band edge position. As a result, BBON photoanode with efficient charge separation shows excellent photoelectrochemical and photocatalytic activity. The electricity generation property of BBON in the photoelectrochemical cell system is investigated. The short-circuit current density (Jsc) and open-circuit voltage (Voc) are measured to be 0.6045 μA/cm2 and 0.318 V, which is higher than that of bulk Bi2O3 photoanode. BBON is a possible candidate photoanode material and provides potential for electricity generation and pollutants degradation.

Temperature-dependent study of GaAs1−x−yNxBiy alloys for band-gap engineering: photoreflectance and k · p modeling

Photoreflectance measurements were performed for GaAs1−x−yNxBiy layers in the temperature range of 20–300 K. For each sample a transition related to the band-gap was observed, which red-shifts with increasing nitrogen and bismuth content. The temperature dependencies of the band-gap were fitted by the Varshni and Bose–Einstein formulas and simulated within the band anticrossing model of the interaction between the extended band states of the GaAs and the localized states associated with nitrogen and bismuth atoms. The reduction of the band-gap was found to be ∼80–100 meV.

Synthesis and Structure of Two Phosphate Representatives Formed by Metal Cations in Oxidation State III, α-CaMg2(SO4)3 Analogues

Polycrystals of the BiFe2(PO4)3 compound and Bi1 – xSbхCr2(PO4)3 solid solution, which form a family isostructural to α-CaMg2(SO4)3 (sp. gr. P63/m), have been synthesized from an aqueous solution by the salt co-precipitation method. The samples are characterized by X-ray diffraction, IR spectroscopy, differential thermal analysis, and thermogravimetry, microprobe analysis. The BiFe2(PO4)3 single crystals have been grown by the flux method. The structure consists of polyhedra of three types: PO4 tetrahedra, two face-sharing FeO6 octahedra, and BiO6 octahedra. Isolated PO4 tetrahedra, which share oxygen vertices with doubled FeO6 octahedra, form a three-dimensional [Fe2(PO4)3]3∞ framework, whose voids are occupied by bismuth atoms. Structures of the BiFe2(PO4)3 and NASICON types are compared.