Bismuth Chalcogenides Research Articles

Biocompatibility of Bi2Se3 regarding primary mixed retinal cells

Abstract Bismuth chalcogenides have a groundbreaking impact on materials science because of their potential applications in spintronics and optoelectronics, especially for their properties as topological insulators. Investigation of the biocompatibility of the electrode material at the tissue/electrode interface is essential to assess the use of topological insulators in bioelectronics. Here, we addressed the biocompatibility of Bi2Se3 by demonstrating that porcine primary mixed retinal cells can survive on its surface with or without poly-D-lysine/laminin coating. Neuronal and glial cell survival were demonstrated using cell culture and imaging techniques. These results highlight the promising potential of Bi2Se3 for integration into bioelectronic devices, particularly for the development of neural interfaces and other biomedical applications.

Phase diagram for the quasi-binary thallium(I) selenide–bismuth(III) telluride system

The phase diagram for the quasi-binary Tl2Se–Bi2Te3 system has been established based on the results of phase studies by differential thermal analysis (DTA) and X-ray diffraction (XRD). The diagram for the title system presented in this paper has been compared with that previously published by other authors. As a result of the research, a significant correction of the former phase diagram was made, because it was found that the components of the studied system formed three new chemical compounds. Obtained phase diagram has been compared with other thallium(I)–bismuth(III) chalcogenide systems.

Zipserite, a new bismuth chalcogenide Bi5(S,Se)4 from Nagybörzsöny in Hungary with a R$\bar{3}$m(00γ)00 modulated structure

AbstractZipserite is a new mineral species discovered in a sample collected from the old mine dumps of the abandoned epithermal deposit Nagybörzsöny in Hungary. Zipserite occurs as anhedral to subhedral, lath-like grains, up to 500 μm in size, in hydrothermally strongly altered rocks. It is found at a contact between bismuth and bismuthinite, also associated with rare ikunolite and joséite-A. Zipserite is silvery white with a metallic lustre. Mohs hardness is ca. 2–3 and the calculated density is 7.815 g.cm–3. In reflected light, zipserite is grey–white, with colour and reflectance essentially matching those of bismuthinite. Bireflectance is weak, internal reflections not present. Anisotropy is moderately strong, with dark blue and grey colours of anisotropy. Reflectance values for the four Commission on Ore Mineralogy wavelengths of zipserite in air [Rmax, Rmin (%) (λ in nm)] are: 48.4, 46.4 (470); 47.8, 45.9 (546); 47.8, 45.8 (589); and 47.5, 45.6 (650). The empirical formula, based on electron-microprobe analyses, is (Bi4.74Pb0.31)Σ5.05(S3.38Se0.56Te0.02)Σ3.96, that can be simplified as Bi5(S,Se)4. The ideal end-member formula of zipserite is Bi5S4, which requires Bi 89.07 and S 10.93, total 100 wt.%. Zipserite possesses a fascinating crystal structure. The average structure is trigonal, with space group P$\bar{3}$m, a = 4.162(1) Å, c = 16.397(1) Å, V = 245.94(4) Å3 and Z = 2. The structure is built by the alternation of a double bismuth layer Bi2 and the Bi3S4 block which is a three octahedra thick layer. Its general formula can be expressed as Bi2 + Bi3S4, which corresponds directly to the observed stacking. At 98 K, the structure can be described using the superspace formalism with an R-centred trigonal unit cell a = 4.209(2) Å, c0 = 5.616(6) Å, a modulation vector q ≈ 4/3 c* and the superspace group R$\bar{3}$m(00γ)00. Zipserite is not only a new mineral but also the first named member of a new sub-group of compounds within the broader family of bismuth chalcogenides, characterised by complex stacking of structural units (Bi2 layers and Bi3S4 blocks). Some of these phases are being investigated as promising thermoelectric materials and synthetic analogues of zipserite could also be inspected for similar physical properties.

Constraints on Ore Genesis from Trace Ore Mineralogy: A New Occurrence of Kupčíkite and Paděraite from the Zhibula Cu Skarn Deposit, Southern Tibet

Mineral assemblages containing Cu-Bi sulfosalts, Bi chalcogenides, and Ag-(Au) tellurides have been identified in the mid-Miocene Zhibula Cu skarn deposit, Gangdese Belt, southern Tibet. Different mineral assemblages from three locations in the deposit, including proximal massive garnet skarn, proximal retrogressed pyroxene-dominant skarn in contact with marble, and distal banded garnet–pyroxene skarn hosted in marble, are studied to constrain the evolution of the mineralization. Hypogene bornite contains elevated Bi (mean 6.73 wt.%) and co-exists in proximal andradite skarn with a second bornite with far lower Bi content, carrollite, Au-Ag tellurides (hessite, petzite), and wittichenite. This assemblage indicates formation at relatively high temperatures (>400 °C) and high fS2 and fTe2 during prograde-stage mineralization. Assemblages of Bi sulfosalts (wittichenite, aikinite, kupčíkite, and paděraite) and bismuth chalcogenides (e.g., tetradymite) in proximal pyroxene skarn are also indicative of formation at relatively high temperatures, but at relatively lower fTe2 and fS2 conditions. Within the reduced distal skarn (chalcopyrite–pyrrhotite-bearing) in marble, cobalt, and nickel occur as discrete minerals: cobaltite, melonite and cobaltic pentlandite. The trace ore mineral signature of the Zhibula skarn and the distributions of precious and critical trace elements such as Ag, Au, Co, Te, Se, and Bi support an evolving magmatic–hydrothermal system in which different parts of the deposit each define ore formation at distinct local physicochemical conditions. This is the first report of kupčíkite and paděraite from a Chinese location. Their compositions are comparable to other occurrences, but conspicuously, they do not form nanoscale intergrowths with one another.

Thermoelectric properties of the bismuth oxychalcogenides Bi2SO2, Bi2SeO2 and Bi2TeO2

We present a detailed theoretical study of the thermoelectric properties of the bismuth oxychalcogenides Bi2ChO2 (Ch = S, Se, Te). The electrical transport is modelled using semi-classical Boltzmann transport theory with electronic structures from hybrid density-functional theory, including an approximate model for the electron lifetimes. The lattice thermal conductivity is calculated using first-principles phonon calculations with an explicit treatment of anharmonicity, yielding microscopic insight into how partial replacement of the chalcogen in the bismuth chalcogenides impacts the phonon transport. We find very good agreement between the predicted transport properties and a favourable cancellation of errors that allows for near-quantitative predictions of the thermoelectric figure of merit ZT. Our calculations suggest recent experiments on n-doped Bi2SeO2 have achieved close to the largest ZT possible in bulk materials, whereas the largest reported ZT for Bi2TeO2 could be improved sixfold by optimising the carrier concentration. We also predict that much larger ZT > 2.5, competitive with the benchmark thermoelectric SnSe, could be obtained for Bi2SO2 and Bi2SeO2 with heavy p-type doping. This study demonstrates the predictive power of this modelling approach for studying thermoelectrics and highlights several avenues for improving the performance of the Bi2ChO2.

High‐Index and Low‐Loss Topological Insulators for Mid‐Infrared Nanophotonics: Bismuth and Antimony Chalcogenides

AbstractTopological insulators generally have dielectric bulk and conductive surface states. Consequently, some of these materials are shown to support polaritonic modes at visible and THz frequencies. At the same time, the optical properties of topological insulators in the mid‐infrared (mid‐IR) remain poorly investigated. Here, near‐field imaging is employed to probe the mid‐IR response from the exfoliated flakes of bismuth (Bi)/selenide (Se)/telluride (Te)/antimony (Sb) crystals with varying stoichiometry – Bi2Se3, Bi2Te2Se, and Bi1.5Sb0.5Te1.7Se1.3 – in pristine form as well as covered by thin flakes of hexagonal boron nitride (hBN) is employed. Contrary to theoretical expectations, all three materials exhibit a dielectric response with a high refractive index and with a loss below the experimental detection limit. Particularly, the near‐field mapping of propagating phonon‐polaritons in hBN demonstrates that all three van der Waals crystals with different stoichiometry act as a practically lossless dielectric substrate with an ultra‐high refractive index of up to 7.5 in Bi2Te2Se. Such a unique dielectric crystal will be of great advantage for numerous nanophotonic applications in the mid‐IR.

Bismuth chalcogenide topological insulators crystals grown by the optical floating zone technique

In this paper, two procedures for the growth of both binary and ternary single crystals of bismuth chalcogenides by optical floating zone technique are described. Detailed characterization has been carried out on a series of samples, i.e. Bi2SexTe3-x, with x = 0 and 0.9, and Bi2-xSbxSe3, with x = 0 and 0.15, to isolate high quality single crystals, essential for an accurate study of the physical properties of the materials. Systematic compositional and structural analysis on the samples grown by the two different procedures have been compared to infer the optimal growth parameters to obtain the largest possible single crystals. The c-axis lattice parameter of Bi1.85Sb0.15Se3 is reported here for the first time.

The coexistence of high piezoelectricity and superior optical absorption in Janus Bi2X2Y (X = Te, Se; Y = Te, Se, S) monolayers.

Bismuth chalcogenide and its derivatives have been attracting attention in various fields as semiconductors or topological insulators. Inspired by the high piezoelectric properties of Janus Bi2TeSeS monolayer and the excellent optical absorption properties of the Bi2X3 (X = Te, Se, S) monolayers, we theoretically predicted four new-type two-dimensional (2D) monolayers Janus Bi2X2Y (X = Te, Se; Y = Te, Se, S) using the first principles combined with density functional theory (DFT). The thermal, dynamic, and mechanical stabilities of Janus Bi2X2Y monolayers were confirmed based on ab initio molecular dynamics (AIMD) simulations, phonon dispersion, and elastic constants calculations. Their elastic properties, band structures, piezoelectric, and optical properties were systematically investigated. It was found that Janus Bi2X2Y monolayers have a typical Mexican hat-shaped valence band edge structure and, therefore, have a ring-shaped flat band edge, which results in their indirect band gaps. The results show that Janus Bi2X2Y monolayers are semiconductors with moderate band gaps (0.62-0.98 eV at the HSE + SOC level). After considering the electron-phonon renormalization (EPR), the band gaps are reduced by less than 5% at 0 K under the zero-point renormalization (ZPR) and further reduced by approximately 10% at 300 K. Besides, Janus Bi2X2Y monolayers also exhibit excellent optical absorption properties in the blue-UV light region, with the peak values at the order of 8 × 105 cm-1. Particularly, the Janus Bi2Te2S monolayer was found to exhibit a piezoelectric strain coefficient d11 of up to 20.30 pm V-1, which is higher than that of most of the 2D materials. Our results indicate that Janus Bi2X2Y monolayers could be promising candidates in solar cells, optical absorption, and optoelectronic devices; especially, a Janus Bi2Te2S monolayer can also be an excellent piezoelectric material with great prospects in the fields of mechanical and electrical energy conversion.

The effect of charged particle irradiation on the transport properties of bismuth chalcogenide topological insulators: a brief review.

Topological insulators (TIs) offer a novel platform for achieving exciting applications, such as low-power electronics, spintronics, and quantum computation. Hence, the spin-momentum locked and topologically nontrivial surface state of TIs is highly coveted by the research and development industry. Particle irradiation in TIs is a fast-growing field of research owing to the industrial scalability of the particle irradiation technique. Unfortunately, real three-dimensional TI materials, such as bismuth selenide, invariably host a significant population of charged native defects, which cause the ideally insulating bulk to behave like a metal, masking the relatively weak signatures of metallic topological surface states. Particle irradiation has emerged as an effective technique for Fermi energy tuning to achieve an insulating bulk in TI along with other popularly practiced methods, such as substitution doping and electrical gating. Irradiation methods have been used for many years to enhance the thermoelectric properties of bismuth chalcogenides, predominantly by increasing carrier density. In contrast, uncovering the surface states in bismuth-based TI requires the suppression of carrier density via particle irradiation. Hence, the literature on the effect of irradiation on bismuth chalcogenides extends widely to both ends of the spectrum (thermoelectric and topological properties). This review attempts to collate the available literature on particle irradiation-driven Fermi energy tuning and the modification of topological surface states in TI. Recent studies on particle irradiation in TI have focused on precise local modifications in the TI system to induce magnetic topological ordering and surface selective topological superconductivity. Promising proposals for TI-integrated circuits have also been put forth. The eclectic range of irradiation-based studies on TI has been reviewed in this manuscript.

Synthesis and enhanced room-temperature thermoelectric properties of CuO-MWCNT hybrid nanostructured composites.

This work presents the synthesis of novel copper oxide-multiwalled carbon nanotube (CuO-MWCNT) hybrid nanostructured composites and a systematic study of their thermoelectric performance at near-room temperatures as a function of MWCNT wt% in the composite. The CuO-MWCNT hybrid nanostructured composites were synthesized by thermal oxidation of a thin metallic Cu layer pre-deposited on the MWCNT network. This resulted in the complete incorporation of MWCNTs in the nanostructured CuO matrix. The thermoelectric properties of the fabricated CuO-MWCNT composites were compared with the properties of CuO-MWCNT networks prepared by mechanical mixing and with the properties of previously reported thermoelectric [CuO]99.9[SWCNT]0.1 composites. CuO-MWCNT hybrid composites containing MWCNTs below 5 wt% showed an increase in the room-temperature thermoelectric power factor (PF) by ∼2 times compared with a bare CuO nanostructured reference thin film, by 5-50 times compared to mixed CuO-MWCNT networks, and by ∼10 times the PF of [CuO]99.9[SWCNT]0.1. The improvement of the PF was attributed to the changes in charge carrier concentration and mobility due to the processes occurring at the large-area CuO-MWCNT interfaces. The Seebeck coefficient and PF reached by the CuO-MWCNT hybrid nanostructured composites were 688 μV K-1 and ∼4 μW m-1 K-2, which exceeded the recently reported values for similar composites based on MWCNTs and the best near-room temperature inorganic thermoelectric materials such as bismuth and antimony chalcogenides and highlighted the potential of CuO-MWCNT hybrid nanostructured composites for applications related to low-grade waste heat harvesting and conversion to useable electricity.

Modifying Electronic Structure of Bismuth Telluride Through S Doping and Te Vacancy Engineering for Enhanced Zn-Ion Storage Ability in Aqueous Zn-proton Hybrid Ion Batteries.

Bismuth chalcogenides are used as cathode materials in Zn-proton hybrid ion batteries, which exhibit an ultraflat discharge plateau that is favorable for practical applications. Unfortunately, their capacity is not competitive, and their charge storage mechanisms are ambiguous, both of which hinder their further development. In this study, S-doped Bi2Te3- x (SBT) nanosheets are prepared by tellurizing a Bi2O2S precursor using a hydrothermal process. As revealed by density functional theory analyses, the S dopant and its induced Te vacancies can distinctly manipulate the electronic structure of SBT, resulting in decent electrical conductivity and more negative adsorption energy to Zn2+. These advantages boost the Zn2+ storage ability of SBT materials. Consequently, compared with defect-free Bi2Te3, the SBT cathodes have superior specific capacity, rate capability, and cycling stability.

Strength Characteristics of the Materials Based on n- and p-Type Solid Solutions of Bismuth and Antimony Chalcogenides Fabricated by Various Methods

Strength Characteristics of the Materials Based on n- and p-Type Solid Solutions of Bismuth and Antimony Chalcogenides Fabricated by Various Methods

Nitrogen and phosphorus substitution driven optical anisotropy in bismuth chalcogenides [formula omitted] (X=Bi, N, P; Y=S, Se) from visible to IR region

In this study, we present structural, electronic and optical properties of bare and nitrogen, phosphorus substituted orthorhombic bismuth chalcogenide XBi7Y12 (X = Bi, N, P; Y=S, Se) within the framework of Density Functional Theory (DFT). The energy released during the formation of XBi7Y12 shows the favourability of the substitution. The substituted systems showed a systematic tunability of the energy band gap in the IR region. We predicted PBi7Se12 new direct band gap semiconductor having energy gap of 0.30 eV. The effective mass analysis studies were used to identify the type of newly designed semiconductor. The obtained results revealed that carrier effective mass for hole are lower than electron effective masses indicating the expected p-type conductivity in substituted systems. Appearance of a new energy peak near 0.88 eV in the imaginary part of dielectric function makes NBi7Y12 optically active in the IR region which extends their application over a wide spectral range. The optical response of the bare and substituted systems showed light polarization dependence in the IR and visible region indicating their potential towards photo-diodes, photo-catalysis, and photo-detectors.

Terahertz Third-Harmonic Generation in Topological Insulators Based on Bismuth and Antimony Chalcogenides

Terahertz third-harmonic generation in topological insulators based on bismuth and antimony chalcogenides has been experimentally investigated. It has been found that the third-harmonic conversion efficiency is inversely proportional to the electron Fermi energy; among the materials under study, antimony telluride has the highest conversion efficiency.

Modification of the Emission Spectrum of a Quantum Emitter in the Vicinity of Bismuth Chalcogenide Microparticles

We examine theoretically the effect of bismuth chalcogenide microparticles on the spontaneous emission of a double-V-type quantum emitter in free space. We have found, in particular, that the presence of a single microparticle causes a high degree of quantum interference in the way the quantum emitter releases energy in the process of spontaneous emission. This, in turn, leads to significant changes in the spectrum of the emitted energy. The quantum emitter’s initial state is crucial to how the energy is released in the presence of the microparticle. This observation has potential implications for quantum computing, particularly for reading the state of atomic qubits. When two microparticles are present, the effect is more pronounced, particularly when the quantum emitter is located in the gap between the particles.

Single-particle properties of topological Wannier excitons in bismuth chalcogenide nanosheets

We analyze the topology, dispersion, and optical selection rules of bulk Wannier excitons in nanosheets of Bi2Se3, a topological insulator in the family of the bismuth chalcogenides. Our main finding is that excitons also inherit the topology of the electronic bands, quantified by the skyrmion winding numbers of the constituent electron and hole pseudospins as a function of the total exciton momentum. The excitonic bands are found to be strongly indirect due to the band inversion of the underlying single-particle model. At zero total momentum, we predict that the s-wave and d-wave states of two exciton families are selectively bright under left- or right-circularly polarized light. We furthermore show that every s-wave exciton state consists of a quartet with a degenerate and quadratically dispersing nonchiral doublet, and a chiral doublet with one linearly dispersing mode as in transition metal dichalcogenides. Finally, we discuss the potential existence of topological edge states of chiral excitons arising from the bulk-boundary correspondence.

Positive and Negative Changes in the Electrical Conductance Related to Hybrid Filler Distribution Gradient in Composite Flexible Thermoelectric Films Subjected to Bending

P-type multiwalled carbon nanotubes (MWCNTs), as well as heterostructures fabricated by direct deposition of inorganic thermoelectric materials as antimony and bismuth chalcogenides on MWCNT networks are known as perspective materials for application in flexible thermoelectric polymer-based composites. In this work, the electrical response of three types of Sb2Te3-MWCNT heterostructures-based flexible films-free standing on a flexible substrate, encapsulated in polydimethylsiloxane (PDMS), and mixed in polyvinyl alcohol (PVA) is studied in comparison with the flexible films prepared by the same methods using bare MWCNTs. The electrical conductance of these films when each side of it was subsequently subjected to compressive and tensile stress during the film bending down to a 3 mm radius is investigated in relation to the distribution gradient of Sb2Te3-MWCNT heterostructures or bare MWCNTs within the film. It is found that all investigated Sb2Te3-MWCNT films exhibit a reversible increase in the conductance in response to the compressive stress of the film side with the highest filler concentration and its decrease in response to the tensile stress. In contrast, free-standing and encapsulated bare MWCNT networks with uniform distribution of nanotubes showed a decrease in the conductance irrelevant to the bending direction. In turn, the samples with the gradient distribution of the MWCNTs, prepared by mixing the MWCNTs with PVA, revealed behavior that is similar to the Sb2Te3-MWCNT heterostructures-based films. The analysis of the processes impacting the changes in the conductance of the Sb2Te3-MWCNT heterostructures and bare MWCNTs is performed. The proposed in this work bending method can be applied for the control of the uniformity of distribution of components in heterostructures and fillers in polymer-based composites.

Прочностные характеристики материалов на основе твердых растворов халькогенидов висмута и сурьмы р- и n-типов проводимости, полученных различными методами

Прочностные характеристики материалов на основе твердых растворов халькогенидов висмута и сурьмы р- и n-типов проводимости, полученных различными методами

Prospects of copper–bismuth chalcogenide absorbers for photovoltaics and photoelectrocatalysis

The distinct electronic structure of the Cu3BiS3 compound (wittichenite) leads high optical absorption and suitable bandgap, making it promising for photovoltaics and photoelectrochemical applications.

Bi2 Te3 /Bi2 Se3 /Bi2 S3 Cascade Heterostructure for Fast-Response and High-Photoresponsivity Photodetector and High-Efficiency Water Splitting with a Small Bias Voltage.

Large-scale multi-heterostructure and optimal band alignment are significantly challenging but vital for photoelectrochemical (PEC)-type photodetector and water splitting. Herein, the centimeter-scale bismuth chalcogenides-based cascade heterostructure is successfully synthesized by a sequential vapor phase deposition method. The multi-staggered band alignment of Bi2 Te3 /Bi2 Se3 /Bi2 S3 is optimized and verified by X-ray photoelectron spectroscopy. The PEC photodetectors based on these cascade heterostructures demonstrate the highest photoresponsivity (103mAW-1 at -0.1V and 3.5mAW-1 at 0V under 475nm light excitation) among the previous reports based on two-dimensional materials and related heterostructures. Furthermore, the photodetectors display a fast response (≈8ms), a high detectivity (8.96×109 Jones), a high external quantum efficiency (26.17%), and a high incident photon-to-current efficiency (27.04%) at 475nm. Due to the rapid charge transport and efficient light absorption, the Bi2 Te3 /Bi2 Se3 /Bi2 S3 cascade heterostructure demonstrates a highly efficient hydrogen production rate (≈0.416mmolcm-2 h-1 and ≈14.320µmolcm-2 h-1 with or without sacrificial agent, respectively), which is far superior to those of pure bismuth chalcogenides and its type-II heterostructures. The large-scale cascade heterostructure offers an innovative method to improve the performance of optoelectronic devices in the future.