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1.
Solution‐Based Synthesis of Layered Intergrowth Compounds of the Homologous PbmBi2nTe3n+m Series as Nanosheets
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Arindom Chatterjee Dr. Kanishka Biswas 《Angewandte Chemie (International ed. in English)》2015,54(19):5623-5627
Layered intergrowth compounds in the homologous PbmBi2nTe3n+m family are interesting because they are examples of natural heterostructures. We present a simple solution‐based synthesis of two‐dimensional nanosheets of PbBi2Te4, Pb2Bi2Te5, and PbBi6Te10 layered intergrowth compounds, which are members of the PbmBi2nTe3n+m [that is, (PbTe)m(Bi2Te3)n] homologous series. Few‐layer nanosheets exhibit narrow optical band gaps (0.25–0.7 eV) with semiconducting electronic‐transport properties. 相似文献
2.
A New Strategy for Realizing the Conversion of “Homo–Hetero–Homo” Heteroepitaxial Growth in Bi2Te3 and the Thermoelectric Performance
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Dr. Wei Guo Jianmin Ma Jiaqin Yang Di Li Qing Qin Caiying Wei Prof. Wenjun Zheng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(19):5657-5664
Uncovering the reason for structure‐dependent thermoelectric performance still remains a big challenge. A low‐temperature and easily scalable strategy for synthesizing Bi2Te3 nanostring hierarchical structures through solution‐phase reactions, during which there is the conversion of “homo–hetero–homo” in Bi2Te3 heteroepitaxial growth, is reported. Bi2Te3 nanostrings are obtained through the transformation from pure Bi2Te3 hexagonal nanosheets followed by Te?Bi2Te3 “nanotop” heterostructures to Bi2Te3 nanostrings. The growth of Bi2Te3 nanostrings appears to be a self‐assembly process through a wavy competition process generated from Te and Bi3+. The conversion of homo–hetero–homo opens up new platforms to investigate the wet chemistry of Bi2Te3 nanomaterials. Furthermore, to study the effect of morphologies and hetero/homo structures, especially with the same origin and uniform conditions on their thermoelectric properties, the thermoelectric properties of Bi2Te3 nanostrings and Te?Bi2Te3 heterostructured pellets fabricated by spark plasma sintering have been investigated separately. 相似文献
3.
Creating Zipper‐Like van der Waals Gap Discontinuity in Low‐Temperature‐Processed Nanostructured PbBi2nTe1+3n: Enhanced Phonon Scattering and Improved Thermoelectric Performance
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Prof. Dr. Biao Xu Dr. Tianli Feng Zhe Li Prof. Dr. Lin Zhou Prof. Dr. Sokrates T. Pantelides Prof. Dr. Yue Wu 《Angewandte Chemie (International ed. in English)》2018,57(34):10938-10943
Nanoengineered materials can embody distinct atomic structures which deviate from that of the bulk‐grain counterpart and induce significantly modified electronic structures and physical/chemical properties. The phonon structure and thermal properties, which can also be potentially modulated by the modified atomic structure in nanostructured materials, however, are seldom investigated. Employed here is a mild approach to fabricate nanostructured PbBi2nTe1+3n using a solution‐synthesized PbTe‐Bi2Te3 nano‐heterostructure as a precursor. The as‐obtained monoliths have unprecedented atomic structure, differing from that of the bulk counterpart, especially the zipper‐like van der Waals gap discontinuity and the random arrangement of septuple‐quintuple layers. These structural motifs break the lattice periodicity and coherence of phonon transport, leading to ultralow thermal conductivity and excellent thermoelectric z T. 相似文献
4.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(13):3600-3605
To enhance the performance of thermoelectric materials and enable access to their widespread applications, it is beneficial yet challenging to synthesize hollow nanostructures in large quantities, with high porosity, low thermal conductivity (κ ) and excellent figure of merit (z T ). Herein we report a scalable (ca. 11.0 g per batch) and low‐temperature colloidal processing route for Bi2Te2.5Se0.5 hollow nanostructures. They are sintered into porous, bulk nanocomposites (phi 10 mm×h 10 mm) with low κ (0.48 W m−1 K−1) and the highest z T (1.18) among state‐of‐the‐art Bi2Te3−x Sex materilas. Additional benefits of the unprecedented low relative density (68–77 %) are the large demand reduction of raw materials and the improved portability. This method can be adopted to fabricate other porous phase‐transition and thermoelectric chalcogenide materials and will pave the way for the implementation of hollow nanostructures in other fields. 相似文献
5.
Thermal Stability,Microstructure and Photocatalytic Activity of the Bismuth Oxybromide Photocatalyst
Flake BiOBr was first prepared by a solution method at room temperature. Then, the produced BiOBr was calcined at different temperatures. It was found that BiOBr is not a stable compound. It transforms to plate‐like Bi24O31Br11at around 750°C and the formed Bi24O31Br11 can further convert to rod‐like α‐Bi2O3 at around 850°C. The prepared compounds were characterized with X‐ray diffraction (XRD), N2 physical adsorption, scanning electron microscopy (SEM), and UV‐Vis diffuse reflectance spectra (DRS), respectively. The photocatalytic activity of the produced bismuth oxybromides was evaluated by photocatalytic decomposition of acid orange II under both visible light (λ>420 nm) and UV light (λ=365 nm) irradiation. Results show that these compounds have different band gaps and different photocatalytic properties. The band gap energies of the as‐prepared samples were found to be 2.82, 2.79, 2.60 and 3.15 eV for BiOBr, BiOBr/Bi24O31Br, Bi24O31Br, and α‐Bi2O3, respectively. Under both UV light and visible light irradiation, the photocatalytic activity follows the order: BiOBr/Bi24O31Br mixture>BiOBr>Bi24O31Br>α‐Bi2O3. The change in photocatalytic activity could be attributed to the different light absorption ability and microstructures of the photocatalysts. 相似文献
6.
The Influence of Nanoscale Heterostructures on the Thermoelectric Properties of Bi‐substituted Tl5Te3
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Frank Heinke Lucien Eisenburger Robert Schlegel Stefan Schwarzmüller Oliver Oeckler 《无机化学与普通化学杂志》2017,643(6):447-454
Tl4.5Bi0.5Te3 crystallizes in a distorted variant of the Tl5Te3 structure type in the space group I4/m. The symmetry reduction compared to Tl5Te3 (space group I4/mcm) is a consequence of cation ordering as shown by resonant X‐ray scattering using synchrotron radiation. Tl and Bi predominantly occupy one Wyckoff site each. This ordering is accompanied by displacements of Te atoms. The influence of nanostructuring on the thermoelectric performance of Tl4.5Bi0.5Te3 was investigated for the new composite model system Tl4.5Bi0.5Te3 – TlInTe2. For the nominal composition (Tl4.5Bi0.5Te3)0.6(TlInTe2)0.4, the thermoelectric Figure of merit ZT reaches 0.8 at 325 °C. Nanoscaled precipitates with sizes of about 100–200 nm probably have beneficial influence on the thermal conductivity at this temperature. 相似文献
7.
Polymeric, Band Shaped Tellurium Cations in the Structures of the Chloroberyllate Te7[Be2Cl6] and the Chlorobismutate (Te4)(Te10)[Bi4Cl16] Te7[Be2Cl6] is obtained at 250 °C in an eutectic Na2[BeCl4] / BeCl2 melt from Te, TeCl4 und BeCl2 in form of black crystals, which are sensitive towards hydrolysis in moist air. (Te4) (Te10)[Bi4Cl16] is prepared from Te, TeCl4 und BiCl3 by chemical vapour transport in sealed evacuated glass ampoules in a temperature gradient 150 ° → 90 °Cin form of needle shaped crystals with a silver lustre. The structures of both compounds were determined based on single crystal X‐ray diffraction data (Te7[Be2Cl6]: orthorhombic, Pnnm, Z = 2, a = 541.60(3), b = 974.79(6), c = 1664.4(1) pm; (Te4)(Te10)[Bi4Cl16]: triclinic, P1¯, Z = 2, a = 547.2(3), b = 1321.1(7), c = 1490(1) pm, α = 102.09(5)°, β = 95.05(5)°, γ = 96.69(4)°). The structure of Te7[Be2Cl6] consists of one‐dimensional polymeric cations (Te72+)n which form folded bands and of discrete [Be2Cl6]2— anions which form double tetrahedraconnected by a common edge. By a different way of folding compared with the cations present in the structures of Te7[MOX4]X (M = Nb, W; X = Cl, Br) the (Te72+)n cation in Te7[Be2Cl6]represents a new, isomeric form. The structure of (Te4)(Te10)[Bi4Cl16] contains two different polymeric cations. (Te102+)n consists of planar Te10 groups in the form of three corner‐sharing Te4 rings connected to folded bands. (Te42+)n forms in contrast to the so far notoriously observed discrete, square‐planar E42+ ions a chain of rectangular planar Te4 rings (Te—Te 274 and 281 pm) connected by Te‐Te bonds of 297 pm. [Bi4Cl16]4— has a complex one‐dimensional structure of edge‐ and corner‐sharing BiCl7 units. 相似文献
8.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(46):14753-14758
Creation of new van der Waals heterostructures by stacking different two dimensional (2D) crystals on top of each other in a chosen sequence is the next challenge after the discovery of graphene, mono/few layer of h ‐BN, and transition‐metal dichalcogenides. However, chemical syntheses of van der Waals heterostructures are rarer than the physical preparation techniques. Herein, we demonstrate the kinetic stabilization of 2D ultrathin heterostructure (ca. 1.13–2.35 nm thick) nanosheets of layered intergrowth SnBi2Te4, SnBi4Te7, and SnBi6Te10, which belong to the Snm Bi2n Te3n +m homologous series, by a simple solution based synthesis. Few‐layer nanosheets exhibit ultralow lattice thermal conductivity (κ lat) of 0.3–0.5 W m−1 K−1 and semiconducting electron‐transport properties with high carrier mobility. 相似文献
9.
《化学:亚洲杂志》2017,12(20):2734-2743
We explored garnet‐structured oxide materials containing 3d transition‐metal ions (e.g., Co2+, Ni2+, Cu2+, and Fe3+) for the development of new inorganic colored materials. For this purpose, we synthesized new garnets, Ca3Sb2Ga2ZnO12 ( I ) and Ca3Sb2Fe2ZnO12 ( II ), that were isostructural with Ca3Te2Zn3O12. Substitution of Co2+, Ni2+, and Cu2+ at the tetrahedral Zn2+ sites in I and II gave rise to brilliantly colored materials (different shades of blue, green, turquoise, and red). The materials were characterized by optical absorption spectroscopy and CIE chromaticity diagrams. The Fe3+‐containing oxides showed band‐gap narrowing (owing to strong sp–d exchange interactions between Zn2+ and the transition‐metal ion), and this tuned the color of these materials uniquely. We also characterized the color and optical absorption properties of Ca3Te2Zn3−x Cox O12 (0<x ≤2.0) and Cd3Te2Zn3−x Cox O12 (0<x ≤1.0), which display brilliant blue and green‐blue colors, respectively. The present work brings out the role of the distorted tetrahedral coordination geometry of transition‐metal ions and ligand–metal charge transfer (which is manifested as narrowing of the band gap) in producing brilliantly colored garnet‐based materials. 相似文献
10.
Dr. Guanjun Xiao Dr. Chunye Zhu Prof. Yanming Ma Prof. Bingbing Liu Prof. Guangtian Zou Prof. Bo Zou 《Angewandte Chemie (International ed. in English)》2014,53(3):729-733
There is an urgent need for the development in the field of the magnetism of topological insulators, owing to the necessity for the realization of the quantum anomalous Hall effect. Herein, we discuss experimentally fabricated nanostructured hierarchical architectures of the topological insulator Bi2Te3 without the introduction of any exotic magnetic dopants, in which intriguing room‐temperature ferromagnetism was identified. First‐principles calculations demonstrated that the intrinsic point defect with respect to the antisite Te site is responsible for the creation of a magnetic moment. Such a mechanism, which is different from that of a vacancy defect, provides new insights into the origins of magnetism. Our findings may pave the way for developing future Bi2Te3‐based dissipationless spintronics and fault‐tolerant quantum computation. 相似文献
11.
Heterocyclic Bismuth(III) Dithiocarbamato Complexes as Single‐Source Precursors for the Synthesis of Anisotropic Bi2S3 Nanoparticles
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Walter N. Kun Dr. Sixberth Mlowe Dr. Linda D. Nyamen Prof. Peter T. Ndifon Dr. Mohammad A. Malik Prof. Orde Q. Munro Prof. Neerish Revaprasadu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(37):13127-13135
New complexes catena‐(μ2‐nitrato‐O,O′)bis(piperidinedithiocarbamato)bismuth(III) ( 1 ) and tetrakis(μ‐nitrato)tetrakis[bis(tetrahydroquinolinedithiocarbamato)bismuth(III)] ( 2 ) were synthesised and characterised by elemental analysis, FTIR spectroscopy and thermogravimetric analysis. The single‐crystal X‐ray structures of 1 and 2 were determined. The coordination numbers of the BiIII ion are 8 for 1 and ≥6 for 2 when the experimental electron density for the nominal 6s2 lone pair of electrons is included. Both complexes were used as single‐source precursors for the synthesis of dodecylamine‐, hexadecylamine‐, oleylamine and tri‐n‐octylphosphine oxide‐capped Bi2S3 nanoparticles at different temperatures. UV/Vis spectra showed a blueshift in the absorbance band edge characteristic of a quantum size effect. High‐quality, crystalline, long and short Bi2S3 nanorods were obtained depending on the thermolysis temperature, which was varied from 190 to 270 °C. A general trend of increasing particle breadth with increasing reaction temperature and increasing length of the carbon chain of the amine (capping agent) was observed. Powder XRD patterns revealed the orthorhombic crystal structure of Bi2S3. 相似文献
12.
Deep‐Level Defect Enhanced Photothermal Performance of Bismuth Sulfide–Gold Heterojunction Nanorods for Photothermal Therapy of Cancer Guided by Computed Tomography Imaging
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Dr. Yan Cheng Yun Chang Yanlin Feng Hui Jian Prof. Zhaohui Tang Prof. Haiyuan Zhang 《Angewandte Chemie (International ed. in English)》2018,57(1):246-251
Bismuth sulfide (Bi2S3) nanomaterials are emerging as a promising theranostic platform for computed tomography imaging and photothermal therapy of cancer. Herein, the photothermal properties of Bi2S3 nanorods (NRs) were unveiled to intensely correlate to their intrinsic deep‐level defects (DLDs) that potentially could work as electron–hole nonradiative recombination centers to promote phonon production, ultimately leading to photothermal performance. Bi2S3‐Au heterojunction NRs were designed to hold more significant DLD properties, exhibiting more potent photothermal performance than Bi2S3 NRs. Under 808 nm laser irradiation, Bi2S3‐Au NRs could trigger higher cellular heat shock protein 70 expression and more apoptotic cells than Bi2S3 NRs, and caused severe cell death and tumor growth inhibition, showing great potential for photothermal therapy of cancer guided by computed tomography imaging. 相似文献
13.
14.
Chemical and physical reactions during the low temperature aqueous chemical synthesis of nanostructured Bi2Te3 powders were investigated in-situ by pH measurement, color observation of the solution and X-ray diffraction analysis of
the powders. It was found that Bi2Te3 could be synthesized only in a strong alkaline solution. Bi2Te3 nanocapsules were synthesized by the aqueous chemical route at 65 °C with the addition of disodium ethylenediaminetetraacetate
salt. High-resolution transmission electron microscopy observation indicates that the nanocapsules are hollow-structured with
a wall thickness of about 6 nm.
__________
Translated from CHIMICA SINICA, 2005, 63(16)(in Chinese) 相似文献
15.
Bi2Te3 nanoparticles (NPs) have been synthesized at 50?°C by a low-cost wet chemical route. The structural properties of product sample were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy. Thermal properties of product sample were investigated by differential scanning calorimetry (DSC), thermogravimetric (TG), and transient plane source techniques. The XRD and selected area electron diffraction of Bi2Te3 NPs result showed the polycrystalline nature with a rhombohedral (R3m) structure of the nanocrystallites. The average grain size of Bi2Te3 NPs was found to be about 30?nm by XRD and TEM measurements. DSC result shows one endothermic peak and one exothermic peak. TG result shows that only 48?% mass loss has occurred in Bi2Te3 sample. The obtained lower thermal conductivity of Bi2Te3 NPs is about 0.3?W m?1 K?1 at room temperature, which is caused by considering the crystalline nature of this material. 相似文献
16.
J.L. Cui W.J. Xiu L.D. Mao P.Z. Ying X. Qian 《Journal of solid state chemistry》2007,180(3):1158-1162
Ag-doped n-type (Bi2Te3)0.9-(Bi2−xAgxSe3)0.1 (x=0-0.4) alloys were prepared by spark plasma sintering and their physical properties evaluated. When at low Ag content (x=0.05), the temperature dependence of the lattice thermal conductivity follows the trend of (Bi2Te3)0.9-(Bi2Se3)0.1; while at higher Ag content, a relatively rapid reduction above 400 K can be observed due possibly to the enhancement of scattering of phonons by the increased defects. The Seebeck coefficient increases with Ag content, with some loss of electrical conductivity, but the maximum dimensionless figure of merit ZT can be obtained to be 0.86 for the alloy with x=0.4 at 505 K, about 0.2 higher than that of the alloy (Bi2Te3)0.9-(Bi2Se3)0.1 without Ag-doping. 相似文献
17.
Concerted Rattling in CsAg5Te3 Leading to Ultralow Thermal Conductivity and High Thermoelectric Performance
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Dr. Hua Lin Dr. Gangjian Tan Dr. Jin‐Ni Shen Dr. Shiqiang Hao Prof. Li‐Ming Wu Dr. Nicholas Calta Dr. Christos Malliakas Si Wang Prof. Ctirad Uher Prof. Christopher Wolverton Prof. Mercouri G. Kanatzidis 《Angewandte Chemie (International ed. in English)》2016,55(38):11431-11436
Thermoelectric (TE) materials convert heat energy directly into electricity, and introducing new materials with high conversion efficiency is a great challenge because of the rare combination of interdependent electrical and thermal transport properties required to be present in a single material. The TE efficiency is defined by the figure of merit ZT=(S2σ) T/κ, where S is the Seebeck coefficient, σ is the electrical conductivity, κ is the total thermal conductivity, and T is the absolute temperature. A new p‐type thermoelectric material, CsAg5Te3, is presented that exhibits ultralow lattice thermal conductivity (ca. 0.18 Wm?1 K?1) and a high figure of merit of about 1.5 at 727 K. The lattice thermal conductivity is the lowest among state‐of‐the‐art thermoelectrics; it is attributed to a previously unrecognized phonon scattering mechanism that involves the concerted rattling of a group of Ag ions that strongly raises the Grüneisen parameters of the material. 相似文献
18.
The valence band (VB) density of states and the binding energies of the weakly bound core levels have been measured by XUV photoelectron spectroscopy using synchrotron radiation for four V–VI layered compounds. Chemical shifts of the core levels are determined which support the partial ionicity of the bonds involved. The chemical shifts of the emission from two unequivalent crystal sites were shown to differ by less than 30 meV for the compounds Bi2Te3, Bi2Se3 and Sb2Te3.VB and core-level photoemission spectra for the V–VI compounds Bi2Te3, Bi2Se3, Sb2Te3 and Se2Te2Se have been presented. Chemical shifts of the Te 4d, Bi 5d, Sb 4d and Se 3d levels were determined, indicating partial ionicity of the mainly covalent bonds involved. Chemical-shift differences originating from atoms at two different crystal sites are <30 meV. In a simple model this implies that similar charge transfers do occur even though completely different bond orbitals were proposed for the and the AB(2) bonds. Finally, the fact that no surface core-level shifts were observed tends to confirm the very weak influence of the van der Waals-like bonds on the B(2) atoms. 相似文献
19.
Dr. Fei Jia Xin Yin Wen-Wen Cheng Jia-Ting Lan Shu-Hui Zhan Prof. Dr. Ling Chen Prof. Dr. Li-Ming Wu 《Angewandte Chemie (International ed. in English)》2023,62(15):e202218019
Room-temperature thermoelectric materials are the key to miniaturizing refrigeration equipment and have great scientific and social implications, yet their application is hindered by their extreme scarcity. BiTe exhibiting strong spin-orbit coupling peaks ZT at 600 K. Herein, we discover the synergy effect of Sb doping in BiTe that eliminates the detrimental band inversion and leads to an overlap of conduction band (CB) and valence band that significantly increases the S from 33 to 124 μV K−1. In addition, this effect enhances the μ from 58 to 92 cm2 V−1 s−1 owing to the sharp increase in the CB slope along the Γ-A in the first Brillouin zone. Furthermore, Sb doping increases the anharmonicity, shortens the phonon lifetime and lowers κlat. Finally, Se/Sb codoping further optimizes the ZT to 0.6 at 300 K, suggesting that Bi0.6Sb0.4Te1−ySey is a potential room-temperature TE material. 相似文献
20.
G. R. Gurbanov I. B. Bakhtiyarly R. D. Kurbanova 《Russian Journal of Inorganic Chemistry》2010,55(7):1149-1152
This is the first study of the SnSbBiTe4-2Bi2Te3 join of the SnTe-Bi2Te3-Sb2Te3 quasi-ternary system by the methods of complex physicochemical analysis over a wide range of concentrations. A phase diagram
was constructed for the title quasi-binary join. The system was found to be of the eutectic type; the eutectic coordinates
are 65 mol % Bi2Te3 and 675 K. The starting components were shown to form solid solutions with extents of 20 mol %. Alloys with compositions
lying within the Bi2Te3-based solid solution region were found to be n-type semiconductors. 相似文献