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Ambient surface stability of thin film nanocrystalline Cu <sub/>3</sub> SbSe <sub/>4</sub> and structure-property relationships
摘要： Nanocrystalline materials have a high surface area, and hence may be significantly more reactive than their bulk counterparts under ambient conditions. This may affect device function in unexpected ways. Here, high quality crystalline Cu3SbSe4 nanocrystals are synthesized through a hot injection route, and thin films are deposited through a ligand exchange procedure. The electronic conductivity of the films increases significantly upon exposure to air, up to 80 Ω-1cm-1. This increase in conductivity is correlated to a surface oxidation as observed by XPS. The observed changes in the film upon exposure to ambient conditions are suggested to be critical for understanding the properties of these materials as they are incorporated into devices.
关键词： surface oxidation,earth abundant,copper antimony chalcogenides,hot injection,Thermoelectrics,nanoparticles
更新于2025-11-14 15:19:41
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The <i>h</i> -Sb <sub/>x</sub> WO <sub/> 3+2 <i>x</i> </sub> Oxygen Excess Antimony Tungsten Bronze
摘要： The previously unreported oxygen excess hexagonal antimony tungsten bronze is reported, with a composition of Sb0.5W3O10, in the following denoted as h-SbxWO3 + 2x with x = 0.167, to demonstrate its analogy to classical AxWO3 tungsten bronzes. This compound forms in a relatively narrow temperature range between 580 8C < T < 620 8C. It was obtained as a dark-blue polycrystalline powder, and as thin, needle-shaped, blue single crystals. h-SbxWO3 + 2x crystallizes in the hexagonal space group P6/mmm with the cell parameters a = 7.4369(4) (cid:2) and c = 3.7800(2) (cid:2). The antimony and excess oxygen occupy the hexagonal channels within the network of corner-sharing WO6 octahedra. h-SbxWO3 + 2x has a resistivity of 1300 K (cid:2) 1.28 mW cm at room temperature, with little if any temperature-dependence on cooling. DFT calculations on a simplified model for this compound find a metallic-like electronic structure with the Fermi level falling within rather flat bands, especially around the G point.
关键词： hexagonal bipyramids,metallic oxide,tungsten,antimony,bronze
更新于2025-09-23 15:23:52
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Optimal synthesis of antimony-doped cuprous oxides for photoelectrochemical applications
摘要： We investigated the influence of Sb dopant concentration on the structural, electrical, and photoelectrochemical properties of the photocathode cuprous oxide (Cu2O) thin films. The photoabsorber p-type Cu2O films were prepared by electrodeposition in ionic electrolytes including copper sulfate and antimony sulfate at 333 K and pH=10. The small amount of Sb doping contributes to the fast Cu ion transport to the substrate and ion consumption; consequently, the p-type Cu2O with high crystalline quality can be reproducibly synthesized with high electrical stability. Among the various samples, the mole fraction of c(Sb)/[c(Cu)+c(Sb)] = 0.75 mol % exhibits the best electrical resistivity and improved transparency in the infrared region, which is involved with the fast overlap of the nuclei crystals under 5 nm from the high nuclei density. Additionally, the post-thermal annealed Sb-doped Cu2O sample reveals an enhanced photocurrent of ~0.65 mA/cm2 vs. RHE (reversible hydrogen electrode) without metal catalysts.
关键词： Preferred orientation,Post annealing,Antimony doping,Photoelectrochemical cell,Cuprous oxide
更新于2025-09-23 15:23:52
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Ab initio calculation of antimony sulphide nanowire
摘要： We have performed first-principles calculations on orthorhombic antimony sulphide (Sb2S3) nanowire using full-potential linearized augmented plane wave (FP-LAPW) method based on the density-functional theory (DFT) as implemented in WIEN2k package to investigate the electronic and optical properties. Engel–Vosko generalized gradient approximation (EV-GGA) is used as exchange-correlation functional. The nanowire is simulated in the [001] direction with vacuum in two directions using supercell method. The results are compared with Sb2S3 bulk in our pervious calculation. We have found that the electronic and optical properties significantly change in Sb2S3 nanowire. The density of state (DOS) for Sb2S3 nanowire calculated is higher than bulk Sb2S3 and from the electronic band structure, the indirect band gap is about 0.12 eV where this value is much lower than Sb2S3 bulk. However, this value is much lower than experimental value. The optical properties including absorption coefficient, reflectivity, refractive index and energy loss function are derived from the calculated complex dielectric for photon energy up to 20 eV to understand the optical behavior of Sb2S3 in one-dimensional (1-D) nanostructure. From analysis, the optical response of Sb2S3 nanowire demonstrate quite interesting optical behavior for one-dimension (1-D) nanostructure. The absorption coefficient for Sb2S3 nanowire is considerably higher in visible light range than Sb2S3 bulk.
关键词： optical properties,Antimony Sulphide,Density Functional Theory,LAPW,nanowire,electronic structure
更新于2025-09-23 15:23:52
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Rare Earth Doping of Topological Insulators: A Brief Review of Thin Film and Heterostructure Systems
摘要： Magnetic topological insulators (MTIs) are a novel materials class in which a topologically nontrivial electronic band structure coexists with long-range ferromagnetic order. The ferromagnetic ground state can break time-reversal symmetry, opening a gap in the topological surface states whose size is dependent on the magnitude of the magnetic moment. Doping with rare earth ions is one way to introduce higher magnetic moments into a material, however, in Bi2Te3 bulk crystals, the solubility limit is only a few percent. Using molecular beam epitaxy for the growth of doped (Sb,Bi)2(Se,Te)3 TI thin films, high doping concentrations can be achieved while preserving their high crystalline quality. The growth, structural, electronic, and magnetic properties of Dy, Ho, and Gd doped TI thin films will be reviewed. Indeed, high magnetic moments can be introduced into the TIs, which are, however, not ferromagnetically ordered. By making use of interfacial effects, magnetic long-range order in Dy doped Bi2Te3, proximity-coupled to the MTI Cr:Sb2Te3, has been achieved. Clearly, engineered MTI heterostructures offer new possibilities that combine the advantageous properties of different layers, and thus provide an ideal materials platform enabling the observation new quantum effects at higher temperatures.
关键词： rare earth doping,MBE,topological insulators,heterostructure,bismuth telluride,antimony telluride
更新于2025-09-23 15:22:29
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Uniform Sb <sub/>2</sub> S <sub/>3</sub> optical coatings by chemical spray method
摘要： Antimony sulfide (Sb2S3), an environmentally benign material, has been prepared by various deposition methods for use as a solar absorber due to its direct band gap of ≈1.7 eV and high absorption coefficient in the visible light spectrum (1.8 × 105 cm?1 at 450 nm). Rapid, scalable, economically viable and controllable in-air growth of continuous, uniform, polycrystalline Sb2S3 absorber layers has not yet been accomplished. This could be achieved with chemical spray pyrolysis, a robust chemical method for deposition of thin films. We applied a two-stage process to produce continuous Sb2S3 optical coatings with uniform thickness. First, amorphous Sb2S3 layers, likely forming by 3D Volmer–Weber island growth through a molten phase reaction between SbCl3 and SC(NH2)2, were deposited in air on a glass/ITO/TiO2 substrate by ultrasonic spraying of methanolic Sb/S 1:3 molar ratio solution at 200–210 °C. Second, we produced polycrystalline uniform films of Sb2S3 (Eg 1.8 eV) with a post-deposition thermal treatment of amorphous Sb2S3 layers in vacuum at 170 °C, <4 × 10?6 Torr for 5 minutes. The effects of the deposition temperature, the precursor molar ratio and the thermal treatment temperature on the Sb2S3 layers were investigated using Raman spectroscopy, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and UV–vis–NIR spectroscopy. We demonstrated that Sb2S3 optical coatings with controllable structure, morphology and optical properties can be deposited by ultrasonic spray pyrolysis in air by tuning of the deposition temperature, the Sb/S precursor molar ratio in the spray solution, and the post-deposition treatment temperature.
关键词： vacuum annealing,Volmer–Weber growth,antimony sulfide,thin films,ultrasonic spray
更新于2025-09-23 15:22:29
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Sb <sub/>2</sub> Te <sub/>3</sub> growth study reveals: Formation of Nanoscale Charge Carrier Domains Is an Intrinsic Feature Relevant for Electronic Applications
摘要： Sb2Te3 exhibits a plethora of fundamentally relevant electronic phenomena enabling electronic phase change memory cells, thermoelectric devices and three-dimensional topological insulator structures. Thus, the controlled growth of nanostructures and thin films with well-defined electronic properties is of uttermost importance. Previously, our group observed symmetric infrared domains in hexagonal Sb2Te3 nanoplatelets from a solvothermal chemical synthesis. The relative optical contrast observed was indirectly linked to the formation of regions with different defect densities (charge carrier concentrations). This raises two major questions, which we answer in this study: Is the domain formation restricted to the specific platelet growth process? No! Do the infrared spectra of both domains really follow a ‘Drude-like’ free charge carrier response? Yes! By controlling the initial water concentration, we promote the growth of the nanoplatelets in c-direction and tune the morphology from platelet-like to octahedra-like. Although the growth mode changes from spiral growth to layer-by-layer, similar infrared domains are identified using scattering-type scanning near-field optical microscopy (s-SNOM). Furthermore, we also reproduced the formation of symmetric infrared domains in thin, high quality crystalline films grown using molecular beam epitaxy (MBE). Normalized infrared near-field spectra of smaller Sb2Te3 nanoparticles reveal a relative shift of the plasma frequency in both domains. These findings demonstrate that the formation of domains with different charge carrier properties is an intrinsic material property of Sb2Te3 and might strongly influence all of its electronic applications.
关键词： infrared near-field microscopy,Antimony telluride,domain formation,van der Waals materials,transition metal dichalcogenides,epitaxial growth
更新于2025-09-23 15:21:21
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Humidity sensing characteristics of Sb2O3 thin films with transitional electrical behavior
摘要： The quest for smaller and more efficient humidity sensors is still on. Antimony trioxide thin films deposited by vacuum thermal evaporation onto heated glass substrates are analyzed as water vapor sensors, along with the study of their morpho-structural and electrical properties. Several substrate temperatures were set during the depositions, leading to films with significantly different electrical and humidity sensing features. Unusual increase of the electrical resistance of the films with temperature above 170 ?C was noticed, representing the intermediate stage between extrinsic and intrinsic conductivity. In the extrinsic conduction region, the activation energy decreases exponentially with the substrate temperature during the initial depositions. The alternative current (AC), i.e. the electrical frequency characteristics versus humidity were also studied, allowing for the identification of the conduction mechanism within the samples, which is most probably short range hopping of charge carriers through trap sites, influences by the changing grain size and remanent amorphous phase within the films.
关键词： Activation energy,Humidity sensitivity,Antimony trioxide,Thin films,Frequency characteristics
更新于2025-09-23 15:21:21
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Formation of stable 2D methylammonium antimony iodide phase for lead-free perovskite-like solar cells
摘要： The presence of lead in novel hybrid perovskite-based solar cells remains a significant issue regarding commercial applications. Therefore, antimony-based perovskite-like A3M2X9 structures are promising new candidates for low toxicity photovoltaic applications. So far, MA3Sb2I9 was reported to only crystallize in the ‘zero-dimensional’ (0D) dimer structure with wide indirect bandgap properties. However, the formation of the 2D layered polymorph is more suitable for solar cell applications due to its expected direct and narrow bandgap. Here, we demonstrate the first synthesis of phase pure 2D layered MA3Sb2I9, based on antimony acetate dissolved in alcoholic solvents. Using in situ XRD methods, we confirm the stability of the layered phase towards high temperature, but the exposure to 75 % relative humidity for several hours leads to a rearrangement of the phase with partial formation of the 0D structure. We investigated the electronic band structure and confirmed experimentally the presence of a semi-direct bandgap at around 2.1 eV. Our work shows that careful control of nucleation via processing conditions can provide access to promising perovskite-like phases for photovoltaic applications.
关键词： antimony,perovskite solar cells,2D materials,lead-free,photovoltaic applications
更新于2025-09-23 15:21:01
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Synthesis and characterization of Sb doped SnO<sub>2</sub> for the photovoltaic applications: different route
摘要： Antimony doped tin oxide (ATO - Sn0.92O2:Sb0.08) nanoparticles were synthesized by different chemical routes such as Hydrothermal (HT), Sol-gel (SG) and Sonochemical (SC) methods. The XRD pattern of the samples shows that Sb ion successfully incorporated into Sn lattice without altering the crystal structure. Optical spectral analysis of the samples indicates more absorption in the visible region. The vibrational modes of the ATO nanoparticles were characterized by FTIR spectra. DSSCs were fabricated with the as-prepared ATO nanoparticles from different routes, Eosin-Y dye, I-/I3- redox couple as electrolyte. I-V characteristics of the as fabricated devices were recorded to estimate the efficiency of the device. Our results indicate the DSSC fabricated using the hydrothermally prepared material is to be considered as a suitable optical window material for dye and good electrolyte to achieve higher open circuit voltage (VOC). Further, the anode fabricated using the hydrothermally synthesized ATO nanoparticle gives good efficiency (η = 4.15%) comparing to the DSSCs fabricated using NPs synthesized via other methods. Hence, hydrothermally prepared material is to be considered as a suitable optical window materials for DSSCs.
关键词： antimony doped tin oxide,Dye sensitized solar cell,optical window
更新于2025-09-23 15:21:01