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Two-dimensional films comprising of Bi clusters ranging in size from 25 to 100 Angstrom show an influence of the underlying matrix on normal state resistivity and the superconducting transition temperature T-c. This is in contrast...
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Two-dimensional films comprising of Bi clusters ranging in size from 25 to 100 Angstrom show an influence of the underlying matrix on normal state resistivity and the superconducting transition temperature T-c. This is in contrast to crystalline Bi. Quantum size effects are observed by changing the deposition temperature, which determines the cluster size. These observations can be attributed to superconductivity at the surface. Implications for the requirement of a critical number of superconducting clusters before the establishment of global phase coherence are briefly discussed. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 14]
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An interconnected needle-like structure of Bi2O3 has been directly grown on stainless steel (SS) substrate by binder-free successive ionic layer adsorption and reaction (SILAR) method. The structural study confirms the formation o...
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An interconnected needle-like structure of Bi2O3 has been directly grown on stainless steel (SS) substrate by binder-free successive ionic layer adsorption and reaction (SILAR) method. The structural study confirms the formation of cubic delta-Bi2O3 phase. The coverage of interconnected needle-like network structure has been seen from surface morphological study. The electrochemical performance of Bi2O3 has been tested as an electrode material through cyclic voltammetry, charge-discharge, and electrochemical impedance spectroscopy techniques in aqueous electrolyte. The electrochemical tests manifest the pseudocapacitive behavior of Bi2O3 thin-film electrode with a specific capacitance of 329.6 F g(-1) at 5 mV s(-1) scan rate. In addition, the Bi2O3 electrode exhibits long-term cycling performance with 72% capacitance retention after 3000 cycles.
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Bi2VO5.5/Bi2O3 laminated composite thin films with each different layer numbers were prepared on fused silica substrates by chemical solution deposition method with a following rapid annealing process. The phase structure, surface...
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Bi2VO5.5/Bi2O3 laminated composite thin films with each different layer numbers were prepared on fused silica substrates by chemical solution deposition method with a following rapid annealing process. The phase structure, surface morphology, absorption spectrum and photocatalytic degradation characteristics of the thin films were characterized. X-ray diffraction patterns show that the laminated thin films are consist of polycrystalline Bi2O3 films and c-axis oriented Bi2VO5.5 films. With the increasing of the number of Bi2VO5.5 layers as well as the decrease of the number of Bi2O3 layers, the absorption spectrum of the composite film shifted towards the longer wavelength side. Meanwhile, under simulated sunlight, the degradation ability of the thin films to Methylene Blue gradually increased and reach a maximum at appropriate layer ratio. The optimal laminated composite thin film with the highest degradation rate are 6 layers of Bi2VO5.5 films superposed upon 2 layers of Bi2O3 films. The degradation rate decreases only by 2% after the 5 cycles of degradation. The reasons for the enhancement of the photocatalytic properties of the thin film can be attribute to the laminated structure and the matching energy level, which are benefit for the transferring of photo-induced electrons. According to fitting results of the band gap and the XPS valence band spectrum, the mechanism of photocatalytic degradation of MB for Bi2VO5.5/Bi2O3 laminated composite films irradiation are analyzed. Under simulated sunlight irradiation, the photogenerated electrons on the conduction band of the Bi2O3 can transfer to the conduction band of Bi2VO5.5 Meanwhile, the photogenerated holes on the valence band of Bi2VO5.5 can also be migrated to the valence band of Bi2O3, thus suppress the recombination, prolong the lifetime of photo-generated carriers, and increase the photocatalytic degradation efficiency.
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Bi2S3 thin film electrode has been synthesized by simple and low cost successive ionic layer adsorption and reaction (SILAR) method on stainless steel (SS) substrate at room temperature. The formation of interconnected nanoparticl...
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Bi2S3 thin film electrode has been synthesized by simple and low cost successive ionic layer adsorption and reaction (SILAR) method on stainless steel (SS) substrate at room temperature. The formation of interconnected nanoparticles with nanoporous surface morphology has been achieved and which is favourable to the supercapacitor applications. Electrochemical supercapacitive performance of Bi2S3 thin film electrode has been performed through cyclic voltammetry, charge-discharge and stability studies in aqueous Na2SO4 electrolyte. The Bi2S3 thin film electrode exhibits the specific capacitance of 289 Fg(-1) at 5 mVs(-1) scan rate in 1 M Na2SO4 electrolyte.
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We report an experimental study of quench condensed (2 K less than or equal to T less than or equal to 15 K) disordered ultrathin films of Bi where localization effects and superconductivity compete. Experiments are done with diff...
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We report an experimental study of quench condensed (2 K less than or equal to T less than or equal to 15 K) disordered ultrathin films of Bi where localization effects and superconductivity compete. Experiments are done with different substrates and/or different underlayers. Quasi-free-standing films of Bi, prepared by quenching Bi vapours onto solid Xe, are also studied. The results show a dependence of the transport properties both on the dielectric constant of the substrate/underlayer as well as the temperature of quench condensation. RHEED studies indicate that quantum size effects are important in these systems. Tn this paper, we try to correlate the structure of the films to the transport properties obtained. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 5]
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The Bi2212 superconducting thin films were fabricated by using the ion beam sputtering method.As a result,although the composition of Bi2212 was set point,the phase of Bi2201.Bi2212 and Bi2223 was formed.The product region of thes...
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The Bi2212 superconducting thin films were fabricated by using the ion beam sputtering method.As a result,although the composition of Bi2212 was set point,the phase of Bi2201.Bi2212 and Bi2223 was formed.The product region of these stable phases is indicated as inclined line in the direction of the right lower end from the Arrhenius plot of the substrate temperature-oxidation gas pressure,and are distributed in very small area.According to the result observing the surface of the thin film with SEM,even in case that the formed phase and the composition of the thin film agree,also it can be known that there are a number of the precipitates on the surface
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The fabrication of thermopiles suitable for thermoelectric cooling and energy generation using Bi2Te3 and Sb2Te3 as n- and p-type layers, respectively, is reported. The thin-film thermoelectric material deposition process, thin-fi...
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The fabrication of thermopiles suitable for thermoelectric cooling and energy generation using Bi2Te3 and Sb2Te3 as n- and p-type layers, respectively, is reported. The thin-film thermoelectric material deposition process, thin-film electronic characterization and device simulation is addressed.
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BiSrCaCuO thin films and specially Bi-2212 compounds were grown on (100) SrTiO3 substrates by molecular beam epitaxy (MBE). The growth mechanism was controlled in real time by monitoring the RHEED intensity. The deposition sequenc...
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BiSrCaCuO thin films and specially Bi-2212 compounds were grown on (100) SrTiO3 substrates by molecular beam epitaxy (MBE). The growth mechanism was controlled in real time by monitoring the RHEED intensity. The deposition sequence of the elements was also varied in order to induce intergrowth structures at nanometer scale. The resulting high density of stacking faults is in contrast with a very low roughness (in the range of 1 nm as measured by atomic force microscopy), a strong c-axis texturation, and a full epitaxy within the ab-plane as confirmed by four circle X-ray diffraction. The local structure of the films was examined by high resolution transmission electron microscopy (HRTEM) in correlation with the superconducting properties. Both structural and transport properties seem to be deeply affected by the percolation of 2212 domains as their concentration in the film is changed. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 35]
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Textured surface un-doped zinc oxide (ZnO) and boron-doped ZnO (ZnO:B) thin films with pyramid-like grains were directly deposited by metal organic rhemicai vapor deposition (MOCVD) technique and hydrogenated gallium-doped ZnO (HG...
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Textured surface un-doped zinc oxide (ZnO) and boron-doped ZnO (ZnO:B) thin films with pyramid-like grains were directly deposited by metal organic rhemicai vapor deposition (MOCVD) technique and hydrogenated gallium-doped ZnO (HGZO) thin films with good electrical properties were grown by pulsed direct-current magnetron sputtering. In order to obtain high quality transparent conductive oxides (TCOs) for Si-based thin film solar cells, through combining the advantages of MOCVD-ZnO and sputter-HGZO thin films, bi-layer textured surface glass/ZnO:B/HGZO and glass/HGZO/ZnO:B TCO thin films with milky surface were fabricated and investigated in detail. The main research purposes are to explore appropriate surface morphology and improve the electrical properties of TCO layers. Compared with textured surface un-doped ZnO and ZnO:B thin films, both the bi-layer ZnO/HGZO and ZnO:B/HGZO thin films exhibit high electron mobility. The ZnO:B/HGZO thin films present modified pyramid-like surface morphology with high transparencies (T> 85%) and excellent electrical properties (resistivity of-9.28×10~(-4) Ωcm and mobility of-28.8 cm~2/Vs). Meanwhile, the HGZO/ZnO thin films exhibit large grain size (-500 nm-1000 nm) with preferred growth orientations along (100) and (002) crystallographic directions. Bi-layer HGZO/ZnO and HGZO/ZnO:B thin films exhibit relatively higher diffuse transmittance than that of corresponding ZnO and ZnO:B thin films.
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AZO/IZO and IZO/AZO bi-layer thin films were deposited on the glass substrates by using pulsed laser deposition (PLD). The crystallinity and the texture of the thin film depend on the sequence of deposition of the IZO layer and th...
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AZO/IZO and IZO/AZO bi-layer thin films were deposited on the glass substrates by using pulsed laser deposition (PLD). The crystallinity and the texture of the thin film depend on the sequence of deposition of the IZO layer and the AZO layer. The crystal structures, the electrical and optical properties of the AZO/IZO and the IZO/AZO thin film were analyzed and compared using X-ray diffraction, field-emission scanning electron microscope, Hall measurements and UV spectrometry. The IZO/AZO bi-layer thin film showed a highly-oriented texture of IZO along the <111> axis, which implied that the c-axis-oriented AZO buffer layer enhanced the tendency of the IZO thin film to grow preferentially along the <111> axis. On the other hand, the AZO/IZO thin film did not revealed oriented grain growth of the AZO layer, which indicated that randomly- oriented IZO buffer layer suppressed the tendency of the AZO thin film to grow preferentially along the c-axis. The AZO/IZO and the IZO/AZO bi-layer thin films showed the average values of the AZO and the IZO monolayers for the electrical resistivity and the optical band gap.
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