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Equilibria in a ZnCl2–H2O–NaOH System, According to Data from Potentiometric Titration, and Selecting Conditions for the Hydrochemical Synthesis of ZnS and ZnSe Films
摘要： Equilibrium processes that occur in the ZnCl2–H2O–NaOH system are studied via the potentiometric titration of zinc chloride in the 0.00006–1.01 mol/L range of concentrations. Based on mathematical simulations, a number of polynuclear structures and soluble phases are identified in the system. Values of the instability constants of complex forms and the constants of the dynamic equilibria of weakly soluble zinc compounds are calculated, along with their stoichiometric compositions and areas of sustainable existence. Refined boundary conditions are determined, along with areas of the formation of ZnSe and ZnS when they are precipitated using sodium selenosulfate and thiourea, respectively. ZnSe and ZnS layers around 1000 and 200 nm thick are obtained via hydrochemical deposition on glass-ceramic substrates. Based on electron microscopy data, it is concluded that the layers consist of spherical aggregates with mean sizes of around 350–450 nm for ZnSe and 50–200 nm for ZnS, generated from primary particles with sizes of around 20–60 and 20–30 nm, respectively.
关键词： equilibrium processes,zinc selenide,complex formation,zinc sulfide,zinc chloride,potentiometric titration,thin films
更新于2025-09-04 15:30:14
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Influence of the Conditions of the Chemical Bath Deposition of Thin ZnSe Films on Their Morphology and Internal Mechanical Stresses
摘要： ZnSe films up to 2300 nm thick on glass-ceramic supports were prepared by chemical bath deposition in the ZnCl2–Na2EDTA–NaOH–NH2OH·HCl system using sodium selenosulfate as a chalcogenizer. The reflections observed in the X-ray diffraction patterns correspond to the ZnSe (stilleite) phase of cubic (space group F43m) structure with a = 5.610 ± 0.002 ?. As shown by electron-microscopic examination, ZnSe films consist of globular formations tightly adjoining to each other with the mean size of 250–400 nm depending on the deposition conditions. Elemental EDX analysis shows that the films contain, on the average, 43.68 at. % Zn, 30.50 at. % Se, and 25.82 at. % O, with the oxygen concentration somewhat decreasing at a depth of 30 nm. The internal mechanical compression stresses caused by the difference in the thermal expansion coefficients of the ZnSe film and glass-ceramic support were calculated; these stresses depend on the film thickness and at ~1040 nm reach –30.62 kN m–2. The results obtained make it possible to exclude film discontinuities, which can appear with increasing film thickness in preparation of precursor layers, and to choose the optimum support material.
关键词： chemical bath deposition,microstructure,internal mechanical stresses,film morphology,zinc selenide,films,sodium selenosulfate
更新于2025-09-04 15:30:14
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Comparative Measurements of Photoelectron Emission in Bulk Samples and Island Films of Silver
摘要： The photoelectron emission has been studied of silver island films excited by a laser pulse of 10-ns duration at three wavelengths: 355, 532, and 1064 nm. It has been shown that, for wavelengths of 355 and 532 nm, the photoemission of island films significantly differs from the photoemission of a bulk sample. For an island film, dependence on the pulse energy characteristic for single-photon emission has been observed at a 355-nm wavelength. It has also been shown that the surface plasmon resonance in nanoparticles significantly affects the photoemission and character of its dependence on the energy of the laser pulse.
关键词： laser pulse,photoelectron emission,nanoparticles,silver island films,surface plasmon resonance
更新于2025-09-04 15:30:14
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Lateral ordering of PTCDA on the clean and the oxygen pre-covered Cu(100) surface investigated by scanning tunneling microscopy and low energy electron diffraction
摘要： We have investigated the adsorption of perylene-3,4,9,10-tetracarboxylic acid dianhydride (PTCDA) on the clean and on the oxygen pre-covered Cu(100) surface [referred to as (√2 × 2√2)R45° – 2O/Cu(100)] by scanning tunneling microscopy (STM) and low energy electron diffraction (LEED). Our results confirm the (4√2 × 5√2)R45° superstructure of PTCDA/Cu(100) reported by A. Schmidt et al. [J. Phys. Chem. 1995, 99,11770–11779]. However, contrary to Schmidt et al., we have no indication for a dissociation of the PTCDA upon adsorption, and we propose a detailed structure model with two intact PTCDA molecules within the unit cell. Domains of high lateral order are obtained, if the deposition is performed at 400 K. For deposition at room temperature, a significant density of nucleation defects is found pointing to a strong interaction of PTCDA with Cu(100). Quite differently, after preadsorption of oxygen and formation of the (√2 × 2√2)R45° – 2O/Cu(100) superstructure on Cu(100), PTCDA forms an incommensurate monolayer with a structure that corresponds well to that of PTCDA bulk lattice planes.
关键词： PTCDA,STM,template,thin organic films,LEED,Cu(100)
更新于2025-09-04 15:30:14
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Micro Structural and Optical Properties of Ferrous Selenide Thin Films and Its Characterization
摘要： Ferrous Selenide (FeSe) thin films were prepared onto glass substrate by Electron beam evaporation technique. X-Ray Diffractometer analyses showed that highly c-axis oriented and high-quality films were obtained on various annealing temperatures of 100°C, 200°C and 300°C respectively. From Scanning Electron Microscopy and its Elemental analysis of all the films showed low-temperature structural phase transition at different annealing temperatures of RT, 100°C, 200°C and 300°C respectively. The optical studies of FeSe thin film on glass was found most different from all the others, and its bandgap decreases from 2.85 eV to 2.75 eV for different annealing temperatures of the thin films. Optical analysis is demonstrated that Ferrous (Fe) and Selenide (Se) are homogeneously distributed in the film. Atomic Force Microscopy (AFM) and its 2D and 3D analyses were found that microstructure of FeSe thin films.
关键词： Morphology,Structural,Optical,FeSe thin films
更新于2025-09-04 15:30:14
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Influence of complexing agent on the growth of chemically deposited Ni3Pb2S2 thin films
摘要： Ni3Pb2S2 thin films were prepared by chemical bath deposition method. Here, the objective of this research is to investigate the influence of complexing agent on the properties of films.These films were characterized using atomic force microscopy, UV-Visible spectrophotometery and X-ray diffraction. It was found that the increase in the concentration of tartaric acid, film thickness increased, but, the band gap reduced. For the films prepared using 0.1M of tartaric acid, were found uniform and completely covered with the substrates.
关键词： chemical bath deposition,band gap,thin films,thickness
更新于2025-09-04 15:30:14
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Thin Film Processes - Artifacts on Surface Phenomena and Technological Facets || Layer-by-Layer Thin Films and Coatings Containing Metal Nanoparticles in Catalysis
摘要： The layer-by-layer (LbL) technique is one of the most promising ways of fabricating multilayer thin films and coatings with precisely controlled composition, thickness, and architecture on a nanometer scale. This chapter considers the multilayer thin films and coatings containing metal nanoparticles. The main attention was paid to LbL films containing metal nanoparticles assembled by convenient methods based on the different intermolecular interactions, such as hydrogen bonding, charge transfer interaction, molecular recognition, coordination interactions, as driving force for the multilayer buildup. Much attention has paid to the LbL films containing metal nanocomposites for multifunctional catalytic applications, in particular, photocatalysis, thermal catalysis, and electrocatalysis. The preparation protocol of LbL-assembled multilayer thin films containing metal nanoparticles (such as Au, Ag, Pd, Pt), metal oxides (Fe3O4), and sulfides (CdS) that are supported on the various surfaces of nanotubes of TiO2, Al2O3 membranes, graphene nanosheets, graphene oxide and further applications as catalysts with respect to photocatalytic, electrocatalytic performances is discussed. The systematization and analysis of literature data on synthesis, characterization, and application of multilayer thin films and coatings containing metal nanoparticles on the diverse supports may open new directions and perspectives in this unique and exciting subject.
关键词： semiconductors,metal nanoparticles,polyelectrolytes,layer-by-layer assembling,thin films and coatings,immobilization,catalysts
更新于2025-09-04 15:30:14
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Electrodeposition and characterization of SnS-electrochemically reduced graphene oxide heterojunction
摘要： This work shows the formation of a heterojunction between tin (II) sulfide (SnS) and electrochemically reduced graphene oxide (ERGO) carried out through two electrochemical steps. In the first step, graphene oxide (GO) was electrochemically reduced on a fluorine-doped tin oxide (FTO) electrode. In the second step, the ERGO/FTO substrate was used as an electrode for the electrodeposition of SnS. In this study, each material electrodeposited (ERGO, SnS and SnS/ERGO heterojunction) was analyzed and characterized using different techniques, which confirmed the SnS/ERGO heterojunction formation. By employing electrochemical impedance spectroscopy (EIS) and linear sweep photovoltammetry measurements, it was confirmed that SnS deposited in both, bare FTO and ERGO, is a p-type semiconductor. Furthermore, an improvement of the photocatalytic properties of the SnS/ERGO photocathode in comparison with the SnS film was observed. This effect is related to the ERGO interlayer between the SnS film and the FTO electrode, and the structural and morphology modification of the SnS film onto ERGO.
关键词： semiconductors,electrodeposition,water splitting,graphene oxide,thin films
更新于2025-09-04 15:30:14
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Structural and Photoluminescence Properties of nc-SiOx:H/a-SiOx:H Multilayer Films Deposited at Low Temperature by VHF-PECVD Technique
摘要： Hydrogenated nanocrystalline silicon oxide/hydrogenated amorphous silicon oxide (nc-SiOx:H/a-SiOx:H) multilayer films were fabricated using very-high-frequency plasma-enhanced chemical vapor deposition (VHF-PECVD) technique by alternate deposition of nc-SiOx:H and a-SiOx:H at a low substrate temperature of 220 °C. The effects of the amount of oxygen incorporation in the nc-SiOx:H sublayers on the structural and photoluminescence (PL) properties of nc-SiOx:H/a-SiOx:H multilayer films were investigated by transmission electron microscopy, Raman scattering, UV–VIS-NIR absorption spectra, steady and time-resolved PL spectra. As the amount of oxygen incorporation increases, the crystalline volume fraction of multilayer films decreases, while the intermediate-range order of multilayer films firstly increases and then decreases. Strong room temperature PL has been observed in the multilayer films and the correlation between structural and PL properties is discussed. This low-temperature procedure for fabricating nc-SiOx:H/a-SiOx:H multilayer films can provide powerful impetus for the further development of optoelectronic devices based on Si-NCs.
关键词： Hydrogenated nanocrystalline silicon oxide,VHF-PECVD,Photoluminescence,Multilayer films
更新于2025-09-04 15:30:14
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Preparation of highly visible transparent ZnO/cellophane UV-shielding film by RF magnetron sputtering
摘要： A novel UV-shielding ?lm created by sputtering ZnO ?lm onto a renewable and biodegradable cellophane ?lm is proposed. The dependence of the optical properties of the ZnO/cellophane hybrid ?lm on the sputtering power, pressure, and ?lm thickness was studied systematically. A high crystalline quality ZnO ?lm with preferred [002] orientation was prepared on a cellophane substrate for the ?rst time. Unlike conventional UV-shielding ?lms consisting of nanostructures and synthetic polymers, ZnO/cellophane hybrid ?lm can possess high visible light transparency and excellent UV-shielding capacity at the same time. The improved performance can be attributed to the high crystalline quality and the antire?ection e?ect of the ZnO ?lm. A typical hybrid ?lm exhibits a UV-shielding ratio of 96.5% while exhibiting a transmittance of visible light of over 80%. ZnO/cellophane hybrid ?lms can be applied in a vast range of UV-shielding applications, such as sunburn protection and short-wave radiation protection in the laboratory.
关键词： ZnO(D),Films(A),Optical properties(C),UV-shielding
更新于2025-09-04 15:30:14