Structural,Morphological and Optical Properties of Nanostructure Nickel Oxide Thin Films on Quartz Substrates Grown by Plasma Oxidation

In this work nanocrystalline nickel oxide (NiO) thin films were successfully prepared by oxygen plasma treatment of nickel films deposited on quartz substrates by direct current magnetron sputtering technique. The prepared films were characterized by XRD, XPS, FTIR, RBS, AFM, FESEM and spectrophotometry for investigation of oxygen plasma treatment power effect on structural, morphological and optical properties of prepared films. It was found that NiO films crystallize in cubic phase structure and an oxygen plasma treatment powers effectively influenced the preferred orientations. The FESEM and AFM images showed a granular structure with spherical shapes of grains for all prepared films. The size of grains was in range 23–30 nm. The transmittance and optical band gap were found to be sensitive to plasma power.     

Influence of N2/Ar gas mixture ratio and annealing on optical properties of SiCBN thin films prepared by rf sputtering

Optical properties of amorphous thin films of silicon carbon boron nitride (Si–C–B–N) obtained by reactive sputtering has been studied. Compositional variations were obtained by changing the nitrogen and argon gas mixture ratio in the sputtering ambient. The effect of gas ratios and annealing on the optical properties was investigated. It was found that the transmittance of the films increases with nitrogen incorporation. Annealing at higher temperatures leads to considerable increase in transmittance. Optical energy gap (Tauc gap) calculated from absorption data is influenced by annealing temperatures and reactive process gas mixture. Changes in optical properties were correlated to the chemical modifications in the films due to annealing, through X-ray photoelectron spectroscopy. Studies reveal that the carbon and nitrogen concentrations in the films are highly sensitive to temperature. Annealing at higher temperatures leads to broken C–N bonds which results in the loss of C and N in the films. This is believed to be the primary cause for variations in optical properties of the films.     

Physical properties of spray deposited Ni-doped zinc oxide thin films

Transparent thin films of nickel doped zinc oxide were deposited on to corning glass substrates via chemical spray pyrolysis using zinc acetate and nickel nitrate as precursors. Structural, morphological, optical, electrical, dielectrical and impedance properties of the films as a function of nickel doping concentration as well as inter-particle interactions by complex impedance spectroscopy were investigated. The deposited films are polycrystalline with a hexagonal (wurtzite) crystal structure along (002) preferential orientation. The films are highly transparent in the visible region with a transmittance higher than 86%, and have an optical band gap ranging from 3.23 to 3.19 eV depending on the nickel doping concentration. The high electrical conductivity of doped films is explained on the basis of the presence of oxygen vacancies. Decrease of electrical conductivity due to nickel doping is explained on the basis of compensation of oxygen vacancies. The dielectric constant and loss tangent as a function of frequency are reported. Interparticle interactions in the deposited films are studied by complex impendence spectroscopy.     

酰胺化纳米晶纤维素提高乙烯-醋酸乙烯酯共聚物薄膜阻透性的研究

合成了三种酰胺化纳米晶纤维素,并采用溶液共混成膜法制备了酰胺化纳米晶纤维素（CNC）/乙烯醋酸乙烯醋共聚物(EVA)复合膜材料。通过紫外-可见分光光度计、电子万能试验机和透湿仪研究了酰胺化CNC/ EVA复合膜的光学性能、力学性能以及水蒸气阻隔性,并通过原子力显微镜研究热压处理的EVA复合膜的表面形貌。结果表明,添加三种不同碳链的酰胺化CNC都使 EVA膜的透光率有所降低,当添加量为5 %时,EVA膜透光率仍高达90%。一定程度的热压能够让酰胺化纳米晶纤维素在EVA基体中分散更均匀,使EVA复合膜的透光率提高了2%～3%;随着纳米晶纤维素含量的逐渐增加,三种酰胺化CNC/EVA膜的拉伸强度均逐渐增强,透湿率（WVTR值）均减小;酰胺化CNC含量相同时, 十六胺改性的纳米晶纤维素(CNC-N16)/EVA复合膜的力学性能和水蒸气阻隔效果优于相应的十二胺和正辛胺。     

Physicochemical and antibacterial properties of chitosan‐polyvinylpyrrolidone films containing self‐organized graphene oxide nanolayers

Chitosan films have a great potential to be used for wound dressing and food‐packaging applications if their physicochemical properties including water vapor permeability, optical transparency, and hydrophilicity are tailored to practical demands. To address these points, in this study, chitosan (CS) was combined with polyvinylpyrrolidone (PVP) and graphene oxide (GO) nanosheets (with a thickness of ～1 nm and lateral dimensions of few micrometers). Flexible and transparent films with a high antibacterial capacity were prepared by solvent casting methods. By controlling the evaporation rate of the utilized solvent (1 vol % acidic acid in deionized water), self‐organization of GO in the polymer matrix was observed. The addition of PVP to the CS/GO films significantly increased their water vapor permeability and optical transmittance. A blue shift in the optical absorption edge was also noticed. Thermal analysis coupled with Fourier transform infrared spectroscopy suggested that the superior thermal stability of the nanocomposite films was due to the formation of hydrogen bonds between the functional groups of chitosan with those of the graphene oxide. An improved bactericidal capacity of the nanocomposite films against gram‐positive Staphylococcus aureus and gram‐negative Escherichia coli bacteria was also observed. Highly flexible, transparent (opacity of 6.95), and antimicrobial CS/25 vol % PVP/1 wt % GO films were prepared. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43194.     

Enhanced conductance properties of UV laser/RTA annealed Al-doped ZnO thin films

Thin films comprising 0.5 mol% aluminum-doped zinc oxide (AZO) were prepared on glass substrates by a spin-coating method for transparent conducting oxide (TCO) applications. UV laser was selected for the annealing of AZO thin films, due to the well matched energy bandgap between UV laser and AZO films. After the rapid thermal annealing (RTA) process, post UV laser annealing was carried out by varying the scan speed of the laser beam, and the effects of laser annealing on the structural, morphological, electrical, and optical properties were analyzed. The results indicated that UV laser annealing based on various scan speeds affects the microstructure, sheet resistance, and optical transmittance of the AZO thin films, compared with those of the only RTA processed thin films. X-ray diffraction (XRD) analysis showed that all films that preferentially grew normally on the substrate had a (002) peak. The optical transmittance spectra of the laser/RTA annealed AZO thin films exhibited greater than 83% transmittance in the visible region. Also, the sheet resistance (1.61 kΩ/sq) indicated that optimized UV laser annealing after the RTA process improves film conductance.     

Developing high-transmittance heterojunction diodes based on NiO/TZO bilayer thin films

In this study, radio frequency magnetron sputtering was used to deposit nickel oxide thin films (NiO, deposition power of 100 W) and titanium-doped zinc oxide thin films (TZO, varying deposition powers) on glass substrates to form p(NiO)-n(TZO) heterojunction diodes with high transmittance. The structural, optical, and electrical properties of the TZO and NiO thin films and NiO/TZO heterojunction devices were investigated with scanning electron microscopy, X-ray diffraction (XRD) patterns, UV-visible spectroscopy, Hall effect analysis, and current-voltage (I-V) analysis. XRD analysis showed that only the (111) diffraction peak of NiO and the (002) and (004) diffraction peaks of TZO were observable in the NiO/TZO heterojunction devices, indicating that the TZO thin films showed a good c-axis orientation perpendicular to the glass substrates. When the sputtering deposition power for the TZO thin films was 100, 125, and 150 W, the I-V characteristics confirmed that a p-n junction characteristic was successfully formed in the NiO/TZO heterojunction devices. We show that the NiO/TZO heterojunction diode was dominated by the space-charge limited current theory.     

非晶硅太阳能电池背反ZnO:Al薄膜制备

以ZnO:Al(2%Al2O3,质量分数)为靶材,用射频磁控溅射在玻璃衬底上制备ZnO:Al薄膜,分析了各沉积参数对薄膜光电性能的影响。结果表明:溅射功率对ZnO:Al的透过率影响最大,其次是反应腔室压力,而衬底温度对透过率几乎没有影响。ZnO:Al的电阻率主要取决于衬底温度和溅射功率。综合考虑透过率和电阻率,确定了背反ZnO:Al的最佳沉积参数(衬底温度为200℃,溅射功率为200W,反应腔室压力为0.6Pa),得到了透过率大于85%,电阻率最小为7.6×10-4Ωcm的ZnO:Al薄膜。制备了ZnO:Al/Ag/ss(stainless steel)背反电极,并将其用于非晶硅太阳能电池。与无背反的不锈钢衬底上的电池相比,非晶硅太阳能电池短路电流密度增加了16%。     

Stretchable conductive films based on carbon nanomaterials prepared by spray coating

Stretchable conductive films consisting of a layer of carbon nanomaterials, that is, carbon nanotubes (CNTs), mechanically exfoliated graphene (GE), or chemically reduced graphene oxide (rGO), deposited on polydimethylsiloxane (PDMS) films were prepared by spray coating. The correlations among the concentration of the carbon nanomaterials, the electrical resistance and the optical transmittance of the spray‐coated films were investigated. The results show that the conductivity of the CNT coatings was better than that of the GE‐based coatings. When the CNT concentration of the dispersion for spraying increased from 0.01 to 0.075 mg/mL, the surface electrical resistance decreased from 7.8 × 10³ to 6.7 × 10² Ω, whereas for the GE or rGO coatings, the electrical resistance was several orders higher than that of the CNT coatings. The CNT spray‐coated films exhibited an optical transmittance of about 60% at a wavelength of 550 nm; this was higher than that of the GE or rGO spray‐coated films. The electric heating behaviors of the stretchable conductive films as functions of the applied voltage and the concentration of carbon nanomaterials and the electrical conductivity under tensile and bending strains were also investigated. The surface temperature of the CNT‐coated films rose rapidly up to 200°C within about 40 s when the applied voltage was 110 V. The stretchable conductive films have potential as electric heating elements because of their excellent conductive properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43243.     

Interactions of supported nickel and nickel oxide catalysts with methane and steam at high temperatures

The catalytic performance of cermets made of 10% nickel or nickel oxide supported on YSZ (yttria-stabilized zirconia) for chemical looping combustion (CLC) and steam reforming (SR) of methane at 700 °C is investigated. Steam reforming of methane over the reduced catalyst resulted in a syngas containing more than 70% hydrogen and about 15% carbon monoxide. Chemical looping combustion of methane with insufficient lattice oxygen could potentially lead to 40–65% hydrogen rich gas products. Prolonged induction period (e.g. 30–80 min) in reduction of nickel oxide by methane has been observed in the presence of steam. The span of induction period increases by increasing steam partial pressure. It is hypothesized that the delayed reduction of nickel oxide is related to the retarding effect of steam on autocatalytic reactions of methane and hydrogen with lattice oxygen of nickel oxide and the subsequent reforming reactions.     

Influence of a Ni interlayer on the optical and electrical properties of trilayer GZO/Ni/GZO films

Trilayer GZO/Ni/GZO films were deposited onto polycarbonate (PC) substrates with RF and DC magnetron sputtering, and then the influence of a Ni interlayer on the optical and electrical properties of the films was investigated. A 2-nm-thick Ni interlayer decreased the resistivity to 6.4×10⁻⁴ Ω cm and influenced the optical transmittance.Although optical transmittance deteriorated with Ni insertion, the films showed a relatively high optical transmittance of 74.5% in the visible wavelength region. The figure of merit (FOM) of a GZO single layer film was 1.2×10⁻⁴ Ω⁻¹, while that of the GZO/Ni/GZO films reached a maximum of 8.2×10⁻⁴ Ω⁻¹.Since a higher FOM results in higher quality transparent-conductive oxide (TCO) films, it is concluded that GZO films with a 2 nm Ni interlayer have better optoelectrical performance than single-layer GZO films.     

Study of a sandwich structure of transparent conducting oxide films prepared by electron beam evaporation at room temperature

ABSTRACT: Transparent conducting ZnO/Ag/ZnO multilayer electrodes having electrical resistance much lower than that of widely used transparent electrodes were prepared by ion-beam-assisted deposition (IAD) under oxygen atmosphere. The optical parameters were optimized by admittance loci analysis to show that the transparent conducting oxide (TCO) film can achieve an average transmittance of 93%. The optimum thickness for high optical transmittance and good electrical conductivity was found to be 11 nm for Ag thin films and 40 nm for ZnO films, based on the admittance diagram. By designing the optical thickness of each ZnO layer and controlling process parameters such as IAD power when fabricating dielectric-metal-dielectric films at room temperature, we can obtain an average transmittance of 90% in the visible region and a bulk resistivity of 5 x 10^-5 ohm-cm. These values suggest that the transparent ZnO/Ag/ZnO electrodes are suitable for use in dye-sensitized solar cells.     

Behavior of Metallic Components During 4,000 h Operation of an SOFC Stack with Carbon Containing Fuel Gas

In the present study the behavior of the ferritic interconnect steel Crofer 22 APU and the nickel contacting material during exposure in anode gas of a solid oxide fuel cell (SOFC) stack was investigated. The stack had been operating for 4,000 h and was ten times subjected to thermal cycling within this time period. A temporary high carbon activity in the fuel gas combined with temperature changes resulted in local disintegration of the nickel mesh. Additionally, nickel diffusion from the nickel mesh into the steel resulted in the formation of an austenitic zone. Diffusion of steel constituents into the nickel mesh lead to the formation of Cr,Mn‐oxides in the latter. Presence of the nickel/steel contact allows transport of carbon from the gas into the steel, resulting in local internal carburization of the steel. In areas which were not in direct contact with the nickel mesh, the Crofer 22 APU interconnect formed a protective surface oxide scale and no indications for carbon uptake were found. Mechanisms for the experimentally observed effects, including the local disintegration of the nickel mesh, are presented.     

Effects of NIR annealing on the characteristics of al-doped ZnO thin films prepared by RF sputtering

Aluminum-doped zinc oxide (AZO) thin films have been deposited on glass substrates by employing radio frequency (RF) sputtering method for transparent conducting oxide applications. For the RF sputtering process, a ZnO:Al₂O₃ (2 wt.%) target was employed. In this paper, the effects of near infrared ray (NIR) annealing technique on the structural, optical, and electrical properties of the AZO thin films have been researched. Experimental results showed that NIR annealing affected the microstructure, electrical resistance, and optical transmittance of the AZO thin films. X-ray diffraction analysis revealed that all films have a hexagonal wurtzite crystal structure with the preferentially c-axis oriented normal to the substrate surface. Optical transmittance spectra of the AZO thin films exhibited transmittance higher than about 80% within the visible wavelength region, and the optical direct bandgap (E_g) of the AZO films was increased with increasing the NIR energy efficiency.     

Recycling wood pulping chemicals by molten salt electrolysis: cyclic voltammetry of mixtures containing Na2CO3 and Na2SO4

We are investigating a novel electrochemical pathway for efficient recycling of inorganic chemicals from the kraft pulping process. To analyse this process, cyclic voltammetry was conducted on molten salts containing sodium carbonate, or sodium carbonate and sodium sulfate on gold and nickel/nickel oxide electrodes. Pure sodium carbonate at 860 °C was determined to exhibit oxidation to carbon dioxide and oxygen. Electrochemical reduction proceeded to both sodium metal and to sodium oxide and either carbon or carbon monoxide. A mixture with a 2.36:1 molar ratio of sodium carbonate to sodium sulfate at 860 °C was investigated where the anode again displayed carbonate oxidation. The cathode reactions are the reduction of sulfate ions to form sulfide and oxide ions and carbonate reduction to oxide ions and carbon monoxide. Separated cell operation to avoid oxide ion oxidation appears necessary according to the cyclic voltammetry. Nickel oxide was found to be a stable anode material in a sodium carbonate molten salt. This paper, based on cyclic voltammetry results of oxide ion production, is the first step towards a technical electrolysis process for recausticizing of molten smelt for the kraft pulping process.     

Greatly improved NIR shielding performance of CuS nanocrystals by gallium doping for energy efficient window

In this work, gallium doped copper sulfide (Ga-doped CuS) nanocrystals were prepared using a solvothermal method. The effects of Ga doping on the crystal structures, chemical composition, morphology, optical properties and thermal performance of copper sulfide (CuS) were investigated. The Ga-doped CuS nanocrystals had a hexagonal structure comparable to that of pure CuS. The Cu⁺/Cu²⁺ ratio first decreased and then increased with increasing Ga³⁺ doping. Both CuS and Ga-doped CuS exhibited nanoplate and nanorod morphologies. The visible transmittance of the Ga-doped CuS films was in the range of 61–77.1%. Importantly, the near-infrared (NIR) shielding performance of the films can be tuned by adjusting the concentration of the Ga dopant. The NIR shielding value of the optimal Ga-doped CuS film was 72.4%, which was approximately 1.5 times as high as that of the pure CuS film. This can be ascribed to the enhanced plasmonic NIR absorption that resulted from an increase in the hole concentration after doping with Ga³⁺ ions. In the thermal performance test, the Ga-doped CuS film lowered the interior temperature of the heat box by 9.1 °C. Therefore, the integration of good visible transmittance and high NIR shielding performance make the Ga-doped CuS nanocrystals a promising candidate for energy-efficient window coatings.     

Electrochromic properties of porous NiO thin film as a counter electrode for NiO/WO3 complementary electrochromic window

Highly porous nickel oxide (NiO) thin films were prepared on ITO glass by chemical bath deposition (CBD) method. SEM results show that the as-deposited NiO film is constructed by many interconnected nanoflakes with a thickness of about 20 nm. The electrochromic properties of the NiO film were investigated in a nonaqueous LiClO₄–PC electrolyte by means of optical transmittance, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements. The NiO film exhibits a noticeable electrochromic performance with a variation of transmittance up to 38.6% at 550 nm. The CV and EIS measurements reveal that the NiO film has high electrochemical reaction activity and reversibility due to its highly porous structure. The electrochromic (EC) window based on complementary WO₃/NiO structure shows an optical modulation of 83.7% at 550 nm, much higher than that of single WO₃ film (65.5% at 550 nm). The response time of the EC widow is found to be about 1.76 s for coloration and 1.54 s for bleaching, respectively. These advantages such as large optical modulation, fast switch speed and excellent cycle durability make it attractive for a practical application.     

Novel preparation of ITO nanocrystalline films with plasmon electrochromic properties by the sol-gel method using benzoylacetone as a chemical modifier

In this paper, benzoylacetone (BzAcH) was introduced as a chelating agent to the sol-gel technique to fabricate indium tin oxide (ITO) nanocrystalline films. BzAcH was found to decrease the grain size of the ITO film, and the growth of ITO nanocrystals was controlled by varying the BzAcH content. ITO nanocrystalline films prepared by this method showed significant localized surface plasmon resonance (LSPR) absorption features that could be manipulated electrically by electrochemical doping. Plasmonic electrochromism realized in ITO films indicated a strongly reversible and persistent variation of the film transmittance in the near-infrared region (NIR). Furthermore, the plasmon electrochromic mechanism of ITO nanocrystals is discussed in this paper.     

In situ photoelectrochemistry and Raman spectroscopic characterization on the surface oxide film of nickel electrode in 30 wt.% KOH solution

The oxide films of nickel electrode formed in 30 wt.% KOH solution under potentiodynamic conditions were characterized by means of electrochemical, in situ PhotoElectrochemistry Measurement (PEM) and Confocal Microprobe Raman spectroscopic techniques. The results showed that a composite oxide film was produced on nickel electrode, in which aroused cathodic or anodic photocurrent depending upon polarization potentials. The cathodic photocurrent at −0.8 V was raised from the amorphous film containing nickel hydroxide and nickel monoxide, and mainly attributed to the formation of NiO through the separation of the cavity and electron when laser light irradiates nickel electrode. With the potential increasing to more positive values, Ni₃O₄ and high-valence nickel oxides with the structure of NiO₂ were formed successively. The composite film formed in positive potential aroused anodic photocurrent from 0.33 V. The anodic photocurrent was attributed the formation of oxygen through the cavity reaction with hydroxyl on solution interface. In addition, it is demonstrated that the reduction resultants of high-valence nickel oxides were amorphous, and the oxide film could not be reduced completely. A stable oxide film could be gradually formed on the surface of nickel electrode with the cycling and aging in 30 wt.% KOH solution.     

Reaction of nitric oxide and nitric oxide + carbon monoxide with amorphous Fe-Co-B alloy powders

The activity of amorphous Fe---Co---B alloy powder was investigated for the decomposition and the reduction of nitrogen monoxide. The transient response technique and a fixed bed reactor were applied to study the interactions of the Fe---Co---B alloy with two gas mixtures: NO + Ar at 353 and 573 K and NO + CO + Ar at 333–573 K. Moessbauer spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to study the state of the initial sample and the samples utilized in both gas mixtures. It is shown that the amorphous Fe---Co---B alloy powder has an activity for the direct decomposition of nitric oxide to nitrous oxide and nitrogen at a high gas space velocity (26 000 h⁻¹). Oxygen from the decomposed nitric oxide poisons the surface for the formation of nitrogen. In the presence of carbon monoxide (a NO + CO + Ar gas mixture) nitric oxide is reduced to nitrous oxide at 333–353 K and fully reduced to nitrogen at 373–573 K. The quantities of the carbon dioxide formed are not equal to the values expected from the stoichiometry of the NO + CO reaction. Probably, the interaction of carbon monoxide with the adsorbed oxygen (left on the surface by the decomposed nitric oxide) enhances the rate of nitric oxide decomposition to nitrous oxide and nitrogen. The rate limiting steps for both reactions of nitric oxide decomposition, as indicated by the transient response data, change with increasing temperature. The data from the Moessbauer spectroscopy and the X-ray photoelectron spectroscopy (XPS) studies have shown that the amorphous Fe---Co---B alloy powder undergoes phase changes under the conditions of both, the NO + Ar and the NO + CO + Ar gas mixtures. Boron migrates to the surface of globules and serves the accumulation of oxygen by the formation of B₂O₃ (or B(OH)₃).