Preparation and electrical conductivity of thin films of Rb4Cu16I7Cl13

A thin film of the copper ion conductor Rb₄Cu₁₆I₇Cl₁₃ was prepared on a glass plate by vacuum evaporation. An appropriate thin film was obtained by controlling the amount of the electrolyte mounted in a boat, the evaporation time etc. and by heating the deposited film at a temperature between 130 and 210° C. The electronic and ionic conductivities of the film measured by d.c. and a.c. techniques were nearly equal to those of a dense tablet of the solid electrolyte.     

钒酸银光催化降解氯胺磷的研究

以NH_4VO_3和AgNO_3为原料,采用溶剂热法制备了新型可见光催化剂Ag_3VO_4。利用XRD、SEM和UV-Vis等测试手段对样品的结构、形貌及光吸收性能进行了表征,并以有机磷农药氯胺磷为目标降解物,考查了催化剂的可见光催化性能。结果表明:所得Ag_3VO_4晶体结构属于单斜晶相,在反应体系pH值较高时所得样品的形貌为棒状,具有较好的可见光吸收性能,对氯胺磷有较好的降解效果。     

Synthesis and characterization of CdS nanocrystals embedded on solid electrolyte films

In this article nano‐sized CdS crystal embedded in a PEO matrix was successfully prepared by a complex transformation method that is universal for preparing nanosized compounds containing transition metals. The size of embedded CdS particles was in the nanoscale from 2 to 10 nm determined by X‐ray diffusion. The nanosized CdS displayed the expected blue shift of the onset absorbance in the UV spectrum. The amount of blue shift depends upon the dipping time of the PEO–cadmium complex film in a sodium sulfide solution as well as its concentration. The most effective means for adjusting the size of CdS nanocrystals is to change the ratio of the oxygen along with the PEO chain to the cadmium ion in the complex film. The alkali salt in the film would contribute to the conductivity of the composite film. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1263–1268, 2002; DOI 10.1002/app.10459     

Electrochemical investigation on the contact in solid state cells with an RbAg4 I5 electrolyte

The contact between a silver electrode and the solid electrolyte RbAg₄I₅ is investigated by means of impedance and cyclic voltammetry. From the observed dependence of the electrolyte resistance and the maximum current density achievable in cyclic voltammetry on the pressure applied, an attempt is made to calculate the real contact areas.     

Transport properties of sulfide-conductive solid electrolyte in the system CaYb2S4-Yb2S3

CaYb₂S₄-based phases with a superstoichiometric content of Yb₂S₃ to be used for depositing thin-layer sulfur-containing coatings were obtained for the first time. The attestation of the samples was performed using X-ray diffraction and electron microscopy. The conductometry was used to measure the complex electroconductivities of the samples, whereas the bulk and intergrain components were determined by means of impedance spectroscopy. Based on conductometry and potentiometric chronoamperometry data, the selfdiffusion and effective diffusion coefficients were determined. In order to predict the application area, the working range of sulfur partial pressures was determined using the emf method.     

Electrophoretically deposited thin film electrolyte for solid oxide fuel cell

Abstract

Thin films of 8 mol% yttria stabilised zirconia (YSZ) electrolyte have been deposited on non-conducting porous NiO–YSZ anode substrates using electrophoretic deposition (EPD) technique. Deposition of such oxide particulates on non-conducting substrates is made possible by placing a conducting steel plate on the reverse side of the presintered porous substrates. Thickness of the substrates, onto which the deposition has been carried out, varied in the range 0·5–2·0 mm. Dense and uniform YSZ thin films (thickness: 5–20 μm) are obtained after being cofired at 1400°C for 6 h. The thickness of the deposited films is seemed to be increased with increasing porous substrate thickness. Solid oxide fuel cell (SOFC) performance is measured at 800°C using coupon cells with various anode thicknesses. While a peak power density of 1·41 W cm^?2 for the cells with minimum anode thickness of 0·5 mm is achieved, the cell performance decreases with anode thickness.     

Thermomechanical studies on newly developed copolyester thin films. Part I: Thermal expansion coefficients

In this paper, the in-plane linear coefficients of thermal expansion (CTE) (αx and αy) of a newly developed family of all aromatic and aromatic/aliphatic copolyester thermoset films prepared from spin coating were measured. The volumetric CTEs (β) were determined by a Pressure-Volume-Temperature (PVT) technique (1). Based on the difference between the volumetric CTEs and the sum of the in-plane linear CTEs, the out-of-plane linear CTEs (αz) were calculated. The effects of film processing, including film coating and curing, on the CTEs are discussed. It was found that the linear CTEs varied significantly with the processing conditions, the volumetric CTEs were essentially constant, and the out-of-plane linear CTEs (αz) of the spin coated films were higher than the in-plane linear CTEs (αx, y).     

Synthesis and characterization of VO2-based thermochromic thin films for energy-efficient windows

Thermochromic VO2 thin films have successfully been grown on SiO2-coated float glass by reactive DC and pulsed-DC magnetron sputtering. The influence of substitutional doping of V by higher valence cations, such as W, Mo, and Nb, and respective contents on the crystal structure of VO2 is evaluated. Moreover, the effectiveness of each dopant element on the reduction of the intrinsic transition temperature and infrared modulation efficiency of VO2 is discussed. In summary, all the dopant elements--regardless of the concentration, within the studied range-- formed a solid solution with VO2, which was the only compound observed by X-ray diffractometry. Nb showed a clear detrimental effect on the crystal structure of VO2. The undoped films presented a marked thermochromic behavior, specially the one prepared by pulsed-DC sputtering. The dopants effectively decreased the transition of VO2 to the proximity of room temperature. However, the IR modulation efficiency is markedly affected as a consequence of the increased metallic character of the semiconducting phase. Tungsten proved to be the most effective element on the reduction of the semiconducting-metal transition temperature, while Mo and Nb showed similar results with the latter being detrimental to the thermochromism.     

Surface roughness of thin silver films pulse-plated using silver cyanide-thiocyanate electrolyte

We investigated the effect of the pulse current density, current-on time and current-off time on the surface roughness of a silver thin film that was pulse-plated using a silver cyanide-thiocyanate electrolyte. The interface width, which is defined by the root mean square of the fluctuations in the height of the surface, is found to decrease rapidly with the current-off time and to increase with current-on time. However, it should be noted that when the value of current-off time is sufficiently large, the interface width decreases with pulse current density. These experimental results indicate that by appropriate selection of the current-on time and current-off time, we can fabricate silver electrodeposits with minimal surface roughness. We have discussed the influence of these three parameters on the interface width from the viewpoint of the cathode potential and adsorption.     

Transport models for swelling and dissolution of thin polymer films

Fundamental models have been developed to describe swelling and dissolution of glassy polymer thin films. The models account for solvent penetration by either Fickian or Case II diffusion mechanims. The convective flux due to local swelling as the solvent penetrates is included. Chain disentanglement at the polymer-developer solution interface is scaled with the local solvent concentration and polymer molecular weight using reptation theory. The effective surface concentration during dissolution is estimated by applying thermodynamics of swollen networks to the entangled polymer. Swelling and dissolution of thin polymer films have direct application to microlithography. Various molecular and processing parameters affect the outcome of resist development. The utility of the models for selecting appropriate developer solvents, minimizing resist swelling, and providing a better understanding of the swelling and dissolution of resists is demonstrated.     

Water diffusion studies in polyimide thin films

The water diffusion behaviors and activation energies of PDA- and ODA-based polyimide thin films were quite dependent on both the chemical structure and the morphological structure in the films. The water diffusion coefficients of polyimide thin films increased with increasing temperature. The activation energies varied in the range of 5.81 to 9.27 kcal/mol and were relatively higher for the PDA-based polyimide thin films than for the corresponding ODA-based polyimide thin films. For the PDA- and ODA-based polyimide films, the differences in the morphological structures and the chemical affinity to water molecules might be reflected directly on the water diffusion behaviors. The PDA-based polyimide films exhibited a relatively more ordered morphological structure (high crystallinity and good in-plane orientation) than that of the corresponding ODA-based polyimide thin films, which may serve as impenetrable obstacles for the water diffusion in the out-of-plane direction. Consequently, it may lead to a relatively slower water diffusion and high activation energy in the PDA-based polyimide thin films. Additionally, the PDA-based polyimide films with relatively lower chemical affinity showed relatively low diffusion coefficients and high activation energies. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 731–737, 2001     

Selective photocatalytic degradation of azodyes in NiO/Ag3VO4 suspension

BACKGROUND: This work deals with the development of an active heterogeneous catalyst for selective organic synthesis under both visible light and UV irradiation to utilize efficiently solar light. Very few studies have been reported on the selective photooxidation performance of multimetal oxide materials under visible light irradiation. The photocatalytic degradation of azodyes was investigated systematically in aqueous NiO/Ag₃VO₄ dispersion under visible light irradiation. RESULTS: The catalyst NiO/Ag₃VO₄ showed high activity and selectivity for the photodegradation of the nonbiodegradable azodyes acid red B, reactive brilliant red X‐3B, and acid orange 7. From total organic carbon (TOC), Fourier transform infrared spectroscopy (FTIR), and gas chromatography/mass spectroscopy analyses, the tested azodyes were selectively oxidized into aromatic and aliphatic acids without any decrease of TOC. The high photooxidation selectivity also applied to UV light irradiation. Electron spin resonance and radical scavenger studies suggest that the anionic superoxide radical O₂^?? was the predominant active species in the photocatalytic reaction. CONCLUSION: The selectivity of NiO/Ag₃VO₄ for the oxidation of azodyes was not affected by the energy of light (UV and visible light). This approach allows effective controlled oxidation but avoids undesirable mineralization into CO₂ and H₂O. Copyright © 2010 Society of Chemical Industry     

Ionic conduction in polymer films I. Influence of electrolyte on resistance

Ionic conduction in continuous polymer films is of two types. Inverse conduction occurs when the resistance of the film runs counter to, and direct conduction when the resistance follows, that of the external solution. The two types are interconvertible; the controlling factor is the water content of the film, which is governed by the nature of the polymer, the mode of preparation of the film, and the conditions of exposure.     

Magnetic studies on one-step chemically synthesized nickel ferrite thin films

Nickel ferrite thin films were synthesized at room temperature using one-step electrodeposition solution processing. Reaction kinetics was also proposed. An effect of air baking on the structural, surface morphological and magnetic properties was investigated. As-deposited nickel ferrite thin films were cubic in crystal structure. Calculated grain size after annealing was increased from 30 to 48 nm in addition to formation of rough surface morphology. Due to decrease in defect levels after air baking the annealed nickel ferrite thin film showed saturation magnetization of 268 emu/cc, higher than non-annealed (230 emu/cc), when used in magnetic studies.     

Selective growth and texturing of VO2(B) thin films for high-temperature microbolometers

Vanadium oxides exhibit a broad spectrum of physical properties due to their ability to form various compounds and polymorphs. To utilise a particular property, it is essential to selectively synthesise a desired phase. Herein, we demonstrate a method to selectively and reproducibly grow (00l)-textured VO₂(B) thin films using an amorphous SrTiO₃ buffer layer by sputtering at <350 °C, which enables their direct integration with read-out-integrated-circuits (ROICs), glass, and polymer substrates. The VO₂(B) films exhibit high temperature-coefficient-of-resistances (TCRs) (>−3.5%/K at 25 °C and >−1.5%/K at 95 °C) and low electrical resistivities (∼5 × 10⁻¹ Ω cm at 25 °C and <1 × 10⁻¹ Ω cm at 95 °C), which are favourable for realising highly-sensitive, low-noise, and high-temperature microbolometers. A robust thermal stability of these VO₂(B) thin films at ambient pressure will provide new opportunities to incorporate thermal sensing functions to various electronics.     

Synthesis and studies of exceptionally crystalline polyaniline thin films

Highly crystalline camphor sulfonic acid (CSA)‐doped polyaniline (PANI) thin films cast from m‐cresol and N‐methylpyrrolidone (NMP) were investigated. PANI powder prepared by chemical oxidative polymerization subjected to doping–de‐doping–re‐doping procedures was cast into thin films using NMP and m‐cresol as solvents. X‐ray diffraction (XRD) reveals the presence of exceptionally highly crystalline or rather ordered regions in the PANI film samples prepared from m‐cresol. Atomic force microscopy (AFM) images also support the presence of crystalline regions on the surface of these films. The DC electrical conductivity of m‐cresol‐cast PANI is found to be quite high, and much higher than that of NMP‐cast PANI. The free‐carrier absorption tail extending to the near‐infrared region observed in the optical absorption spectrum of the m‐cresol‐cast PANI films suggests a metallic nature and regular structural arrangement in these films. Both inter‐chain and intra‐chain ordering brought about as a result of CSA doping, secondary doping effect of m‐cresol and ultrasonication are suggested to be the prime factors contributing towards the observed excellent crystallinity of these PANI films as evident from the XRD and AFM studies. The marked thermal stability of the m‐cresol‐cast PANI films is also established based on the variation of DC electrical conductivity with temperature and on thermogravimetric analysis. Copyright © 2012 Society of Chemical Industry     

Microwave synthesis of ETS-4 and ETS-4 thin films

Engelhard titanosilicate (ETS-4) was successfully synthesized by microwave heating at 235 °C within 50 min. ETS-4 was synthesized using titanium(IV) butoxide as the titanium source. Microwave irradiation shortened the synthesis time considerably as compared to conventional heating which resulted in the rapid synthesis of ETS-4 in less than 1 h compared to 36–48 h for the traditional synthesis. Pulsed laser deposition and microwave treatment was also studied for the preparation of ETS-4 films on alumina.