Influence of the Layer Morphology on the Electrical Properties of Sol Gel Transparent Conducting Oxide Coatings

Tranparent conducting coatings have been prepared by sol gel methods either by a conventional sol-gel process (Antimony doped Tin Oxide—ATO, Aluminium doped Zinc Oxide—AZO) or a new wet chemical process using fully dispersed crystalline nanoparticles (ATO, Indium Tin Oxide—ITO). The dip coating technique has been used as deposition technique with single coating thickness varying from a few nanometer to ca. 400 nm. The layers have been fired in a furnace. Structural properties have been determined by x-ray diffraction and TEM analysis and the electrical properties by the van der Pauw/Hall measurement. Three different coating procedures have been used to investigate the effect on the structure, morphology and the electrical properties of the coatings. It is shown that the individual layer thickness in multilayer coatings influences dramatically the mentioned properties. Very thin individual layers favour a heterogeneous nucleation with dense columnar growth of the crystallites leading to low electrical resistivity ( 10^–3 cm), while thick individual layers result in a porous morphology made of small crystallites leading to resistivities in the 10^–2 cm range.     

Proton Magnetic Resonance and Molecular Simulation in Configurational and Conformational Analysis of Cyclohexanone Derivatives

Developing the previously tested approach to the configurational and conformational analysis of cyclic chiral compounds based on a complex use of NMR spectra and molecular simulation, we determined the configuration 1R, 2R, 4R, 1S and conformational state of 2[1hydroxy1(4carbomethoxyphenyl) methyl]pmenthane3one, a minor product of the directed aldol reaction of (–)menthone with 4carbomethoxybenzaldehyde. The configurations of the cyclic chiral centers were determined by analysis of the spin–spin coupling constants of the protons of the cyclohexanone ring for the most probable conformations of alternative stereoisomers. The S configuration of the C (1) exocyclic chiral center was established from the different orientation of the benzene ring relative to the cyclohexanone fragment in alternative stereoisomers, as shown by semiempirical quantumchemical simulations (AM1 and PM3 methods), and from the observed difference in proton chemical shift between the examined hydroxyketone and the model (+)isomenthone (1R, 4Rdiastereomer).     

Optical Nanocomposite Planar Waveguides Doped with Rare-Earth and Noble Metal Elements

The present paper is focused on multilayer Er³⁺-doped silica-titania planar waveguides, co-doped with silver, which were prepared by spin-coating on silica glass, or buffered single crystal silicon substrates. The single layer thickness (0.4 m) and refractive index (1.60–1.63) were measured by spectroscopic ellipsometry at 715 nm. The thickness of the waveguides (measured by mechanical profilometry) was 1 m and their optical propagation losses were measured at different laser wavelengths (488 nm, 514 nm and 633 nm), exhibiting an approximately Rayleigh-like behavior. The thermal precipitation of silver nanocrystallites was achieved, both in air and under a controlled atmosphere (dry nitrogen) and these were characterized by visible absorption spectroscopy, which clearly showed the development of a plasmon absorption band near 415 nm, by X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The Er³⁺ metastable level lifetimes for the emission at ca. 1.54 m were found to be ca. 4–6 ms, for Er³⁺ concentrations varying between 0.2–2.0 mol% (or (0.4–4.4) × 10²⁰ ions/cm³), but no significant variation was observed with the Ag concentration added (up to 2.5 mol%).     

A new inorganic-organic polymer for the passivation of thin film capacitors

Inorganic-organic polymers with barrier properties against water vapor, excellent electrical data (3, 2, R _D>10¹⁶ cm, E _D up to 400 V/µm) and good adhesion to various substrate materials have been developed. Tailored modifications of these materials provide an excellent protective coating for thin film capacitors. Several mm thick, expensive, encapsulations could be replaced by thin coatings (up to 10 µm). The polymer coating allows the use of thin film chip capacitors in surface-mount technology. As a measure for the efficiency of the coating, the capacitance decrease under controlled humidity has been used. The influence of the material composition, the type of catalyst during sol-gel processing and the curing conditions have been studied. Adhesion and water vapor permeation properties of the polymers and rheological properties of the coating solutions have been investigated. A protective coating is developed, which increases the withstandness of capacitors against humid conditions (90°C, 100% rel. humidity) by a factor of about 30 (compared to uncoated capacitors) and shows no crack formation during thermal cycling.     

Enhancing electrochromic contrast and redox stability of nanostructure polypyrrole film doped by heparin as polyanion in different solvents

Heparin‐doped polypyrrole (PPy‐Hep) and ‐doped polypyrrole (PPy‐ClO₄) films are synthesized onto FTO‐coated glass electrode in a potentiostatic electrochemical process with the aim of producing uniform, transparent, and adherent coating. The resultant polymers are characterized via cyclic voltammetry, scanning electron microscopy (SEM), and UV–vis absorption spectroscopy. SEM study indicates that the PPy‐Hep film to be composed of a continuous interlinked network of quasi spherical grains (50–80 nm in dimensions). The electrochromic properties of PPy‐Hep and PPy‐ClO₄ polymer films are compared to spectroelectrochemistry and switching studies. The effect of different solvents (water, propylene carbonate, and acetonitrile) on the electrochromic features of electropolymerized polymers has been investigated, and we find a very significant solvent effect. PPy‐Hep film exhibits switching time of 1 s and the maximum transmittance contrast (ΔT%) is 48% at 800 nm in water. In addition, presence of Hep causes drastic enhancement of electro‐optical stability of PPy. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3365–3371     

Synthesis and electrochromic properties of polyimides with pendent benzimidazole and triphenylamine units

Five novel near-infrared electrochromic aromatic polyimides(PIs) with pendent benzimidazole group were synthesized from 4,4'-diamino-4'-(1-benzylbenzimidazol-2-yl)triphenylamine(named as DBBT) with five different dianhydrides via two-step polymerization process, respectively. The maximum UV-Vis absorption bands of these PIs locate at about 335 nm for solid films due to the π-π* transitions. A reversible pair of distinct redox peaks, that were associated with a noticeable color change from original yellow to blue, was observed in the cyclic voltammetry(CV) test. A new absorption peak emerged at 847 nm in near-infrared(NIR) region with increasing voltage in UV-Vis-NIR spectrum, which indicates that PI can be used as NIR electrochromic material. These novel PIs have good electrochemical stability, appropriate energy levels for the highest occupied molecular orbital(HOMO) and the lowest unoccupied molecular orbital(LUMO), in the range of-5.17 e V to-5.20 e V and-2.14 e V to-2.26 e V(versus the vacuum level) determined by cyclic voltammetry method. These values basically consisted with the results of quantum chemical calculation. These polyimides can be used as novel electrochromic and hole transportation materials.     

Modeling of the Electronic Absorption Spectra and Photoionization of Scandium and Titanium Tris(acetylacetonates) by the DV-XαMethod

In order to interpret the electronic absorption spectra of titanium tris(-diketonates) and to establish the correlation between the ionization and excitation energies, the oscillator strengths and energies and the ionization energies for the model complexes M(Mal)₃(Mal is deprotonated malonodialdehyde, M = Sc, Ti) were calculated in the transition state approximation of the DV-Xmethod. The good agreement between the calculated photoelectron spectra and the experimental data and the correlation found between two types of excitation justified the assignment of the experimental absorption bands to the electronic states of Ti(Acac)₃.     

The Degradation of the Active Medium of an Argon Fluoride Discharge Lamp with a Noncorrosive Gas Mixture

The results of a spectroscopic study on the degradation of the active medium of an ArF electric-discharge lamp with the He–Ar–SF₆ working mixture (p 100 kPa) and pumped by a transverse space discharge are presented. Plasma radiation spectra were studied over the range 190–780 nm at different stages of degradation of the working mixture, and the dynamics of emission from the inert gases, as well as the products of sulfur hexafluoride degradation in the plasma, were determined. The ArF(B–X) emission band at = 193 nm was observed when the number of discharge pulses was 10³, whereas the quite effective formation of excited sulfur molecules, which decomposed producing emission bands in the spectral region of 260–550 nm, took place at n 10⁴.     

Fabrication of PZT/CuO composite films and their photovoltaic properties

In this paper, we reported the design and preparation of a double-layer antireflective (AR) coating, which possessed relatively high transmittance at 351, 527, and 1053?nm. The refractive indices and film thicknesses of the under layer and upper layer of the simulated AR coating were determined as 1.27, 95?nm and 1.18, 106?nm, respectively. The under layer of the double-layer coating dip-coated from a mixture of base-catalyzed and acid-catalyzed silica sols had a refractive index of 1.27. The upper layer fabricated by the deposition of methylated silica nanoparticles by simply adding methyltriethoxysilane into the base-catalyzed silica sols possessed a refractive index of 1.18. The hydrophobicity of coatings could be dramatically improved with the water contact angle increasing from 23.4° to 150.0°, and the refractive indices of the pure base-catalyzed silica coatings were easily decreased from 1.20 to 1.12 through the surface treatment of silica nanoparticles. Thus, we have successfully prepared a double-layer AR coating, which had a high transmittance of 99.8%, 96.1%, and 99.7% at 351, 527, and 1053?nm, respectively.

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Quantitative electron-probe microanalysis of light elements: Determination ofa-Si∶C∶N∶O∶H insulating films

Amorphous SiCNOH films (1–3 m) are studied by EPMA after deposition of gold (1–5 nm) as a conductive coating. Its influence on thek-ratios (X-ray intensity relative to an uncoated standard) of silicon, carbon, nitrogen and oxygen is described as a linear function of the simultaneously determinedk-ratio of gold. Thek-ratios representing the uncoated specimen are obtained by extrapolation and, in combination with the PAP matrix correction model, quantitative EPMA can be performed with an analytical error of 2–5%, as it is demonstrated by samples of SiC, Si₃N₄ and SiO₂. No systematic shift of the concentrations is observed for layers ofa-SiCNOH determined at various electron energies of 5–12.5 keV. Hydrogen is calculated by difference and the concentrations prove to be a useful estimate in agreement with the results of chemical analysis. Si-K/Si-K spectra recorded on organo-silicon films and binary silicon compounds point out significant differences concerning the formation of Si-C, Si-N and Si-O chemical bonds.     

Preparation of Core/Shell Structure of α-Al(OH)3-SiO2 by Heterogeneous Nucleation-and-Growth Processing

In order to solve the difficult problem of heterogeneity of different components in the procedure of ceramic preparation, a novel processing (heterogeneous nucleation-and-growth processing) was used to prepare homogeneous distribution powders. Composite coating particles consisting of alpha aluminum hydroxide (-Al(OH)₃) cores (average particle size 0.42 m) with outer homogeneous amorphous silica layer are prepared by heterogeneous nucleation-and-growth processing. Effects of silica content in composite coating particles versus concentration of silicon tetraethoxide (TEOS), pH value, time and temperature are studied. The homogeneous amorphous silica layer on cores is confirmed by X-ray diffraction, transmission electron microscopy and zeta potential measurement.     

Photoluminescence of osmocene and decamethylosmocene

Osmocene (and decamethylosmocene) is characterized by a lowest-energy ligand field triplet which occurs at _max=372nm (374nm) in absorption and 567nm (572nm) in emission. This orange–yellow phosphorescence is rather intense at 77K but is also visible at r.t.     

Preparation of self-assembled fluorinated molecular aggregates, fluorescein nanocomposites: an extremely enhanced light absorption in nanocomposites

Self-assembled fluorinated molecular aggregates formed by fluoroalkyl end-capped N-(1,1-dimethyl-3-oxobutyl)acrylamide oligomers, N,N-dimethylacrylamide oligomers, and acrylic acid oligomers in methanol could selectively recognize fluoresceins as guest molecules to form a new class of fluorinated aggregates-fluorescein nanocomposites. These fluorinated fluorescein nanocomposites that are obtained exhibit an extraordinarily enhanced light absorption (_max ca. 440 nm) compared to that (_maxs 452, 480 nm) of the parent fluorescein in the absence of fluorinated aggregates.     

Acetylsevedine fromKorolkowia sewerzowii

The epigeal part ofKorolkowia sewerzowii Regl. has yielded a new alkaloid — acetylsevedine with mp 189°C (with foaming), []_D –36.6°, C₂₉H₄₇NO₄. On the basis of the IR, PMR, and mass spectra of acetylsevedine, of the products of its transformation, and also a passage to the known alkaloid sevedine, the structure of 6-acetoxy-3, 14-dihydroxycevanine has been established for acetylsevedine.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 352–353, May–June, 1986.     

Synthesis and near infrared electrochromic properties of metallodithiolene complexes

Four metallodithiolene complexes[4,8-bis(octyloxy)-1,3,5,7-tetrathia]?di[1,1′-bis(diphenylphosphino)ferrocene?palladium(II)](3),[4,8-bis(octyloxy)-1,3,5,7-tetrathia]di[1,3-bis(diphenylphosphino)propane?nickel(II)](4),[4,8-bis(octyloxy)-1,3,5,7-tetra-thia]?[1,1′-bis(diphenylphosphino)ferrocene?palladium(II)]?[1,3-bis(diphenylphosphino)propane·nickel(II)](5)and di[4,8-bis(octyloxy)-1,3,5,7-tetrathia]?[1,1′-bis(diphenylphosphino)ferrocene?palladium(II)]?nickel(II)(6)were synthesized and the near-infrared(NIR)electrochromic properties were studied.The spectroelectrochemical spectra and the electrochromic parameters such as optical contrast,switching time,optical density change,electrochromic efficiency and optical attenuation of complexes 3–6 were investigated in detail.The symmetric binuclear complex 4 showed relatively high electrochromic efficiency of63.0 and 75.4 cm~2/C both in the two oxidation states.The complexes exhibited excellent electroactive/electrochromic stability characterized by chronoamperometry(4000 cyclic switches).     

12-Tungstosilicic Acid (12-TSA) as a Tungsten Precursor in Alcoholic Solution for Deposition of xWO3(1 − x)SiO2 Thin Films (x ≤ 0.7) Exhibiting Electrochromic Coloration Ability

The preparation of stable alcoholic solution of tungstosilicic acid and silicon alkoxide, which can be used for xWO3 (1 – x)SiO2 thin film deposition by dipping, is described. After thermal treatment at temperatures 440 to 500°C in nitrogen films with x higher than 0.6 exhibit electrochromic coloration ability. After coloring the film by H+ imtercalation (by contact with an indium wire trough a drop of aqueous solution of H2SO4) the luminous transmittance (illuminant D65, wavelength range from 380 to 780 nm, summation at 10 nm intervals) of glass coated with 90 nm thick xWO3(1 – x)SiO2 thin film decreases from 71.7 to 28.6% and the IR reflection increases to over 30%. At the same time the surface resistance decreases from a few M/ to about 400/. The thermal decomposition of tungstosilic acid embedded in alkoxy-hydroxy-oxy-silicon matrix is investigated with DTA, TGA, XRD and FTIR spectroscopy.     

Sensitization of Niobium Pentoxide Thin Films by cis-Dithiocyanate (2,2-bipyridyl-4,4′dicarboxylic acid) Ruthenium(II) Complex

The sensitization caused by the adsorption of a ruthenium complex in a niobium thin film (d < 300 nm) was analysed by photoelectrochemical measurements. The films were coated on a indium-tin-oxide (ITO) conductor glass by a dip-coating technique. The non-sensitized film had only photoelectrochemical current in the UV region (i 40 nA). The sensitization of the film by cis-dithiocyanate (2,2-bipyridyl-4,4dicarboxylic acid) ruthenium(II) complex altered the shape of the non-normalized action spectrum with the presence of photoelectrochemical current in the visible range ( 400 nm). This photoelectrochemical current (i 70 nA) was associated with electron injection into the niobium pentoxide conduction band due to metal-to-ligand charge-transfer (MLCT) of the ruthenium complex. The shape of the action spectrum in the UV range ( 400 nm) changed with the application of an electric potential to the film surface and the photoelectrochemical current associated with the ligand-to-metal charge transfer of niobia film decreased for higher ruthenium concentration.     

Room-Temperature Mirror Preparation Using Sol-Gel Chemistry and Laminar-Flow Coating Technique

The CEA/DAM megajoule-class pulsed Nd:glass laser devoted to Inertial Confinement Fusion (ICF) research will require 240 cavity-end mirrors. The approved laser design necessitates 42-cm × 46-cm × 9-cm highly-reflective (HR)-coated substrates representing more than 50 m² of coated area. Prototypes of these dielectric mirrors were prepared with interference quaterwave stacks of SiO₂ and ZrO₂-PVP (PolyVinylPyrrolidone) thin films starting from sol-gel colloidal suspensions (sols). Low refractive index material was based on nanosized silica particles and high refractive index coating solution was made of a composite system. The colloidal/polymeric ratio in the composite system has been optimized regarding refractive index value, laser damage threshold and chemical interactions have been studied using FT-IR spectroscopy. A deposition technique so-called Laminar Flow Coating (LFC) has been associated to sol-gel chemistry for HR laser damage-resistant sol-gel coating development. This novel coating method confirmed its main advantages compared to dipping or spinning processes: coating large flat square substrates at room temperature with small solution consumption, good thickness uniformity, weak edge-effects, induced stress-free coating, good optical properties and laser damage resistance fulfilling.     

Synthesis of Retro-γ-Ionols and the Corresponding-Ionones1

Both the direct² and the sensitized^3,4 photolyses of (E)-β-ionol (2) have been studied in some detail. In a preliminary publication⁵ we have indicated that direct photolyses of (E)-β-ionol (2) with λ = 254 nm yields (Z)-retro-γ-ionol (3) as the primary product; upon further irradiation 3 is converted into the corresponding (E)-isomer (4) which rapidly yields the bicyclic alcohol 5. A quantitative study revealed that the photoconversion of (E)-β-ionol with λ = 254 nm to 3 is about 10 times faster than the conversion of 3 into (E)-retro-γ-ionol.⁶ This rate difference thus allows the photosynthesis of 3.     

Fluorimetric determination of 1-naphthol and mixtures of carbaryl and 1-naphthol in micellar media

Summary The interaction of 1-naphthol with different types of anionic, cationic and non-ionic surfactants has been studied spectrofluorimetrically in order to obtain a sensitivity enhancement in the determination of this compound. At neutral pH, cetyl trimethyl ammonium bromide (CTAB) provides a 2-fold sensitivity enhancement of 1-naphthol and exhibits a weak interaction with carbaryl. In strong alkaline medium carbaryl is hydrolyzed to 1-naphthol and in the presence of CTAB micells, a 5-fold sensitivity enhancement and a limit of detection of 0.2 g·ml^–1 with a 101±3% percentage of recovery is obtained. These facts permit the development of an accurate method for the fluorimetric analysis of 1-naphthol and carbaryl mixtures, comprising the determination of the sum of both compounds (pH 12, 0.1% w/v CTAB, _em=449 nm, _ex=341 nm) and of the concentration of 1-naphthol (neutral pH, 0.4% w/v CTAB, _em=449 nm, _ex=312 nm).