摘要:

AbstractPolyaniline films have been grown in solutions based on acetonitrile or acetonitrile/nitromethane mixtures by galvanostatic, potentiostatic and cyclic voltammetry techniques. LiClO4or anilinium tetrafluoborate was used as a salt. With the latter, aniline was absent in some tests, since anilinium could act simultaneously as a charge carrier and a polymerising species. The film characteristics have been evaluated by cyclic voltammetry, impedance spectroscopy and SEM experiments. It has been found that the protons released by aniline (following oxidation) or anilinium can be made available to the g| wing chains if the protophilic character of the solvent is sufficiently low. In a 1/1 acetonitrile/nitromethane mixture the galvanostatic and potentiostatic techniques produce electroactive films of reduced resistance, especially if anilinium tetrafluoborate is present. These seem to be the best conditions for the synthesis.

ISSN:1057-9257    

DOI:10.1002/amo.860010602

出版商:John Wiley&Sons Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractElectroactive polyaniline films have been grown by galvanostatic, potentiostatic and cyclic voltammetry techniques in organic solutions based on LiClO4or anilinium tetrafluoborate as salts and acetonitrile or acetonitrile/nitromethane mixtures as solvents. After storage of these films in a 1 M H2SO4, Na2SO4aqueous solution, their stability was tested by cyclic voltammetry and impedance spectroscopy in this solution. Different levels of retention of the anodic charge have been found depending on the electrochemical technique and preparation solution. The impedance tests have revealed limited changes in the charge transfer resistance upon storage. This has been interpreted on the basis of a limited deactivation of the films, which in some cases would instead experience physical changes. Confirmation of this assumption was obtained via an SEM experiment.Films prepared by cyclic voltammetry in the above acidic solution and stored in acetonitrile‐or propylene‐carbonate‐based electrolytes show major degradation processes, as evidenced by the appearance of quinone‐like compounds and the marked increase in the charge transfer resistance.Finally, films prepared by different electrochemical techniques in acetonitrile‐based solutions and stored in LiClO4‐acetonitrile reveal moderate degradatio

ISSN:1057-9257    

DOI:10.1002/amo.860010603

出版商:John Wiley&Sons Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractA new chemical sensing system using an electrical oscillator has been developed. This sensing system measures the electrical ‘non‐linearity’ at the surface of an electrode immersed in a test solution: a sinusoidal voltage is applied to the electrode and the higher harmonics of the output current are obtained by Fourier transformation. This sensing system has been used to detect and quantify surfactant molecules in solutions. The relative intensityP2/P1of the peaks of the second (P2) and first (P1) harmonics in the output current was found to be linearly correlated with the logarithms of the concentrations of cationic surfactants such as cetylpyridium bromide (CPB) and cetyl‐N,N,N‐trimethylammonium bromide (CTAB), but not with those of the anionic surfactant sodium dodecyl sulfate (SDS) or the neutral surfactant Triton X‐100. The reproducibility of this sensing system was shown to b

ISSN:1057-9257    

DOI:10.1002/amo.860010604

出版商:John Wiley&Sons Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe composition of the gaseous phase during pyrolytic laser‐induced chemical vapour deposition (LCVD) of aluminium from trimethylaluminium (TMA) was determined. The analysis was carried outin situby means of a quadrupole mass spectrometer (QMS) in a closed reaction cell. The decomposition of the aluminium alkyl was induced by a copper bromide vapour laser on the surface of (111) silicon monocrystalline wafer at 0.22 GW m−2average power density, 120 μm s−1scanning speed and 100 Pa (1 mbar) partial pressure of TMA. The detected gaseous products of the pyrolysis of TMA were ethane, ethylene, methane and hydrogen. The presence of ethane and ethylene was probably due to the unconventional way of decomposition caused by pulsed laser irradiation. The mass peak dynamics of the created pyrolytic products atm/e= 28, 16 and 2 indicated significant production of ethane + ethylene, methane and hydrogen in the ratio 1:

ISSN:1057-9257    

DOI:10.1002/amo.860010605

出版商:John Wiley&Sons Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe application of liquid crystalline siloxanes consisting of pentamethylhydrocyclosiloxane cores with attached cholesteryl‐, biphenyl‐ and photochromic spiropyran‐based mesogens as reversible optical data storage materials is demonstrated by grating formation with an argon ion laser beam operating in the UV and visible regions. Erasure of the gratings with heat or visible radiation was pos

ISSN:1057-9257    

DOI:10.1002/amo.860010606

出版商:John Wiley&Sons Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractA laminar flow low‐pressure chemical vapour deposition (LPCVD) system (LAM IntegrityTM) has been used to deposit tantalum pentoxide (Ta2O5) from Ta(OEt)5films in the presence of oxygen (O2) at 470 °C at a typical deposition rate of 4 nm min−1. Uniformities of700 °C. The transmission electron microscopy (TEM) results on crystallisation behaviour were supported by X‐ray diffraction data. The electrical properties of the Ta2O5films have been characterised using MIS (metal/insulator/silicon) capacitor structures. Leakage values of30 have been measured. The electrical properties reveal the potential use of Ta2O5as a storage capacitor dielectric in 64 and 256 Mbit DRAM (dynamic random

ISSN:1057-9257    

DOI:10.1002/amo.860010607

出版商:John Wiley&Sons Ltd.    

年代:1992

数据来源: WILEY

ISSN:1057-9257    

DOI:10.1002/amo.860010601

出版商:John Wiley&Sons Ltd.    

年代:1992

数据来源: WILEY