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Electrical Conductivity Measurements (electrical + conductivity_measurement)
Selected AbstractsThermal and Electrical Conductivity Measurements on Aluminum FoamsMATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 4 2003N. Babcsán Abstract Metal foams are one of the most interesting types of materials although there is limited information concerning their thermal and electrical conductivity. Closed cell different density Alporas foams are investigated, which has one of the most homogeneous cell size distribution recently. Comparative method has been chosen to determine the thermal conductivity of the samples in the function of the temperature at 30, 100, 200, 300, 400, 500,°C. For measuring the electrical conductivity of aluminium foams a special low frequency eddy current measuring apparatus was used. The ratio of thermal and electrical conductivity was calculated and shown an increasing function by the density of the foams. [source] Measurement of electrical conductivity, differential scanning calorimetry and viscosity of starch and flour suspensions during gelatinisation processJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 15 2001Saiwarun Chaiwanichsiri Abstract Electrical conductivity measurements were applied to analyse the gelatinisation process of 12 starch or flour suspensions. The electrical conductivity of starch suspensions was found to increase upon gelatinisation because of the release of ions from starch granules. The initiation temperature of ion release, Ti, correlated well with the onset temperature in the DSC thermogram (R,=,0.868), while the completion temperature of ion release, Tf, correlated with the temperature at the start of viscosity increase (R,=,0.865). Thus Ti and Tf corresponded to the beginning and ending temperatures of gelatinisation respectively. The electrical conductivity measurement will be used as an on-line technique to monitor the whole process of starch gelatinisation. © 2001 Society of Chemical Industry [source] DC conductivity studies in K3Na(SeO4)2 single crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 7 2009G. Joseph Abstract DC electrical conductivity studies were carried out along the three crystallographic axes for Tripotassium sodium diselenate (K3Na(SeO4)2 or KNSe). Earlier studies of phase transition in this crystal show successive phase transitions at 334 K, 346 K, 730 K, and 758 K. In this paper we report the dc electrical conductivity measurements in the temperature region 303 K , 430 K along a, b and c , axes. An anomaly in conductivity was obtained around 341 K and another one around 333 K. These can be attributed as due to phase transitions in this crystal. A strong anomaly also has been observed along the c-axis and comparatively week one along a and b axes around 395 K for the first time. This can be due to newly observed phase transition in the crystal. DSC taken for the sample also shows endothermic peak supporting the occurrence of newly observed phase transition. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Conductive Nanostructures of MMX ChainsADVANCED FUNCTIONAL MATERIALS, Issue 9 2010Alejandro Guijarro Abstract Crystals of [Pt2(n -pentylCS2)4I] show a transition from semiconductor to metallic with the increase of the temperature (conductivity is 0.3,1.4,S,·,cm,1 at room temperature) and a second metallic,metallic transition at 330,K, inferred by electrical conductivity measurements. X-ray diffraction studies carried out at different temperatures (100, 298, and 350,K) confirm the presence of three different phases. The valence-ordering of these phases is analyzed using structural, magnetic, and electrical data. Density functional theory calculations allow a further analysis of the band structure derived for each phase. Nanostructures adsorbed on an insulating surface show electrical conductivity. These results suggest that MMX-polymer-based nanowires could be suitable for device applications. [source] Gas phase esterification of acetic acid with ethanol over MoO3 supported on AlPO4 and the effect of modification with phosphomolybdic acid and Ce4+ ionsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2003Abd El-Aziz A Said Abstract A series of AIPO4,MoO3 (APM) systems with various molybdena loadings (5,50) mol %, same modified with phosphomolybdic acid (PMA) and cerium ions, were prepared by an impregnation method and calcined at 400 °C, except for the samples modified with PMA which were calcined at 350 °C for 4 h. The catalysts were characterized by TG/DTG, XRD, IR spectroscopy, N2 adsorption and electrical conductivity measurements. The surface acidity and basicity of the catalysts were determined by adsorption of pyridine and the dehydration,dehydrogenation of isopropyl alcohol. The catalytic esterification of acetic acid with ethanol was carried out in a convention fixed bed reactor. The results clearly revealed that the catalyst with a composition of 10 mol % MoO3 (APM10) was the most active and selective catalyst for the production of ethyl acetate. Moreover, the yield of ethyl acetate increases on addition of PMA into APM10 while it decreases on the addition of Ce4+ ions. These results were correlated with structure, semiconductivity and the acid,base properties of the prepared catalysts. Copyright © 2003 Society of Chemical Industry [source] Synthesis and characterization of epoxidized polybutadiene/polyaniline graft conducting copolymerJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 12 2004F. R. De Risi Abstract In this article the synthesis and characterization of an elastomeric conducting material, obtained by grafting polyaniline (EB) on commercial cis -1,4-polybutadiene (PB), are described. PB was first partially epoxidized in chloroform solution using meta-chloroperbenzoic acid (MCPBA). The conducting polymer was then grafted to the activated polybutadiene (EPB) via the aminolysis reaction between the polyaniline NH2 terminal groups and the oxirane rings. The material so obtained (EPBPAN) and the epoxidized intermediate product were characterized by 1H NMR, 13C NMR, Fourier transform infrared, and ultraviolet,visible spectroscopy, thermal and mechanical analysis, and electrical conductivity measurements. The effect of the sample deformation on conductivity also was analyzed. The HCl doping of the EPBPAN film induced crosslinking reactions, generated by the acid cleavage of unreacted oxirane groups. The electrical conductivity of the doped material reached values of about 10,5 ,,1 cm,1. The key characteristics of our elastomeric conducting material are its simple synthesis, its starting as a commercial product, and the solubility of its undoped form in a common low-boiling organic solvent like chloroform. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3082,3090, 2004 [source] Optical and Electrical Properties of Amorphous and Nanocrystalline (La0.8Sr0.2)0.9MnO3 Thin Films Prepared from Low-Temperature Processing TechniqueJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2006Toshio Suzuki The results of a study on the optical and electrical properties of (La0.8Sr0.2)0.9MnO3 (LSM) thin films obtained by a polymeric precursor spin coating technique were presented. This method allowed preparation of optical quality thin films at annealing temperatures around 800°C. Amorphous and crystalline LSM thin films were studied by optical and electrical conductivity measurements. The energy-dependent absorption coefficients for the crystalline specimen were calculated from optical spectra and extra absorption was observed in the range of 1.8,2.5 eV with the exchange-gap excitation behavior in the 3,5 eV range. In comparison to the amorphous specimens, the electrical conductivity of the nanocrystalline specimen increased two to three orders of magnitude with decreasing activation energy. The charge carrier absorption model suggested an increase of the carrier concentration in the nanocrystalline specimen which may be a reason for the change in the electrical conductivity. [source] Ion irradiation and reduction effect on the conductivity and optical absorption of heavily MgO-doped LiNbO3 single crystalsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2005V.F. Pichugin Abstract The confirmation of MgNb defects in heavily MgO doped LiNbO3 single crystals were investigated through optical absorption, electrical conductivity measurements, optical spectroscopy with nanosecond time resolution, and Raman spectroscopy technique. An increase in the MgO concentration up to 10 mole% provides an essential change of the luminescence of LiNbO3, the appearance of a supplementary optical absorption band at the 1.1 eV, an alteration of the Raman spectra caused by the formation of (MgNb) defects, a shift of the edge of the supplementary optical absorption due to ion irradiation toward the shorter wavelength region as the MgO concentration increases. The effect of Ar+ ions irradiation on the conduction of the MgO doped LiNbO3 samples was studied. The important role of reduction in modification of the conducting properties of the ion-irradiated crystals was established. The increase of the MgO concentration leads to a decrease of the reduction efficiency. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effect of surface treatment for carbon nanotubes on morphological and rheological properties of poly(ethylene oxide) nanocompositesPOLYMER ENGINEERING & SCIENCE, Issue 10 2006Young S. Song Poly(ethylene oxide) nanocomposites filled with functionalized multi-walled carbon nanotubes are prepared and characterized using rheological and morphological measurements. This study investigates how the surface treatment of carbon nanotubes (CNTs) affects the CNT dispersion state. It is found that the nanocomposites have a higher effective volume fraction than the real volume fraction of the CNTs. The dispersion state of the CNTs is identified by using field emission scanning electron spectroscope and transmission electron microscope. The rheological findings indicate that there exists a percolated network structure of the CNTs in the nanocomposites, which was confirmed by electrical conductivity measurements as well as morphological observation. POLYM. ENG. SCI., 46:1350,1357, 2006. © 2006 Society of Plastics Engineers [source] Chemical and electrochemical synthesis of conducting graft copolymer of acrylonitrile with anilinePOLYMER INTERNATIONAL, Issue 9 2006S Hossein Hosseini Abstract A new conducting copolymer, polyacrylonitrile- graft -polyaniline (PAN- g -PANi), has been prepared by chemical and electrochemical methods from a precursor polymer. Poly[acrylonitrile- co -(acrylimine phenylenediamine)] (PAN- co -PAIPD) was synthesized chemically by reacting PAN with sodium 1,4-phenylenediamine salt. PAN- g -PANi was synthesized chemically using ammonium peroxydisulfate as the oxidant and p -toluenesulfonic acid in dimethylsulfoxide solution and adding aniline to oxidized PAN- co -PAIPD. Electrochemical polymerization was carried out by spin coating PAN- co -PAIPD on the surface of a Pt electrode, then the growth of the graft copolymer (PAN- g -PANi) in the presence of fresh aniline and acidic solution. The structures of the graft copolymer and PAN- co -PAIPD were characterized using UV-visible, Fourier transform infrared, and 1H and 13C NMR spectroscopies. The thermal properties of PAN- g -PANi were studied using thermogravimetric analysis and differential scanning calorimetry. Scanning electron microscopy (SEM) images showed that the morphology of PAN- g -PANi copolymer films was homogeneous. Electrical conductivity of the copolymer was studied using the four-probe method, which gave a conductivity of 4.5 × 10,3 S cm,1 with 51.4% PANi. SEM and electrical conductivity measurements supported the formation of the graft copolymer. Copyright © 2006 Society of Chemical Industry [source] | ||||||||||||||||||||||||||||