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  • 1
    Electronic Resource
    Electronic Resource
    Effect of alkali ions on the electrical properties of the ferrite phase of cement clinker (1990)
    Springer
    Journal of materials science 1 (1990), S. 225-229 
    Details
    ISSN: 1573-482X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The ferrite phase of cement clinker was prepared from a mixture of pure oxides, and also after mixing this mixture with different weight percentages (1, 3, 10, 20 and 30%) of an alkali oxide (Na2O, MgO, SrO or BaO) at 1300° C. Electrical conductivity measurement (d.c.) was carried out from ice temperature to 570 K. It was found the alkali ions decreased the electrical conductivity with increasing alkali oxide content up to 3 wt% which was attributed to a change of C4AF structure from orthorhomic to tetragonal or monoclinic at elevated temperature, and the reduction of Fe3+ ions. Above 3 wt%, in the case of Na2O or BaO, the conduction increased. As MgO or SrO is similar to CaO the energy gaps ranged from 0.54 to 0.61 eV. The activation energy of pure C4AF is equivalent to 0.5 eV, as alkali ions were introduced this value changed according to th alkali type. This is considered as a quick method to assure the purity of the C4AF phase. This phase with alkali impurities behaves as a semiconductor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00696082
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  • 2
    Electronic Resource
    Electronic Resource
    Electrical and spectral studies of modified solid semiconductors (1993)
    Springer
    Journal of materials science 4 (1993), S. 43-46 
    Details
    ISSN: 1573-482X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Diazoaminobenzene shows semiconducting properties and a phenomenon of phase transition. The semiconducting properties arise as a result of high molecular resonance induced by intramolecular hydrogen bonding at the cliazo linkage. The phase transition is probably a consequence of thermal rotation into resolved cis and trans configurations; the frans form conducts electricity with a lower activation energy assisted by the molecular resonance. Thermal rotation into the more thermally stable cis form reduces the molecular resonance so that the resultant form conducts electricity with a higher activation energy. Unexpectedly, chelation with the favoured d-block element, Cu, reduces the electrical conductivity which is evidenced by a reduced electric dipole moment. Chelation appears to proceed favourably at the cis form, since the resultant complex conducts electricity with a similar high activation energy, a result of prohibited proton exchange. Restricted rotation in the Cu chelate explains conduction via a single phase. Consistent data from 1H-NMR, i.r. and u.v.—visible spectra do confirm the proposed structural interpretation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00226632
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  • 3
    Electronic Resource
    Electronic Resource
    Electrical transport as a function of temperature in urea and cobalt (III)-urea complex (1999)
    Springer
    Journal of materials science 10 (1999), S. 479-482 
    Details
    ISSN: 1573-482X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The temperature dependence of the electrical conductivity, and the voltage–current dependence of urea and its cobalt solid complex were determined. The values of the thermal activation energies indicate that the two compounds behave like semiconductors. The semiconducting properties of the ligand ‘urea’ are due to the electron delocalization via π-bond formation (C=NH,C=2 +) as well as the lone pair of electrons on the oxygen atoms of urea molecules. The high conductivity values of urea compared with those of its cobalt solid complex was suggested to be due to the ease of releasing the lone pair electrons on the oxygen atom as well as the hydrogen transfer during enol formation of urea molecules. The infrared, ultraviolet and visible absorption measurements were carried out to rationalize the mechanism of the conduction process in the investigated compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008967732440
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  • 4
    Electronic Resource
    Electronic Resource
    The electrical conductivity of some azine compounds (1991)
    Springer
    Journal of materials science 2 (1991), S. 11-13 
    Details
    ISSN: 1573-482X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Correlation of the molecular structure and thermal study of the electrical conductivity of benzaldazine (BA) and its NO2-derivatives were carried out. The values of the activation energies, obtained from the electrical conductivity measurements, as well as the energy gaps calculated from ultra violet (u.v.) and visible spectra obtained either in liquid or in solid forms indicate that all compounds behave like a semiconducting material. Both nπ*′s and ππ*′s were found to be the main sources participatiog in the cooduction processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00694997
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  • 5
    Electronic Resource
    Electronic Resource
    The photoconductivity of benzaldazine and its o- and p-hydroxy substituents (1991)
    Springer
    Journal of materials science 2 (1991), S. 133-136 
    Details
    ISSN: 1573-482X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The photoconductivity of benzaldazine (BA) and its o-, m- and p-hydroxy substituents has been measured. The voltage dependence is described by a linear term (ohmic) and a saturation term, the former of which dominates at low field strengths (up to 300 V). The temperature dependence of the photocurrent has been studied. The m-OH-BA has not shown any photoconductivity response.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00696286
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  • 6
    Electronic Resource
    Electronic Resource
    Temperature dependence of the electrical conductivity of Salicylaldazinate metal chelates (1992)
    Springer
    Journal of materials science 3 (1992), S. 124-126 
    Details
    ISSN: 1573-482X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A study of the temperature dependence of the electrical conductivity of Salicylaldazine and its metal complexes with the d-block elements Ni2+, Cu2+ and Zn2+, is correlated with molecular spectral data. The values of the activation energies obtained from the electrical conductivity measurements, as well as the energy gaps corresponding to the maximum absorption wavelengths in the region of ultraviolet and visible spectra, indicate the important role of chelation in producing the Salicylaldazine semiconducting properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00695728
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  • 7
    Electronic Resource
    Electronic Resource
    Electrical and spectrophotometric properties of charge transfer complexes of picric acid and some aniline derivatives (1993)
    Springer
    Journal of materials science 4 (1993), S. 109-112 
    Details
    ISSN: 1573-482X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The charge transfer complexes produced by the reaction between picric acid and some aniline derivatives were prepared. The prepared charge transfer complexes (CTC) were investigated using infrared and nuclear magnetic resonance spectroscopy aiming to throw more light on their molecular structure. It was proved that a proton transfer interaction takes place between PiOH and x-Ph.NH2 leading to the formation of PiO} and x-Ph.NH3 + ions. The normal π-π1 electronic interaction takes place by transferring an electron from the aniline ring to the picric acid. The semiconducting properties of the CTC were investigated. All the prepared complexes were proved to have a semiconducting character within the temperature range investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00180464
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  • 8
    Electronic Resource
    Electronic Resource
    Electrical conductivity and phase transition studies of some selected Congo red-metal complexes (1996)
    Springer
    Journal of thermal analysis and calorimetry 46 (1996), S. 1459-1466 
    Details
    ISSN: 1572-8943
    Keywords: complexes ; Congo Red-metal complexes ; electrical conductivity ; phase transition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The electrical properties of Congo Red dye (L) and its metal (M) complexes ofM∶L molar ratios of 1∶1 and 2∶1, whereM=Cr(III), Fe(lII), Cu(II), Zn(II), Zr(IV), Th(IV) and UO2(II), indicated semiconducting behaviour. The activation energies and electrical conductivities depend on the ionic charge of the metal chelates. The activation energies of 1∶1 metal complexes are greater than those of 2∶1 metal complexes. The conductivity data obtained are interpreted on the basis of the molecular structure of the Congo Red complexes. One phase transition was obtained during DTA study of Congo Red dye at 212°C. This phase transition may be due to the rotation of the two naphthalene rings and the N=N groups around the diphenyl group centre.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01979258
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  • 9
    Electronic Resource
    Electronic Resource
    Some aspects on the constitution of egyptian bagasse pith-phenol polycondensate resins. Part II. Spectroscopic analysisPart I: see the preceding paper (1988)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 39 (1988), S. 574-582 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Phenolharze, die durch Polykondensation von Phenol mit Furfural, Xylose, Glucose, Holocellulose, reinem Sodalignin und Bagassemark in saurem Medium hergestellt worden waren, wurden infrarotspektroskopisch untersucht. Im Infrarotspektrum des Sodalignin-Phenolharzes wird die Anwesenheit von aliphatischen Methyl-, Methylen-, Methin- und stark gebundenen OH-Gruppen nachgewisen. Deutliche Änderungen der Lage und Intensität der Banden werden in den Infrarotspektren von reinem Sodalignin bzw. Bagassemark und den entsprechenden Phenolharzen gefunden, was darauf hinweist, daß bei den Kondensationsreaktionen Abbauprozesse stattfinden. Die Infrarotspektren von Fraktionen des Bagassemark-Phenolharzes geben einen Einblick in die komplizierte Struktur dieser Verbindung. NMR- und UV- spektroskopische Untersuchungen bestätigen die IR-Ergebnisse.
    Notes: Infrared spectroscopic studies on some phenolic resins prepared by condensation of phenol with furfural, xylose, glucose, holocellulose, resistant cellulose, pure soda lignin, and bagasse pith, were carried out. The IR spectrum of soda ligninphenol resin proves the presence of aliphatic methyl, methylene, methine and strong bonded OH groups. Drastic changes in band position and intensity are observed in the IR spectra of pure soda lignin or bagasse pith and the respective phenolic resins, indicating that degradation processes could take place during the condensation reactions. The IR spectra of fractions of the bagasse pith-phenol resin give an insight in the complicated structure of this resin. NMR and UV spectroscopic studies confirm the IR data.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1988.010391011
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  • 10
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    Dual Maxwellian-Kappa modeling of the solar wind electrons: new clues on the temperature of Kappa populations (2017)
    EDP Sciences
    Details
    Publication Date: 2017-06-01
    Print ISSN: 0004-6361
    Electronic ISSN: 1432-0746
    Topics: Physics
    Published by EDP Sciences
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