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  • Author or Editor: M. Abou Sekkina x
  • Chemistry and Chemical Engineering x
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Stoichiometrically adjusted antimony triselenide and antimony tritelluride semiconductors were carefully prepared for the first time. Numerous measurements were carried out, involving X-ray diffraction analysis, true density, thermogravimetric analysis and the temperature-dependence of the magnetic susceptibility. The results obtained indicated that antimony triselenide and antimony tritelluride polycrystals possess mass susceptibilities of −0.361×10−6 and −0.386×10−6 C.G.S., respectively. The results are discussed on the basis of electronegativity difference, partial ionicity of the bond, and bond strength.

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In the present manuscript, freshly prepared and also pure chemical grade (BDH) antimony trioxide specimens were investigated. Numerous measurements were carried out on these specimens, comprising chemical, spectral and X-ray analyses, pycnometric and X-ray density measurements and observations of the behaviour of the dielectric constant and dielectric loss factor (∈′ and ∈″) as functions of temperature and frequency. The results obtained gave values of 12.4 and 10 for the dielectric constant for the freshly prepared and commercial antimony trioxide specimens, respectively. The results were compared in correlation with the phase constitution and degree of compactness for both specimens. Finally, the data are discussed on the basis of the interactions of the field frequency and temperature with the electric dipoles and electronic polarization of the test specimens.

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Abstract  

Various samples of different substituted Laferrites La1–xSmx1 (Fe1–x2Bx2)O3 have been prepared by the usual ceramic procedure and firing technique. On these samples, numerous measurements have been performed, namely, thermogravimetric analysis (TGA), differential scanning calorimetry, the temperature dependence of electrical conductivity before and after -absorbed dose (4.5×107 rad) and the temperature dependence of dielectric constant. Results obtained were explained, interpreted and discussed in detail on the basis of interaction of the dopant cations and ionizing radiation with La-ferrite lattice. Furthermore, the thermal stability, activation energy and energy gap for semiconduction of the investigated ferrites were evaluated before and after -absorbed dose (4.5×107 rad). Finally, the activation energy for -radiation induced carrier liberation in La-ferrites was evaluated for the first time.

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A systematic study was made of the relative stability and various phase changes which take place when elemental compound and mechanically mixed semiconductors are heated. These were chalcogens, calcogenides and mixtures of the two. The interest in the present investigation is due to the useful application of the prepared materials in the transistor, radar, rectifier and other electronic industries. Thermogravimetry and differential thermal analysis were carried out in air in the temperature range 20–830°. The results led to the conclusion that the degree of stability of the mechanically mixed semiconducting components is much higher than that of either elemental or compound semiconductors. The results were discussed on the basis of the electronegativity differences and oxygen affinities of the non-metallic components. The thermal stability ranges were evaluated in each case for the materials investigated, for their subsequent physical measurements and their suitability for the production of semiconducting devices.

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Mechanism of thermal dehydrochlorination

o-Hydroxyacetophenone Girard-P hydrazone transition metal cation chloride complexes

Journal of Thermal Analysis and Calorimetry
Authors: M. M. Abou Sekkina and M. R. Salem

Co(II), Ni(II), Cu(II) and Zn(II) complexes ofo-hydroxyacetophenone Girard-P hydrazone were prepared by using the organic ligand and the corresponding transition metal chlorides. The protonation and formation constants were evaluated for the organic ligando-hydroxyacetophe-none Girard-P hydrazone and its transition metal complexes, respectively. The thermal behaviour of the test materials was established by means of DTA. Their semiconducting parameters were evaluated through DC-conductivity measurements, and their thermodynamic parameters were evaluated, assigned and interpreted. The mechanism of thermal dehydrochlorination of the metal chloride complexes was proposed.

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Several samples of Nb2O5-doped Bi2O3 and Y2O3-doped Bi2O3 were carefully prepared and sintered at 700° for 3 hours. Extensive measurements were carried out on these samples, including X-ray diffraction spectra, infrared absorption spectra and the temperature-dependence of the DC-electrical conductivity in the solid state. The results obtained were discussed, correlated and interpreted. Finally, the optimum compositions were established and recommended for doped-Bi2O3 in the electronics industry.

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Abstract  

Various samples of different substituted La-ferrites (La1–x 1Ax 1 (Fe1–x 2Bx 2)O3) have been prepared by the usual ceramic and high temperature sintering technique. On these specimens several measurements were carried out, namely, Cu–K X-ray analysis, true density, bulk density, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), IR absorption spectra, electronic absorption spectra and crushing strength before and after -radiation dose (4.5×107 rad). Results reported were promising, interpreted and discussed in detail on the basis of the interaction of -radiation and different dopant cations with La-ferrite lattices. Finally, a suggested lattice structure symbol was put forward.

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Several samples of Egyptian cotton fabric strips were subjected to various caustic mercerization conditions, varying in temperature and time. On these samples extensive measurements were undertaken, comprising X-ray diffraction, IR absorption spectra and the temperature-dependence of DC-electric conductivity.

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Thin CdSe films were prepared under vacuum at different glass substrate temperatures. The effects of substrate heating and temperature on the X-ray diffraction patterns, electrical, DC current-voltage characteristics and photovoltaic properties were investigated in detail. the results obtained were interpreted mathematically, which led to a hopping conduction mechanism. Valuable semiconducting parameters were evaluated for the thin films investigated, for their useful application in photovoltaic or solar cell industries: surface charge density (4.8×1012 cm−2), thickness of depletion layer (7.4×10−7 cm) and donor concentration (6.5×1018cm−3).

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