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Structural and AC electrical properties study of solid metal urea complexes

Journal of Advanced Dielectrics 2018年第2期8卷 60-66页

作者： Ragab Mahani Saleh D.Mekky Badr A.El Sayed Gamal S.EL-Bahy azza ward Microwave Physics and Dielectrics Department National Research Centre 33 EL Bohouth St.(former EL Tahrir St.)Giza-Egypt-P.O.12622 Chemistry Department Faculty of ScienceAlazhar University Nasr CityCairoEgypt Spectroscopy Department National Research Centre 33 EL Bohouth St.(former EL Tahrir St.)Giza-Egypt-P.O.12622

The complexation of solid urea with(Co^(2+)),(Cu^(2+))or(Ni^(2+))ions has been studied by using dielectric spectroscopy technique over a wide frequency range at different temper ***'structure were investigated by XRD,FTIR and FT-Raman *** and Raman analy sis indicated that the urea coordinates with the metal atoms through the same oxygen-metal bond(O-M).Furthermore,XRD analysis showed that the samples have polycrystalline structure with single *** pemittivity of complexes was found at much higher values than that of the ligand(pure urea),showing structure ***,two relaxation peaks were observed in the dielectric loss spectra corresponding to the orientation po larization of urea molecule,and some parts of urea molecule may be NH2 *** relaxation peaks correspond to thermally activated because they were shifted to higher frequency with the temperature *** peak position for the low frequency relaxation peak was observed lht the same relaxation time(τ=7.6× 10^(-4) s),corresponding to the coordination mode through the same O-M *** of this work is the successful finding of the relationship between the crystalline phase,coordination mode and the dy namic molecular behavior of solid urea and its complexes using the dielectric spec-troscopy techn ique.

关键词： Urea complexes IR XRD permitivity

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Structural and dielectric properties of prepared PbS and PbTe nanomaterials

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Journal of Semiconductors 2018年第12期39卷 52-59页

作者： A.A.hzab azza A.ward G.M.Mahmoud Eman M.El-Hanafy H.El-Zahed F.S.Terra Solid State Physics Department Physical Research DivisionNational Research CentreGizaEgypt Microwave Physics and Dielectrics Department Physical Research DivisionNational Research CentreGizaEgypt University Girls College for Arts Scienceand EducationAin Shams UniversityHelioplesCairoEgypt

In this work, PbS and PbTe nanomaterials with various morphologies were synthesized by a hydrothermal method. The structural properties were investigated by using X-ray diffraction(XRD) and corresponding scanning electron microscopy together with their EDX analysis. Both the PbS and PbTe nanomaterials possess good polycrystalline structure. The crystallite size, determined from the XRD data, of PbS is 5 nm whereas the corresponding value of PbTe is 2.69 nm. SEM micrographs reveal that the prepared PbS nanomaterial has starshaped structures, micro-flowers, some cubes, and semi-dendrites, whereas PbTe has semi-flower structures. Additionally, the dielectric properties have been studied in a broad frequency range from 0.1 Hz up to 1 MHz at temperatures from 298-423 K. The real and imaginary parts of the complex dielectric constant ε' and ε" of PbTe are comparatively higher than those of PbS. Moreover, the dielectric data were analyzed on the basis of the electric modulus.

关键词： dielectric properties PbS PbTe SEM EDX electric modulus

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