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 atures.Samples'structure were inves...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 atures.Samples'structure were investigated by XRD,FTIR and FT-Raman spectroscopy.FIIR 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 phase.The pemittivity of complexes was found at much higher values than that of the ligand(pure urea),showing structure dependency.Furthermore,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 groups.Both relaxation peaks correspond to thermally activated because they were shifted to higher frequency with the temperature increase.The 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 bond.Novelty 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.展开更多
基金supported by National Research Centre(NRC),Cairo,Egypt.
文摘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 atures.Samples'structure were investigated by XRD,FTIR and FT-Raman spectroscopy.FIIR 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 phase.The pemittivity of complexes was found at much higher values than that of the ligand(pure urea),showing structure dependency.Furthermore,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 groups.Both relaxation peaks correspond to thermally activated because they were shifted to higher frequency with the temperature increase.The 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 bond.Novelty 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.
