Temperature-Dependence of Electrical ...

The electrical conductivity () of some coordination biopolymeric cross-linked zirconium (IV)- and tin (IV)-alginate complexes in the form of circular discs has been measured as a function of temperature. The measured values of the electrical conductivities were found to be in the range of semiconductors. The Arrhenius plots of log ơ vs. 1/T showed a complex behavior where two main conduction regions separated by two transition parabolic zones were observed. The observed increment in ơ values at the early stages was explained by formation of free-radical intermediates involving metal ions of lower oxidation states, whereas the sharp increment in ơ values at the elevated temperatures was interpreted by the degradation of such intermediates formed to give rise to the metal oxides as final degradation products. The X-ray diffraction patterns indicated that the alginate complexes are amorphous in nature. Infrared absorption spectra revealed a sort of complexation among the polyvalent metal cations and the functional carboxylate and hydroxyl groups of alginate macromolecule. A suitable conduction mechanism was suggested and discussed in terms of the complex stability related to the coordination geometry.