Santhakumari, N C; Vallabhan, C P G(Elsevier, May , 1992)
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Abstract:
D.C. and a.c. electrical conductivities, dielectric constant and dielectric loss factor in single crystals of ethylenediammonium sulphate, (H3NCH2CH2NH3)(SO4), have been measured axiswise as a function of temperature. Anomalous variations in all the above properties at 480 K indicate the occurrence of a phase transition in the above material at this temperature. The existence of such a phase transition is also confirmed by DSC measurements. Electrical conductivity results are analysed and the activation energies of conduction at different temperature regions have been evaluated from the logσ vs 103T−1 plot. Possible mechanisms for the electrical conduction process are discussed, the available results being in favour of a proton transport model.
Vallabhan, C P G; Thomas, J; Pillai, V N S; Nampoori, V P N(Springer, 1999)
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Abstract:
The electrical conductivity and thermal diffusivity of pristine and iodine doped vanadyl naphthalocyanine (VONc) were studied. In the pristine sample, the temperature dependence was very weak below 300 K. The increase in conductivity at higher temperature must be due to an enhancement in carrier density with increase in thermal energy. The electrical conductivity of VONc increased when doped with iodine. The behavior of VONcI indicated that considerable changes have occurred in the electronic environment of the molecule as a result of doping. Iodine doping enhanced the thermal diffusivity of VONc. The increase in thermal diffusivity of the iodine doped sample may be due to the disorder of iodine atoms occupying the channels in one dimensional lattices.