Abstrait

Physical studies on mixed crystals of CoxNi3-x(C2O4)3.XH2O

W.A.A.Bayoumy

The temperature dependence of the dc-and ac-electrical conductivity  dielectric constant /, dielectric loss /, and molar magnetic susceptibility  forCoxNi3-x(C2O4)3.XH2O(x=0.0,0.57,1.15,1.83,2.40 and 3.0)was studied over a temperature range of 78-400K. The electrical conductivity() was found to increase with increasing the nickel content in the sample. An anomalous behavior in -T-1 relation is observed for all samples.At lower temperatures, the conductivity showed semimetallic behavior and the conduction is explained on the basis of an electron hopping near the Fermi level. At low temperatures, the ac-conductivity increases with frequency according to ac=As, where s has a value that lies in the range 0.30-0.63, depending on the temperature and the composition of the sample. The temperature dependence of both dielectric constant / and?dielectric loss  showed a maximumat the dissociation temperature of the sample. Magnetic susceptibility  showed antiferromagnetic character for all samples. The results have been correlated and discussed.