Abstract
Based on commercial bentonite (bento) and two metal precursors, including NiCl(2)and CoCl2, diverse series of composites were prepared by incipient wet impregnation. The prepared composites were characterized by X-ray diffraction, scanning electron microscopy and energy-dispersive X-Ray spectroscopy. X-ray diffraction studies show that the crystallite size decreased as increasing the wt. % of cobalt. Moreover, the presence of Co in the EDX spectra for all bento concentrations, suggests its successful incorporation and probably the formation of Ni-Co oxide. The dielectric constant epsilon ', the dielectric modulus (M ', M '') and the ac conductivity (sigma(ac)) were also studied. It was found that epsilon ' decreases with frequency in all samples, a clear dielectric alpha relaxation observed from dielectric loss M ''. sigma(ac)decreases by increasing Co content and the conduction mechanism is correlated barrier hopping (CBH). sigma(ac)(T) is thermally activated and the activation energy Ea decreased with increasing Co content.