Enhanced dielectric properties of zinc doped bentonite composites: an effect of cobalt doping concentrations and tight binding calculation

Abstract

In this study we have successfully synthesized undoped and Zn and Co incorporated bentonite samples. The amount of Zn was kept constant while as Co amount was varied. All the synthesized samples were characterized using x-ray diffraction analysis which confirms the predominant presence of montmorillonite in all the samples thus confirming successful formation of bentonite. Similarly, EDX analysis confirms successful incorporation of Zn and Co in Ben sample. The analysis of the dielectric properties of the produced samples was successfully carried out, and the frequency dependence of the dielectric constant and dielectric loss was explored. According to the results, all the samples exhibit considerable dielectric dispersion at lower frequencies, whereas steady dielectric constant and modest dielectric loss are shown at higher frequencies. The effect of Zn, Co incorporation and temperature dependence of dielectric behaviour of all the samples was also analysed and it was observed that at low temperatures undoped Ben samples showed high dielectric constant while as at higher temperatures the incorporation of Zn and Co enhances the dielectric constant of as prepared sample. Similarly, the variation of conductivity of as prepared samples with frequency and temperature was analysed and it was observed that all the samples show similar conduction behaviour and follows correlated barrier hopping type of conduction. The real and imaginary part of electric modulus as a function of frequency was also analysed. Further, theoretical analysis showed considerable change in HUMO and LUMO which is considered as a main reason responsible for change in dielectric characteristics of Ben and Zn/Co incorporated samples. From this study it was observed that the incorporation of metal ions into the layered bentonite improved the dielectric properties at high temperature thus this study provides a new insight into the development of new dielectric materials which could be used under high temperature operation conditions.

Keywords

• Bentonite
• Dielectric constant
• Dielectric loss
• Conductivity
• Electric modulus
• Metals