Analysis of conduction mechanism in lamellar double hydroxide by impedance spectroscopy

Zn-Al layered double hydroxides (LDHs) were prepared; using the co-precipitation method; with Cl- and NO3- interlayer anions and with two Zn/Al ratio (R=2 and R=3). The structural evolution of these compositions was characterized by Riveted analysis on powder X-ray diffraction diagrams. Impedance measurements of these compositions were investigated in the frequency range [100Hz-1MHz] and in the temperature range 25 degrees C-90 degrees C. Cole-Cole plots in impedance spectra showed non-Debye relaxation. The temperature dependence of the relaxation times for all samples showed Arrhenius behavior, from which the activation energy was derived. The real part of ac conductivity spectra of these materials obeys Jonscher power law. The nature of variation of the electrical conductivity, and value of activation energy of different samples, suggest that the conduction process appear clearly related to the structural evolution of the interlayer domain.