Nitrate-intercalated Mg 1−x Al x -Layered Double Hydroxides with different layer charges ( x ): Preparation, characterization, and study by impedance spectroscopy

Abstract Three phases of nitrate-intercalated Layered Double Hydroxides (LDH), based on magnesium and aluminum with different layer charges (x) (x = 0.2, 0.25 and 0.33), were synthesized by coprecipitation method, characterized by XRD, TGA, FTIR and analyzed by ICP and Impedance Spectroscopy. In this work, layer charge was found to have a strong influence on the lattice parameters, nitrate disposition, vibration bonds, thermal stability and particularly, electrical and dielectric properties that were investigated at room temperature under dry and wet air trough impedance spectroscopy. In fact, under dry air, electrical modeling showed three contributions attributed to the polarization of grains, grain boundary and electrode-sample interface, respectively, which were brought out by the frequency dependence of the imaginary part of complex modulus and complex impedance, the parameters of electrical equivalent circuit were determined and their dependence on the layer charge was also discussed. Ionic conductivity was found to depend on the layer charge and polarizing power, to follow double power law, and to show an increase of values about three orders of magnitude under wet air. Moreover, the dependence of dielectric constant and that of dielectric loss tangent on the layer charge and frequency were also presented and discussed.