Impedance, AC conductivity and electric modulus analysis of L-leucine L-leucinium picrate

In this paper, we report the measurements of impedance spectroscopy for the L-leucine L-leucinium picrate compound synthesized by slow evaporation technique at room temperature in the frequency and temperature ranges of 209 Hz - 1 MHz and 393-433 K, respectively. The Nyquist plots exhibited single semi-circular arcs which were well fitted to an equivalent circuit. The frequency dependence of the AC conductivity has been investigated using the Jonscher universal power law: sigma(ac)(omega) = sigma(dc) + A omega(s). The exponent s remains constant in the investigated temperature range and is almost equal to 0.62. Single relaxation peak is observed in the imaginary part of the electrical modulus, suggesting the response of grain. The close values of activation energies obtained from the analysis of hopping frequency, electric modulus and dc conductivity indicate that the transport in the title compound can be described through a simple hopping mechanism, dominated probably by the motion of L-leucinium cations. (C) 2015 Elsevier B.V. All rights reserved.