Raman scattering and alternative current conduction mechanism of the different phase transitions in [(CH3)3NH]CoCl3·2H2O

A comprehensive study of the dielectric and electric modulus properties of this compound was conducted using impedance spectroscopy in the frequency range of 100 Hz to 1.3 MHz and over the temperature range of 270 K to 335 K. The analysis of Nyquist plots revealed the presence of grains, grain boundaries and the electrode effects. The modulus plots were characterized by the presence of two peaks associated with grains and grain boundaries. The temperature dependence of the electrical conductivity (σg) and AC conductivity (σac) confirmed the phase transition. The AC electrical conduction in the [(CH3)3NH]CoCl3·2H2O compound underwent two processes attributed to a hopping transport mechanism: the correlated barrier hopping model in region I and the non-overlapping small polaron tunneling model proposed as a closely good model for region II.