Structural investigation, thermal analysis and AC conduction mechanism of thermally evaporated alizarin red S thin films

The differential scanning calorimetric (DSC) and the thermogravimetric analysis (TGA) of alizarin red S (ARS) in the powder form were investigated. Subsequently, the structural studies of thermally evaporated ARS thin films of were performed using the Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD) and the transmission electron microscope (TEM). Furthermore, the dielectric properties and alternating current conductivity, σac, of ARS thin film in the frequency range 100 Hz–5 MHz through the temperature range 303–393 K were investigated. The activation energy, ΔEac, was found to decrease as the frequency increases. Moreover, both of experimental and theoretical results of the frequency exponent, S, and σac as a function of temperature outweigh the overlapping large polaron tunneling model (OLPT) for explain the conduction mechanism for ARS thin films. Also, the Cole–Cole diagram for dielectric modulus and the complex impedance at different temperatures were investigated.