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.