Evaluating the Thermal Stability, Morphological and Temperature Effect on Electrical Conductivity, and Dielectric Properties of Curcumin Nano-Crystals

Abstract

The thermal structure and morphology of 1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione (curcumin) nanocrystals were investigated deploying thermogravimetric and field-emission scanning electron microscopy (FESEM), respectively. The mass loss was identified between 509-673 K. FESEM images of powder curcumin revealed a fluffy cotton-like morphology with a nearly spherical shape in nanoparticle scale. In addition, the AC conductivity and dielectric features of curcumin as a disk have been examined across a wide frequency range and at various temperatures. Jonscher's relation can be applied to interpret the frequency dependence of AC electrical conductivity. According to the behavior of frequency exponent S, the correlated barrier hopping model is the predominant mechanism. Indeed, the low values of activation energy endorsing the hopping mechanism. The findings show that the maximum barrier height estimated as 0.345 eV. In addition, the impact of frequency and temperature on the dielectric constant, ε', and dielectric loss, ε'', were inspected as was the complex dielectric modulus. According to KWW formula, the Kohlrausch exponent value was estimated as 0.57 at 313 K and rises to 0.67 at 393 K.