RESUMO
In the present research, polycrystalline samples of La0.5Sm0.2Sr0.3Mn1-x Cr x O3 are prepared using the self-combustion method. Then, we have studied their crystalline structure, and dielectric and electrical properties. The X-ray diffraction study shows that all the samples exhibit a single phase with orthorhombic structure (space group Pnma). The studied samples were also characterized by complex impedance spectroscopy in a wide range of temperatures and frequency. AC conductivity analyses are used to study the transport property of the investigated samples. These analyses indicate that the conduction mechanism is strongly dependent on temperature and frequency. It is also found that the conductivity decreases with Cr concentration. Complex impedance analysis confirms the contributions of grain and grain boundaries in the conduction mechanism. Finally, the impedance spectra, characterized by the appearance of semicircle arcs at different temperatures, were well modeled in terms of equivalent electrical circuits to explain the impedance results.
RESUMO
This work reports an analysis of the dielectric properties of reduced graphene oxide mixed into epoxy resin, diglycidyl ether of bisphenol A, in the frequency range 10[Formula: see text]-10[Formula: see text] Hz and over the temperature range of 300-400 K, using impedance spectroscopy. For this study, a series of samples were prepared with various filler contents. Using the electric modulus formalism, it has been found that these composites exhibit below and above the percolation threshold [Formula: see text] a critical behavior of the dielectric relaxation phenomenon due to the single [Formula: see text]-relaxation, which is associated with the glass-rubbery transition of the epoxy matrix above the glass transition temperature. The Cole-Cole model of dielectric relaxation was used for modeling the relaxation processes from which we extract the relaxation parameters. The obtained relaxation parameters suggest a behavior close to single relaxation time.
