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Unveiling of the structural, optical and dielectric proprieties of cobaltite compound La0.57Nd0.1Sr0.18Ag0.15CoO3 for optoelectronic application
Authors: Benslimen, T.; Issaoui, H.; Brahmi, M.; Issaoui, F.; Dhahri, E.; Costa, B.F.O.; Nogueira, B.A.; Fausto, R.
Ref.: J. Mol. Struct. 1351(2), 144283 (2026)
Abstract: In this research, we focus on the structural, morphological, magnetic and dielectric properties of La0.57Nd0.1Sr0.18Ag0.15CoO3(LNSACO) compound synthesized by the sol-gel technique. The study by X-ray diffraction shows this compound crystallizes in the rhombohedral system, with R-3c space group. However, the XRD spectra reveal the existence of other peaks associated with the secondary phase of Co3O4 of space group Fd-3 m. The value of the optical band gap energy was determined from the variation of the absorbance as a function of the wavelength, this energy gap (Eg) of 1.46 eV. Electrical and dielectric characterizations of the material were performed using complex impedance spectroscopy in the frequency range from 100 Hz to 1 MHz and in a temperature range from 100 to 200 K. The conductivity spectra have been investigated by the Jonscher´s law sigma (omega)=sigma dc+A omega s with an increase in the frequency exponent (s) as the temperature increases. The imaginary part of the complex impedance (Z´´) frequency dependence was characterized by the appearance of a peak, which moves towards higher frequencies with the increase in temperature. The activation energy values obtained from both dc conductivity and the impedance (Z ´´) spectrum are found to be very similar. Hence, the relaxation process may be attributed to the same type of charge carriers. The Z ´ and Z ´´ versus frequency plots revealed the appearance of a semi-circular arcs and an electrical equivalent circuit of the type [(R1//CPE)(R2//C)] has been proposed to explain the impedance results.
