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Mg-substitution effect on microstructure, dielectric relaxation and conduction phenomenon of Fe based Perovskite nanomaterials

Authors: A. Bougoffa, A. Benali, M. Bejar, E. Dhahri, M.P.F. Graca, M.A. Valente, L. Bessais, B.F.O. Costa

Ref.: J. Alloys Compd. 856, 157425 (2021)

Abstract: In this work, we have investigated the electrical and dielectric properties of the Mg doped perovskite (La0.8Ca0.1Pb0.1Fe1-xMgxO3 (x=0.0, x=0.1 and x=0.2)) using the electrical impedance spectroscopy in the temperature range of (200–320 K). The crystal structure evaluated by X-Ray diffraction proved an orthorhombic structure of all the studied compounds with a Pbnm space group. Impedance fitting based on an equivalent circuit and the M” fitting confirmed the existence of two relaxation phenomena attributed to grains and grain boundaries contributions. The study of the dc electrical conductivity proved that all compounds followed the variable range hopping (VRH) model at low temperature and the Arrhenius model at high temperature range. From conductivity analysis and the temperature dependence of the Jonscher’s power low exponent, we noted an alternation of correlated barrier hopping (CBH) and non-overlap small polaron tunneling model (NSPT) conduction processes at the studied temperature range. The relaxation phenomenon for both contributions and the deduced activation energies were found to be sensitive to the Mg composition; for the grain contribution, a minimum activation energy value was recorded for x = 0.1 compound and increased for suplementary Mg content. While, for grain contribution the activation decreases with the increase in Mg ion concentration. Concerning the evolution of the magnetization versus temperature, it was measured to investigate the effect of the Mg amount on the magnetic behavior of the prepared compounds under the studied temperature range.

DOI: 10.1016/j.jallcom.2020.157425