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

• Published in: Journal of alloys and compounds Vol. 856; p. 157425
• Main Authors: Bougoffa, Amira, Benali, A., Bejar, M., Dhahri, E., Graça, M.P.F., Valente, M.A., Bessais, L., Costa, B.O.F.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 05.03.2021; Elsevier BV; Elsevier
• Subjects: Activation energy; Conduction heating; Conduction process; Conductivity; Crystal structure; Dielectric properties; Dielectric relaxation; Electrical impedance; Electrical resistivity; Energy value; Equivalent circuits; Grain boundaries; High temperature; Impedance; Ion concentration; Low temperature; Magnesium; Magnetic properties; Magnetization; Nanomaterials; Perovskite; Perovskites; Physics; Temperature dependence; Conductivity; Perovskite; Magnetization; Impedance; Conduction process
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.157425

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. •Synthesis of pure nanometricLa0.8Ca0.1Pb0.1Fe1-xMgxO3 powder(x = 0, x = 0.1 and x = 0.2) sol gel route.•The study of dc-conductivity proves the VRH process at low temperature and the Arrhenius model at higher temperature.•The ac conductivity analysis proves an alternation of CBH and NSPT model in the investigated temperature range.•A theoretical modulation confirms the coexistence of the Antiferromagnetic and Ferromagnetic contributions.•10% of Mg2+ decreases the resistance and increases the conductivity which is beneficial to the gas sensing application.