Effect of annealing temperature on structural, morphological and dielectric properties of La 0.8 Ba 0.1 Ce 0.1 FeO 3 per
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Effect of annealing temperature on structural, morphological and dielectric properties of La0.8Ba0.1Ce0.1FeO3 perovskite E. M. Benali1,2,3, A. Benali1,2,3,* , M. Bejar2, E. Dhahri2, M. P. F. Graca3, M. A. Valente3, P. Sanguino4, and B. F. O. Costa1 1
Physics Department, CFisUC, University of Coimbra, Rua Larga, 3004-516 Coimbra, Portugal Laboratoire de Physique Appliquée, Faculté Des Sciences, Université de Sfax, B.P. 1171, 3000 Sfax, Tunisie 3 I3N and Physics Department, University of Aveiro, 3810-193 Aveiro, Portugal 4 CEMMPRE, Mechanical Engineering Department, University of Coimbra, Rua Luís Reis Santos, 3030-788 Coimbra, Portugal 2
Received: 9 May 2020
ABSTRACT
Accepted: 30 July 2020
The La0.8Ba0.1Ce0.1FeO3 compounds were prepared by the auto-combustion route and annealed at two different temperatures to study their effect on the structural, morphological and dielectric properties of the Barium- and Ceriumsubstituted LaFeO3 compound. The X-ray diffraction analysis revealed that both compounds crystallized in the orthorhombic structure belonging to the Pnma space group. The rise of the annealing temperature from 700 to 900 °C was found to lead to the increase of the average grain size value as characterized by SEM. Furthermore, two clear relaxations phenomena have been detected using the Nyquist and Argand’s plots of dielectric impedance and Modulus curves at different temperatures, which are attributed to both grain and grain boundary contributions. Their activation energies have been calculated not only from the frequency dependence of both imaginary parts of impedance (Z00 ) and modulus (M00 ) but also from the contribution of the resistances deduced from the Nyquist plots. These plots have been adjusted using two circuits in series, each of which containing a resistance in parallel to a CEP capacitance. The conduction mechanism was analyzed by ac conduction using the Jonscher’s power law. The NSPT conduction model has been confirmed for both compounds in which the rise in heat treatment decreases the binding energy of carriers.
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Springer Science+Business
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https://doi.org/10.1007/s10854-020-04140-w
J Mater Sci: Mater Electron
1 Introduction The perovskite oxides with ABO3 structure, in which the A-site cation is a rare-earth element and the B-site is a transition metal (Cr, Mn, Fe, Co, etc.), have been the most studied oxides as potential candidates for various applications over the past few years [1–5]. These perovskites, with ‘La’ in position A and ‘Fe’ in B position, are called the lanthanum orthoferrites ‘‘LaFeO3’’ (LFO3), which present an orthorhombically distorted perovskite structure (Pnma space group). These lanthanum orthoferrites are known as an antiferromagnetic (AFM) metals with a high ordering temperature TN * 740 K [6]. Think to their different physical properties, they are used for a long time ago in many applications: magnetic materials [7], a novel sensing material for detecting tox
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