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Effect of synthesis route on structural, morphological, Raman, dielectric, and electric properties of La0.8Ba0.1Bi0.1FeO3

Authors: Benali, EM; Benali, A; Bejar, M; Dhahri, E; Graca, MPF; Valente, MA; Costa, BFO

Ref.: J. Mater. Sci.: Mater. Electron. 31(4), 3197-3214 (2020)

Abstract: Two compounds with the formula La0.8Ba0.1Bi0.1FeO3 have been prepared by the sol–gel (LBBFO-SG) and the auto-combustion (LBBFO-AC) preparation methods. The effect of the preparation method on structural, morphology, vibrational, electrical, and dielectric properties have been carried out using the X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Raman and impedance spectroscopy. The Rietveld refinement of the XRD diffractograms confirms the crystallization of both compounds through the Pnma space group. Furthermore, the nano-size scale of the prepared compounds was verified by the XRD and the SEM microscopy. From the Raman study, we conclude that the vibration modes are similar to those of the pure LaFeO3 with a slight shape change in some modes. The relaxation processes were analyzed with the Bergmann formalism to validate the presence of two relaxation processes corresponding to grains and boundary grains contributions. These relaxations have been confirmed by studying the dielectric constant also the dielectric loss tangent is used to study the ferroelectric–paraelectric phase transition at around room temperature. The activation energy for both contributions has been calculated from the impedance, the modulus, and the dielectric loss tangent and they have almost the same values. The Nyquist plots (Z″ vs. Z′) have been adjusted using two circuits in series containing each one a resistance in parallel to a CEP capacitance.

DOI: 10.1007/s10854-020-02867-0