Eur. Phys. J. Plus (2021) 136: 186
https://doi.org/10.1140/epjp/s13360-021-01134-3

Regular Article

Assessment of nanostructure, optical, dielectric and modulus response by Bi substitution in La_1−x Bi _x Ni_0.5Ti_0.5O₃ (x = 0.0–0.2) system

¹ Laboratoire de Physique Appliquée, Faculté des Sciences, Université de Sfax, 3000, Sfax, Tunisia
² CEMMPRE, Mechanical Engineering Department, University of Coimbra, 3030-788, Coimbra, Portugal
³ CFisUC, Physics Department, University of Coimbra, 3004-516, Coimbra, Portugal
⁴ MOLTECH-Anjou, Laboratoire de Photonique, Université d’Angers, 2 Bd. Lavoisier, 49045, Angers, France
⁵ Laboratoire des Matériaux Céramiques et Procédés Associés, Université de Valenciennes et du Hainaut-Cambrésis, Maubeuge, France
⁶ Université de Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000, Grenoble, France

^a azzouzi.sirine@outlook.com

Received: 4 December 2020
Accepted: 17 January 2021
Published online: 6 February 2021

Abstract

Perovskite-type oxides La_1-x Bi _x Ni_0.5Ti_0.5O₃ (x = 0.0, 0.2) were prepared by the sol–gel method employing the citric acid route and sintered at 820° C. The structural behavior analyzed by X-ray diffraction proved that all the samples have the same crystallographic structure (space group Pnma). The volume of the elemental lattice decreases with the rate of Bismuth substitution. Transmission electron microscopy (TEM) verified the nanosized grains. The FTIR spectra confirmed the formation of the orthorhombic perovskite structure. UV–Visible spectroscopy and photoluminescence were also applied to study the samples. The parameters of real and imaginary part of dielectric function (ε′ and ε″) and dielectric loss tangent (tg(δ)) show a strong frequency dependence. Those dependences explain a dispersive behavior at low frequencies and are outlined on the basis of the Maxwell–Wagner model and Koop theory. The compounds have very high dielectric constant values (ε′ ≈ 10³) that are useful in electronic devices. Electric modulus formalism was employed to investigate the relaxation dynamics of charge carriers. Moreover, a non-Debye type of relaxation was verified in our samples. The activation energy is specified from the analysis of the imaginary part of the electric modulus.