Abstract
Polycrystalline perovskite nanomaterials (Pb0.88La0.12)(FexTi1-x)0.97O3 were prepared by sol-gel reaction method. The crystal structure examined by X-ray powder diffraction indicates that the material was single phase with pseudocubic structure. EDX and SEM studies were carried out in order to evaluate the quality and purity of the compounds. The crystal symmetry, space group, and unit cell dimensions were determined from Cell-Ref software, whereas crystallite size was estimated from Scherrer’s formula. A correlation between grain size and diffuse character for the samples has been observed. Dielectric studies exhibit a diffuse phase transition characterized by a strong temperature and frequency dispersion of the permittivity and a relaxor behaviour. We have observed that dielectric constant decreases and ac conductivity increases with the frequency. The dielectric relaxation has been modeled using the Curie-Weiss and modified Curie-Weiss laws. The calculated activation energy Ea for x=1% and 3% was between 0.91–2.1 eV and 0.425–1.08 eV, respectively. The relaxation times were estimated from the Arrhenius law.
Highlights
Perovskite-structured ferroelectric crystals have the general formula ABO3, where A is mono- or divalent ion with large radius and low valence, while B is a tetra- or pentavalent ion with small radius and high valence [1]
All the peaks of the XRD patterns of the PLFT ceramics were indexed and the lattice parameters were determined in various crystal systems, using a computer program (Cell-Ref)
La3+ and Fe3+ modified PbTiO3 (PLFT) compounds were prepared by sol-gel process using the colloidal destabilization method (DSC) followed by some heat treatments
Summary
Perovskite-structured ferroelectric crystals have the general formula ABO3, where A is mono- or divalent ion with large radius and low valence, while B is a tetra- or pentavalent ion with small radius and high valence [1]. Sol-gel process has been used to synthesize nanocrystalline ferroelectrics This method offers several advantages (such as gaining time, saving energy, and better homogeneity) more than the other conventional methods. Complex impedance spectroscopy (CIS) is a well-known technique to investigate electrical properties of materials. It describes the electrical processes occurring in a system on application of an AC signal as input perturbation [10]. It is a useful technique with enormous potential and possibilities for investigation and for characterization of the electrical and electrochemical properties of electroceramics materials. A much more profound analysis is possible by combining the impedance analysis with use of the complex electrical formalism [12]
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