Effect of cobalt doping on the crystal structure, magnetic, dielectric, electrical and optical properties of PbTi1−xCoxO3-δ perovskite materials

Abstract

In this work, experimental investigation of structural, morphological, magnetic, dielectric, electrical, and optical properties of cobalt-doped PbTi1−xCoxO3-δ perovskite materials (0 ≤ x ≤ 0.4), synthesized by the solid-state reaction method, was reported. X-ray diffraction measurements revealed the tetragonal perovskite structure with the P4mm space group for all the samples. The SEM images showed a decrease in the average grain size from 1.23 to 0.11 µm as cobalt dopant amount increases. The magnetic hysteresis loops sufficiently indicated the antiferromagnetic character for all the synthesized samples. At room temperature, the dielectric constant exhibited a decrease with the increasing Co amount. However, both the dielectric constant and dielectric loss increased with temperature without the appearance of any phase transition from room temperature to 380 °C. The σac plots versus frequency showed an increase, according to the Jonscher power law. Complex impedance results demonstrated the semiconducting nature for all the ceramics through the presence of the negative temperature coefficient of resistivity. For all samples, the transport properties of charge carriers were found to be thermally activated. Thermal evolution of the σdc for all the compounds was described by the Arrhenius law. The transport mechanism was found governed by the electrons resulting from the ionization of the oxygen vacancies. The optical results of all compounds showed strong absorption in the whole visible range. The optical band gap energy was found in the semiconducting range 2.98–1.12 eV.