Effect of mono-dopants (Mg²⁺) and co-dopants (Mg²⁺, Zr⁴⁺) on the dielectric, ferroelectric and optical properties of BaTiO₃ ceramics

In this work, BaTiO₃, Ba(Mg_0.01Ti_0.99)O₃, Ba(Mg_0.015Ti_0.985)O₃, Ba(Mg_0.02Ti_0.98)O₃ and Ba(Mg_0.01Zr_0.15Ti_0.84)O₃ ceramics have been prepared through conventional solid-state route to investigate the effects of Mg²⁺ and Zr⁴⁺ dopants as mono-substitution (only Mg²⁺) and co-substitution (Mg²⁺ and Zr⁴⁺) of B-site on the structural, electrical and optical properties of BaTiO₃ ceramics. Exhibiting perovskite structure, Ba(Mg_xTi_1−x)O₃ ceramics revealed a decrement pattern of tetragonality with the increment of the concentration of MgO which was confirmed through Rietveld analysis. Morphological analysis of the sintered samples by scanning electron microscope showed a grain growth retardation phenomenon with Mg²⁺ addition. Releasing from this retardation process, Ba(Mg_0.01Zr_0.15Ti_0.84)O₃ showed a maximum dielectric constant of ∼1269.94 due to the enhanced domain wall motion and the confinement within the solubility limit of Mg²⁺. The ferroelectric characteristic of Ba(Mg_xTi_1−x)O₃ was sluggish due to the effects of grain size and its boundary. The optical band gap for BaTiO₃ was found to be decreased from 3.55 eV to 3.06 eV with the addition Mg²⁺ content but for Ba(Mg_0.01Zr_0.15Ti_0.84)O₃, the value increased due to the Burstein-Moss effect. Again the FTIR analysis proved that no impurity phases were formed during the doping phenomenon, but in Ba(Mg_xTi_1-x)O₃ ceramics, a significant reduction of Ti-O bond strength was observed. However, BaTiO₃, Ba(Mg_0.01Ti_0.99)O₃, Ba(Mg_0.015Ti_0.985)O₃ and Ba(Mg_0.02Ti_0.98)O₃ ceramics had manifested P-E loop having lower remanent polarization and coercive field compared to Ba(Mg_0.01Zr_0.15Ti_0.84)O₃ ceramics with moderate electrical and optical properties. So, co-doping with Mg²⁺ and Zr⁴⁺ evidenced a favorable accession for the increment of the properties of BaTiO₃ ceramics. (paper)