Effect of mono-dopants (Mg2+) and co-dopants (Mg2+, Zr4+) on the dielectric, ferroelectric and optical properties of BaTiO3ceramics

Abstract

In this work, BaTiO3, Ba(Mg0.01Ti0.99)O3, Ba(Mg0.015Ti0.985)O3, Ba(Mg0.02Ti0.98)O3 and Ba(Mg0.01Zr0.15Ti0.84)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 x Ti1-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(Mg0.01Zr0.15Ti0.84)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 x Ti1-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(Mg0.01Zr0.15Ti0.84)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 x Ti1-x)O3 ceramics, a significant reduction of Ti-O bond strength was observed. However, BaTiO3, Ba(Mg0.01Ti0.99)O3, Ba(Mg0.015Ti0.985)O3 and Ba(Mg0.02Ti0.98)O3 ceramics had manifested P-E loop having lower remanent polarization and coercive field compared to Ba(Mg0.01Zr0.15Ti0.84)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.