Synthesis, Microstructure, and Dielectric Properties of Mn-Doped 0.33BaTiO₃-0.67BiFeO₃ Multiferroic Solid Solutions

In this work, 0.33BaTiO3-0.67BiFeO3 multiferroic ceramics doped with x mol% MnO2 (x= 0.1-1.0) were fabricated by solid-state reaction method, and their microstructure and dielectric property were also investigated. The perovskite phase structure of the solid solutions was confirmed by X-ray diffraction patterns, and the formation of minor impure phase of Bi2Fe4O9 was prevent effectively by Mn-doping. With increasing the Mn-doped concentration, the dielectric constants of Mn-doped 0.33BaTiO3-0.67BiFeO3 multiferroic ceramics first increased, and reached a maximum value of 340 (measured @1MHz) at the Mn-doped concentration of 0.60 mol%, and then decreased. On the other hand, the dielectric losses first decreased, and reached the minimum value at the Mn-doped concentration of 0.30 mol%, and then increased along with increasing the Mn-doped concentrations. The ferroelectric domain structures in the Mn-doped 0.33BaTiO3 - 0.67BiFeO3 multiferroic ceramics with rhombohedral symmetry were also revealed by TEM image and selected area electron diffraction patterns, and tweed-like domain structures were observed.