Phase formation, microstructure, electrical and magnetic properties of Mn substituted barium titanate

Mn doped barium titanate (BaTi1−xMnxO3) ceramics with x=0, 1, 2.5, 5, 7.5 and 10% have been synthesized by a solid state reaction method. X-Ray Diffraction (XRD) patterns reveal that, the phase transition from tetragonal to hexagonal takes place at x=1% concentration and complete hexagonal phase is obtained for x≥5%. It is found that, the lattice parameters of the samples have been increased with Mn concentration. As the Mn concentration increases, the grain size increases and the grains develop hexagonal and rectangular morphology. The remnant polarization (Pr) for pure barium titanate (BTO) is 7.50 µC/cm2 and further decreases with increase in Mn concentrations. All the samples exhibit ferromagnetism at room temperature. The magnetization at a magnetic field of 5 kOe is depended on Mn concentration. It gradually increases, and reaches a maximum value of ~0.013 emu/g for x=10%. The origin of ferromagnetism in the samples is due to exchange interaction between the different oxidation states of Mn. The dielectric constant and dielectric loss also decreases as Mn content increases.