Effect of rare earth doping on impedance, modulus and conductivity properties of multiferroic composites: 0.5(BiLaxFe1-xO3)-0.5(PbTiO3)

Abstract

The Lanthanum-doped bismuth ferrite-lead titanate compositions of 0.5(BiLaxFe1-xO3)-0.5(PbTiO3) (x = 0.05, 0.10, 0.15, 0.20) (BLxF1-x-PT) were prepared by mixed oxide method. Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature. The lattice parameter c/a ratio decreases with increasing of La(x = 0.05-0.20) concentration of the composites. The effect of charge carrier/ion hopping mechanism, conductivity, relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range (102-106 Hz) at different temperatures. The nature of Nyquist plot confirms the presence of bulk effects only, and non-Debye type of relaxation processes occurs in the composites. The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials. The ac conductivity and dc conductivity of the materials were studied, and the activation energy found to be 0.81, 0.77, 0.76 and 0.74 eV for all compositions of x = 0.05-0.20 at different temperatures (200-300°C).