Structural, dielectric and electrical behavior of Bi0.85Tm0.15FeO3 ceramic

Abstract

The (Bi0.85Tm0.15)FeO3 (BTFO) and BiFeO3 (BFO) ceramic compounds have been prepared by using a standard ceramic technology (i.e., high-temperature solid-state reaction route). The formation of the above compounds was checked by the detailed analysis of X-ray diffraction (XRD) data using standard computer programming software ‘POWD’. All the diffraction peaks of the XRD patterns of the above compounds were indexed through JCPDS files of X'Pert High Score plus. These compounds (BFO and BTFO) were found to crystallize in rhombohedral symmetry with few impurity phases present in the structure. A dielectric peak observed in a temperature range of 250C–350 °C is due to the magnetic phase transition occurring in the materials (BFO and BTFO). The calculated value of tolerance factor reveals the degree of distortion occurring in the ideal perovskite structure. Impedance study indicates the presence of both NTCR (negative temperature coefficient of resistivity) and PTCR (positive temperature coefficient of resistivity) behavior in a different temperature range. The role of grain and grain boundary effects in the electrical properties was discussed with the respective fitting parameters (Rg, Rgb, CPE etc.) of the materials. Activation energy has been calculated at different temperature through Nyquist plot, and also from the slopes of Arrhenius (σac∼1/T) plot. The polarization versus electric field (PE) hysteresis loops of BFO and BTFO gave the evidence of ferroelectric behavior present in the compounds.