Structural, Microstructural, Dielectric and Ac-conductivity of CaTi1-xFexO3 Multiferroic Materials Synthesized by Solid State Method

Abstract

In this study, the structural, microstructural, dielectric and conductivity properties of Fe-doped CaTiO3 (CT) ceramic were investigated. These ceramics were successfully synthesized using the conventional solid-state method. The X-ray diffraction and Rietveld refinement results showed that the ceramics at x=0.0, 0.1, 0.2 and 0.3 crystalized in the orthorhombic phase with the Pmmm space group. While for x=0.4, 0.5 and 0.6, the phase formation changes from orthorhombic to tetragonal phase with P4/mmm group space. The SEM results revealed a semi-spherical shape of grain for lower Fe content (≤0.4), while at x=0.5 and 0.6 an agglomeration phenomenon is observed and the observed density of the sample at x=0.5 is higher than the other ceramics. The dielectric properties were studied as function of frequency and temperature. The dielectric permittivity (ɛ’r) decreases as function of frequency at lower frequency region and remain almost independent of frequency at high frequency region in the whole temperature range of R.T–520 °C. Each converges at high frequency (>105 Hz) for all the temperatures. The evolution of ɛ’r as function of temperature for pure CT ceramic showed a stability at large range of temperature (from R.T to 250°C). For substituted ceramics, we obtained a phase transition which shifted to the lower temperature with the increase of Fe content. And the value of ɛ’r, increases for Fe-doped CT ceramics and reaches a maximal value for x=0.5 which is 50 time bigger than the pure ceramic. The AC conductivity, σAC, is found to increase rapidly as a function of frequency, at low frequency region, and increases linearly at high frequency region, which confirms the hopping of electrons related to the conduction mechanism. The σAC evolution is found to follow the Jonscher’s law and the s exponent decreased with the increasing temperature which is related to the correlated barrier height (CBH) model. And the σAC values increase with the increases of Fe content.