Complex impedance analysis of layered perovskite structure electroceramics—NaDyTiO4

A ceramic oxide (NaDyTiO4), having layered perovskite structure, has been prepared by a standard high-temperature solid-state reaction technique. X-ray diffraction (XRD) studies have confirmed material formation under reported condition along with the presence of impurity (Na2Dy2Ti3O10) as the minor phase. Complex impedance spectroscopy (CIS) analysis has been carried out to investigate its microstructure and electrical properties as a function of frequency and temperature. CIS analysis has indicated that the electrical behavior of the material sample shows negative temperature coefficient of resistance (NTCR) typical to a semiconductor. Impedance studies have also indicated the presence of temperature dependent relaxation process in the material with a spread of relaxation time. The d.c. conductivity of the material as evaluated from the impedance spectrum has been observed to be ∼10−9 Scm−1 at room temperature (RT). It has been observed to increase as a function of temperature with a maximum of ∼10−5 Scm−1 at 550◦C. The conductivity variation shows a cross over from Mott-type hopping phenomena at lower temperatures to a thermally activated Arrhenius type behavior at high temperature. C 2005 Springer Science + Business Media, Inc