Complex impedance analysis of layered perovskite structure electroceramics-NaDyTiO4

NaDyTiO4, having layered perovskite structure, was prepared by a standard high-temperature solid-state reaction technique. XRD studies confirmed material formation under reported conditions along with the presence of impurity (Na2Dy2Ti3O10) as the minor phase. Complex impedance spectroscopy (CIS) analysis was carried out to investigate its microstructure and electrical properties as a function of frequency and temperature. CIS analysis indicated that the electrical behaviour of the material sample showed negative temperature coefficient of resistance (NTCR) typical of a semiconductor. Impedance studies also indicated the presence of temperature dependent relaxation process in the material with a spread of relaxation time. The dc conductivity was about 10 exp(-9) S/cm at room temperature. It increased as a function of temperature with a maximum of about 10 exp(-5) S/cm at 550 C. The conductivity variation shows a cross-over from Mott-type hopping phenomena at lower temperatures to a thermally activated Arrhenius type behaviour at high temperatures.