Effect of Ca-additions on structural and electrical properties of Pb(SnTi)O3 nano-ceramics

Polycrystalline samples of Ca-modified Pb(SnTi)O3 (i.e., Pb1−xCaxSn0.15Ti0.85O3, x = 0, 0.03, 0.06 and 0.09) were prepared by the precursor solution method. X-ray diffraction (XRD) of the compounds suggests that they exhibit single phase with tetragonal crystal structure. SEM micrograph of the materials shows uniform grain distribution on the surface of the samples. TEM micrographs of the above compounds reveal that their particle size is less than 30 nm. Detailed dielectric studies of the compounds at different temperature suggest that with increasing Ca concentration in the compound, the value of the dielectric constant first increases for (x = 0, 0.03 and 0.06) and then decreases for (x = 0.09). The compounds do not exhibit any ferroelectric relaxor behavior, i.e., they exhibit diffuse phase transition and frequency dependent high permittivity. Some impedance and electrical properties of the materials were studied using an impedance spectroscopic technique (CIS) in a wide range of temperature (30-500 °C). The Nyquist plot clearly shows the presence of both bulk and grain boundary effects in all the compounds.