Impedance spectroscopy and dielectric properties of Ce and La substituted Pb0.7Sr0.3(Fe0.012Ti0.988)O3 nanoparticles

We present the structural, microstructural, dielectric and impedance behavior of Pb_0.7Sr_0.3(Fe_2/3Ce_1/3)_0.012Ti_0.988]O₃ (PSFCT) and Pb_0.7Sr_0.3(Fe_2/3La_1/3)_0.012Ti_0.988]O₃ (PSFLT) nanoparticles. These nanoparticles were prepared by a chemical synthesis route using polyvinyl alcohol as surfactant. The X-ray diffraction pattern shows polycrystalline nature with coexistence of tetragonal and cubic phase in both PSFCT and PSFLT nanoparticles. The average particle size has been measured using Scherer's relation. The average particle sizes also measured by TEM are 10 and 11 nm, and by SEM 9 and 12 nm, respectively, of PSFCT and PSFLT nanoparticles. By measuring the value of relative permittivity (?′) and loss (tan δ) at lower frequency, the dielectric properties show Maxwell-Wagner type interfacial polarization. However, due to nano size effect of PSFCT and PSFLT, dispersionless dielectric response has been observed up to higher frequency of 15 MHz. The frequency dependent real (Z′) and imaginary (Z″) parts of impedance confirmed the variation which was observed in dielectric properties. The values of resistance of grain boundaries, R_gb is higher than grains, R_g indicates that the effect of grain boundaries is dominant on electrical properties when the size of nanoparticles is quite small.