Facile synthesis of samarium and cerium doped double perovskite cobaltite with enhanced dielectric response

Abstract

The investigation of Sm–Ce doping on structure, conduction, and dielectric response of Bi2Ca2–2xSmxCexCoO6 (x = 0.000, 0.025, 0.050, 0.075) (BCSCCO) are presented. All the specimens were synthesized by a facile synthesis technique named the co-precipitation route. X-ray diffraction (XRD) reveals that BCSCCO crystallizes into one phase with space group P21/m. The crystallite size, dislocation density, lattice parameters, lattice strain, unit cell volume, and bulk density were determined using XRD data. The structural properties of Bi2Ca2CoO6 were examined using calculations based on the density functional theory. Theoretical and experimental values discrepancy is less than 1%. A scanning electron microscope was used for performing a microstructural analysis. The SEM images demonstrate the homogeneous distribution of grains with a range of sizes (0.054–0.090 μm). The alternating current (ac) conductivity, dielectric permittivity, and tangent loss were also studied as a function of frequency (20 Hz–3 MHz) at different temperatures (100–500 °C). All synthesized samples were examined using non-linear Debye's function to determine their spreading factor and relaxation time. The specimen with the lowest crystallite size (∼23 nm) exhibits a high dielectric permittivity (∼3.80 × 106). The conduction mechanism was examined in the studied samples with the use of Jonscher's power law. The power law indicates that the BCSCCO (x = 0.000, 0.025) follows correlated barrier hopping, whereas the x = 0.050 and 0.075 compositions follow non-overlapping polaron tunneling. The studied specimen Bi2Ca1.90Sm0.050Ce0.050CoO6 with the highest density (∼5.65 g/cm3) displays a high electrical conductivity (∼46.1 S/cm). These findings correspond to those published for ceramics made from calcium cobaltite using solid–state reactions (5.0–26.0 S/cm).