Investigation of high-temperature transport mechanism and dielectric properties of RE-double-doped perovskite cobaltite using co-precipitation technique

Abstract

In the present work, the co-precipitation method was used to prepare a Bi2Ca1.80Sm0.10La0.10CoO6+δ (BCSLCO). The structure was investigated using X-ray diffraction (XRD) which confirms the monoclinic structure having space group P21/m. The specimen crystallite size, unit cell volume, lattice strain, dislocation density, bulk density, and lattice parameters were determined using XRD data. To determine the crystallite size, the Scherer formula was utilized. FT-IR spectrum in the frequency range 400–1000 cm−1 shows four absorption bands in the fingerprint region. The morphology was examined using energy-dispersive X-ray (EDX) and scanning electron microscopy (SEM). To study the thermal stability of the studied sample thermogravimetric analysis (TGA) has been employed. The dielectric constant, AC conductivity, and tangent loss were investigated at various temperatures using a frequency range of 20 Hz to 3 MHz. The high value of dielectric constant is 1.06 × 106 at 500 °C. In the temperature ranges of 100–500 °C, dielectric parameters were used to measure ac electrical conductivity. AC conductivity σac of the synthesized sample is studied at (100–500 °C) using Jonscher's universal power law σac = σdc + Aωn. In this work, the foremost objective is to examine the conduction mechanism of double doped RE in BCCO. Impedance analysis using Nyquist plots reveals that grain contribution increases as temperature rises, whereas grain boundary contribution decreases.