Conduction mechanisms and thermoelectric applications of La_1-xSr_xCoO₃ nanofibers

Single-phase La_1-xSr_xCoO₃ (x = 0, 0.01, 0.03, 0.05, 0.07, and 0.1) nanofibers were synthesized via electrospinning technique. Different characterization techniques were employed to characterize the electrospun nanofibers. SEM was used to observe the morphology and size of the electrospun nanofibers, and the diameter of all fabricated nanofibers was found in the nanometer (nm) range. The XRD patterns of all the samples after heat treatment at 600 °C confirm the single-phase formation of La_1-xSr_xCoO₃ (x = 0, 0.01, 0.03, 0.05, 0.07, and 0.1) nanofibers. The single phase of all the samples was also confirmed by FTIR spectroscopy and had good agreement with XRD results. All the fabricated samples’ thermal behavior was studied using TG/DTA, and all samples showed thermal stability at ≤ 600 °C. The single-phase La_1-xSr_xCoO₃ (x = 0, 0.01, 0.03, 0.05, 0.07, and 0.1) nanofibers-based devices were fabricated on inter-digitated electrodes, and IV characteristics curves of all the fabricated devices show that La_1-xSr_xCoO₃ (x = 0, 0.01, 0.03, 0.05, 0.07, and 0.1) nanofibers exhibit semiconductor-like behavior. The electrical conductivity of all the samples was calculated and found to decrease with increasing concentration of Sr doping. In all samples, the dominant conduction mechanism is ohmic at low voltage, while space-charge-limited current is the dominant conduction mechanism at high voltage and low temperature. The Seebeck coefficient of all the fabricated devices was calculated and found to increase with increasing Sr concentration and temperature.