Abstract
In the present study, calcium cobalt oxide-based ceramic oxide (Ca3Co4O9 +/-delta) is synthesized by various reducing agent method by metal complex-assisted sol-gel assisted followed by combustion method using various reducing agents. The reducing agents adopted in the study are citric acid, starch polymer, and polyethylene glycol. The detailed structural and surface characterizations of as-prepared Ca3Co4O9+delta have demonstrated by XRD, TGA, and diffuse UV-visible spectral analysis. Hydrothermal method-prepared Iron-doped Ca3Co4O9 +/- delta ceramic shows the Nanorods' morphology. Electrical properties such as conductivity, Hall co-efficient, and electron mobility studies have been demonstrated. The density of the prepared materials by changing the stoichiometry ranges from 2.72 g/cm(3) (relative density 55%) to 2.91 g/cm(3) (relative density 58.9%). The density is found to be improved by decreasing the amount of calcium. The higher density is obtained for Ca-2.90 Co3.91O9 +/-delta which is 2.91 g/cm(3) (58.9% of theoretical density). The effect of foreign metal ion doping in bulk calcium carbonate has studied and compared their electronic properties. The various reducing agent method-prepared Ca3Co4O9 +/-delta shows the promising thermoelectric features. Polymer method-prepared Ca3Co4O9 +/-delta sample with various transition metal ion substitution shows (calcium-doped ceramic oxide) the higher electron mobility and conducting activity.