Structural and thermoelectric properties of Ag doped (Ca2Co2O5)

Phase controlled silver doped calcium cobalt oxide Ca₂Co_2-xAg_xO₅, x = (0,0.04,0.08,0.12), was synthesized in the present work by the sol-gel method. X-ray diffraction (XRD) confirmed the synthesis of pure Ca₂Co₂O₅ and the doping of silver in orthorhombic calcium cobalt oxide. Theoretical modeling of XRD verified the doping, with both experimental and theoretical results indicating peak shifting toward lower angle. To check the morphology and nano-scale porosity of the sintered samples, scanning electron microscopy (SEM) was employed. Silver doping significantly increased electrical conductivity due to an increase in carrier concentration, which was optimum at x = 0.12. Alongside this, composition exhibited a notable reduction in thermal conductivity due to defects in the crystal structure. Moreover, the Seebeck coefficient was slightly decreased due to an increase in the charge carrier. As a result, in the current study, the thermoelectric figure of merit (zT) demonstrated a notable enhancement of 29 % as compared to pure Ca₂Co₂O₅ at 820 K.