Enhanced thermoelectric properties of single phase Na doped NaXCoO2 thermoelectric material

Single-phase thermoelectric materials Sodium (Na) doped Cobalt Oxide NaxCoO2 (x = 1, 0.98, 0.96 and 0.94) were synthesized by the sol-gel method. Structural and morphological analysis of the prepared samples revealed excellent phase purity and high crystallinity. We found out that the direct current (DC) electrical conductivity was enhanced with the decrease in Na content, whereas, the thermal conductivity of the prepared samples increased slightly by decreasing the Na concentration. Seebeck coefficient was also increased and consequently, a figure of merit (zT) value of 1.24 was obtained at 1010 K which is about 28% improvement compared to the undoped sample.