Improving of Thermoelectric Efficiency of Layered Sodium Cobaltite Through its Doping by Different Metal Oxides

Through the solid-state reactions method the Na0.89Co0.9Me0.1O2 (Me = Cr, Ni, Mo, W, Pb, Bi) ceramic samples were prepared and their crystal structure, microstructure, electrical, thermal and thermoelectric properties were investigated. The effect of nature of doping metal (Me = Cr, Ni, Mo, W, Bi) on the structure and properties of layered sodium cobaltite Na0.89CoO2 was analyzed. The largest Seebeck coefficient (616 (μV/K) at 1073 K ) and figure-of-merit (1.74 at 1073 K) values among the samples studied demonstrated the Na0.89Co0.9Bi0.1O2 solid solution, which also characterized by lowest value of dimensionless relative self-compatibility factor about 8% within 673–873 K temperature range. The obtained results demonstrate that doping of layered sodium cobaltite by transition and heavy metal oxides improves its microstructure and thermoelectric properties, which showes the prospectiveness of used doping strategy for development of new thermoelectric oxides with improved thermoelectric characteristics.