Enhancement of Thermoelectric Performance of Sr_0.9Ba_0.1Ti_0.8Nb_0.2O₃ Ceramics by A-Site Cation Nonstoichiometry

Sr_0.9Ba_0.1?xTi_0.8Nb_0.2O₃ ceramics (x=0, 0.01, 0.02 and 0.05) are prepared by solid state reaction, whose thermoelectric properties are investigated from 323 K to 1073 K. By introducing A-site nonstoichiometry, the absolute Seebeck coefficient is enhanced, while the electrical resistivity is surprisingly reduced due to the significantly enhanced carrier mobility. These results are dramatic in thermoelectric materials, effectively enhancing the power factor. Moreover, the thermal conductivity is reduced, thus the thermoelectric performance of Sr_0.9Ba_0.1Ti_0.8Nb_0.2O₃ ceramic is significantly enhanced by A-site nonstoichiometry.