Improvement of Bi2Sr2Co2Ox thermoelectric performances by K doping

Resumen del póster presentado a la 14th European Conference on Thermoelectrics, celebrada en Lisboa (Portugal) del 20 al 30 de septiembre de 2016.
Bi2Sr2-xKxCo2Ox polycristalline ceramics with x=0.0, 0.025, 0.050, 0.075, 0.10, 0.125, and 0.15 have been prepared using the classical solid state technique. SEM micrographs have shown that all the K has been incorporated into the Bi2Sr2Co2Ox structure. It has been found that K drastically raises grain sizes. Electrical resistivity has been clearly modified by K doping, from a semiconducting-like behavior (dρ/dT0) for all the K substituted samples. Moreover, K significantly decreases the resistivity values until 0.0125K, slightly increasing for higher content. On the other hand, Seebeck coefficient also decreases with K substitution. Power Factor increases with K content until 0.075, decreasing for further K addition. These results indicate that small K-substitution can be very useful in order to strongly reduce electrical resistivity and, in spite of a Seebeck coefficient decrease, raising the thermoelectric performances of these ceramic materials.
This work is partially supported by Research Fund of Hakkari University, Hakkari, Turkey, under grant contracts no: MF2016AYP