Three low-dimension cobaltites in the Sr-Ca-Co-O system have been studied for their structure and thermoelectric properties. Using x-ray pole figure construction technique, a Ca3Co4O9 thin film showed excellent fiber texture but no ab in-plane texture. The fiber texture is mainly responsible for the excellent thermoelectric properties. Our study of a high-throughput combinatorial thin film (synthesized using Pulsed Laser Deposition) with a custom-built power factor screening tool demonstrated that the La substitution in the Ca-site of Ca3Co4O9 increases Seebeck coefficient and resistivity due to decrease of hole concentration. The Sr-substitution on the Ca-site increases the carrier mobility, therefore lower resistivity of the film. The homologous compounds Can+2ConCo O3n+3 and Srn+2ConCo O3n+3 consist of parallel 1-dimensional (Co2O6)6- chains that are built by successive alternating face-sharing CoO6 trigonal prism and n units of CoO6 octahedra along the c-axis. However, due to the high resistivity of these compounds, they will unlikely yield ZT values comparable to that of Ca3Co4O9.
Proceedings Title: International Symposium on Advanced Dielectric Materials and Electronic Devices
Conference Dates: October 5-10, 2008
Conference Location: Pittsburgh, PA
Conference Title: Materials Science and Technology 2008 Conference and Exhibit (MS&T08)
Pub Type: Conferences
thermoelectric, Ca3Co4O9, Can+2ConCo O3n+3, Srn+2ConCo O3n+3