Article ID Journal Published Year Pages File Type
10629414 Journal of the European Ceramic Society 2016 7 Pages PDF
Abstract
The effect of Bi doping on the nanostructure and thermoelectric performance of the polycrystalline calcium cobaltite Ca3−xBixCo4O9 (x = 0, 0.1, 0.2, 0.3 and 0.4) is reported. The samples were prepared using a chemical sol-gel route. Increasing Bi concentrations up to x = 0.3 enhance the grain growth and improve the crystal texture. Through nanostructural and chemical analyses, significant Bi segregation at grain boundary was observed for the first time. From 318 K up to 1073 K, the Seebeck coefficient increases and the electrical resistivity decreases as Bi increases to 0.3, resulting in high power factor of 0.95 mW m−1 K−2 at 318 K, which is so far the highest power factor for Calcium Cobaltite ceramics. Combined with low thermal conductivity of 1.9 W m−1 K−1, Ca2.8Bi0.2Co4O9 shows the peak ZT value of 0.43 at 1073 K. The Bi grain boundary segregation improves the texture development and acts as carrier filter in increasing the Seebeck coefficient.
Related Topics
Physical Sciences and Engineering Materials Science Ceramics and Composites
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