Influence of Addition of Alumina Nanoparticles on Thermoelectric Properties of La-Filled Skutterudite CoSb3 Compounds

The CoSb3-based compound is a promising thermoelectric material useful in the temperature range of 600-900 K. It, however, has a higher thermal conductivity. Thus, reducing the thermal conductivity causes improvement of the thermoelectric performance. In this work, we tried to reduce the thermal conductivity by both filling La and dispersing alumina nanoparticles (ANPs) into the compound. The raw powders of LaSb, Co, Ni, Sb and Te were prepared. The n-type La-filled compound was synthesized from the raw powders using a planetary ball mill. Then, ANPs were added to the combined powder and further mixed using the planetary ball milling. The mixture was sintered by a pulse-discharge sintering method. The combining phases of the samples were characterized by X-ray diffraction analysis. The thermoelectric properties were measured for the samples. Influence of addition of ANPs on the properties was studied. Adding 0.05 mass% ANPs reduced the thermal conductivity. The sample added 0.5 mass% or more ANPs increased both the electrical resistivity and the thermal conductivity. As a result, the sample added 0.05 mass% ANPs had the maximum performance of ZT = 1.15 at 873 K. [doi:10.2320/matertrans.E-M2012821]