Toshio Kono

Thermoelectric properties of delafossite-type layered oxides AgIn1−xSnxO2

The thermoelectric properties of delafossite-type layered oxides AgIn1−xSnxO2 that consist of alternating layers of Ag and In1−xSnxO2 were investigated to elucidate their potential as a thermoelectric material. Polycrystalline materials of the AgIn1−xSnxO2 were prepared by a cation exchange reaction between NaIn1−xSnxO2 and AgCl. The solubility limit of the Sn atoms on the In sites was approximately x=0.05. The electrical conductivity and Seebeck coefficient were measured between 373 and 673K in air. Undoped AgInO2 was an n-type semiconductor with conductivities of 10−4–10−2Ω−1cm−1, and the electron carriers were generated via the formation of oxygen vacancies. AgIn0.95Sn0.05O2 was an n-type degenerate semiconductor with conductivities of 100–101Ω−1cm−1 where the Sn atoms acted as electron donors. This drastic increase in the electrical conductivity increased the thermoelectric power factor by approximately two orders of magnitude to 10−6–10−5Wm−1K−2.