Investigation on the assessment of nano-block integration process for novel thermoelectric materials

P. Zhu, Y. Masuda, K. Koumoto

Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, 464-8603, Nagoya, Japan

Thermoelectric theory suggests that the ideal thermoelectric materials should have high electric conductivity, high Seebeck coefficient and low thermal conductivity, which is hardly achieved simultaneously in the existing thermoelectric metals and metal oxides so far. In the present study, a novel process (nano-block integration) is proposed and attempted to fabricate the new composites with the so-called artificial lattice alternatively stacking the conductive layers (octahedral CoO2) and insulating layers (silica, etc.). Cobalt hydroxides, Co(OH)2, with well controlled thickness ( nano scale) and crystallized morphologies by adjusting the conditions of an aqueous solution are achieved and subsequently oxidized to form CoO2 sheets with the oxidization agents. A dense silica layer is prepared on CoO2 sheets via the hydrolysis of organosilane. These identical operations are repeated several times and the thin film of composites is obtained on a glass substrate. After an appropriate heat treatment, the thermoelectric properties of the film are extensively investigated. Finally, the possibility of this nano-integration process for new thermoelectric materials will be discussed.