Thermoelectric properties of oxide device: (Na/sub 0.95/Ag/sub 0.05/)/sub x/CoO/sub 2$/ -/sub δ//(Nd/sub 0.99/Zr/sub 0.01/)/sub 2/CuO/sub 4-δ/

Abstract

The thermoelectric properties of polycrystalline (Na/sub 1-y/Ag/sub y/)/sub x/CoO/sub 2-/spl delta// and (Nd/sub 1-x/Zr/sub x/)/sub 2/CuO/sub 4-/spl delta// by the conventional solid state reaction method were examined. The electrical resistivity of (Na/sub 1-y/Ag/sub y/)/sub x/CoO/sub 2-/spl delta// shows a metallic temperature dependency, and a p-type conduction is expected according to thermoelectric power measurements. Minimum resistivity, maximum thermoelectric power, minimum thermal conductivity at room temperature, and the maximum figure of merit at 550 K of (N/sub 0.95/Ag/sub 0.05/)/sub x/CoO/sub 2-/spl delta// were 2.1 m/spl Omega//spl middot/cm, 100 /spl mu/VK/sup -1/, 1.6 Wm/sup -1/K/sup -1/, 0.16/spl times/10/sup -3/ K/sup -1/, respectively. On the other hand, (Nd/sub 1-x/Zr/sub x/)/sub 2/CuO/sub 4-/spl delta// shows an n-type behavior. Resistivity, thermoelectric power, thermal conductivity, and the maximum figure of merit at 300 K of (Nd/sub 0.99/Zr/sub 0.01/)/sub 2/CuO/sub 4-/spl delta// were 46 m/spl Omega//spl middot/cm, -300 /spl mu/VK/sup -1/, 6 Wm/sup -1/K/sup -1/, 4.2/spl times/10/sup -5/ K/sup -1/, respectively. A complete thermoelectric device using the p-type and n-type materials was successfully fabricated for the first time, and the performance of the device was evaluated. A maximum output power of the device was 19 /spl mu/W at /spl Delta/T=200 K. The very low output, which is only 1% of the theoretical value, is due to a poor electrical contact to the n-type material.