Thermoelectric properties of Ln-Ni-O (Ln : lanthanoid) systems

In order to discover a new n-type oxide possessing good thermoelectric properties, high throughput screening of (La,M)NiO₃ systems has been carried out. Aqueous solutions of metal nitrates were used as starting materials in this screening. One precursor library with 100 samples composed of different compositions was prepared on a 100 × 100 mm alumina plate within an hour. After heating the libraries at temperatures higher than 973 K, evaluation of thermoelectric power of the samples was performed using a high-speed two terminal method (´Seebeck tester´). It is found from this screening that Bi-, Na-, and K-substitution for La is effective to improve thermoelectric power in the (La, M)NiO₃ systems. A hot pressed sample of La_0.9Bi_0.1NiO₃ shows metallic thermoelectric properties, namely both thermoelectric power and electrical resistivity increase with temperature and are- 30 μV/K and 1.1 mΩ cm at 973 K in air, respectively.