High-throughput screening of thermoelectric oxides and power generation modules consisting of oxide unicouples
Year: 2004
Type: article
Abstract: A high-throughput screening technique has been developed and utilized in the discovery of a new n-type oxide possessing good thermoelectric properties. With this technique, 1000 samples can be prepared via a sol–gel method and their Seebeck coefficient ( S ) evaluated all within a day. For evaluation of S , a 'Seebeck tester' consisting of two pairs of thermocouples, a heater and a voltage meter, was developed. S values measured using the Seebeck tester more or less coincide with those using a conventional method. The validity of this technique was proven by Ca–Co–O and Na–Co–O systems. Screening ternary systems consisting of 3d transition metals using this technique showed LaNiO 3 to possess the desired n-type properties. Electrical resistivity (ρ) of this oxide is favourably quite low; however, S is as low as –25 µV K −1 at high temperature. To enhance the thermoelectric properties of LaNiO 3 , high-throughput screening was employed to examine candidates from the metal ternary systems La 1– x M 1 x NiO 3 and LaNi 1– x M 2 x O 3 . Bi substitution in the La 1– x M 1 x NiO 3 systems and Cu substitution in the LaNi 1– x M 2 x O 3 systems were found to be effective for improvement of S and ρ, respectively. A thermoelectric unicouple composed of p-type Ca 3 Co 4 O 9 (Co-349) and n-type LaNiO 3 (Ni-113) bulks was constructed. Open-circuit voltage ( V o ) of the unicouple reaches 100 mV at 1073 K on the hot side ( T H ) with a temperature difference (Δ T ) of 500 K in air. Resistance of the unicouple ( R I ) is 26 mΩ at 1073 K in air and increases with increase in temperature. The V o values are consistent with those calculated using S values for each oxide leg. Maximum power ( P max ), which was evaluated using the formula P max = V 2 o /4 R I , is 94 mW at 1073 K (Δ T = 500 K) and increases with temperature. This value corresponds to a volume power density of 660 mW cm −3 .
Authors: R Funahashi, M Mikami, S Urata, M Kitawaki, T Kouuchi, K Mizuno
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2012753498