A process called thermoelectric conversion converts waste heat into electricity. Rare metals are used in the synthesis of thermoelectric conversion devices. They are expensive and most of the time use toxic materials. These converters have been limited in their use. One of the drawbacks of oxide-based thermoelectric materials is that they don't have enough evidence of their stability at high temperatures.
A team led by Professor Hiromichi Ohta at the Research Institute for Electronic Science at Hokkaido University has created a barium oxide thermoelectric converter that can be used at temperatures up to 600C.
An electric current is generated when there is a temperature difference between conducting and non-conducting materials. The thermoelectric figure of merit ZT is the most important figure for efficiency. Many candidates have high ZT but their stability at high temperatures was not documented.
Hiromichi Ohta's group has been working on films for over 20 years. The team wanted to examine the thermal and chemical stability of these films, as well as measure their ZT values. The films were analyzed for their structure, resistivity, and thermal Conductivity.
The strontium oxide films were only stable until 350C, while the barium oxide films were stable until 600C.
Hiromichi Ohta said that their study showed that barium oxide films would be good candidates for high- temperature thermoelectric conversion devices. They are environment friendly and have the potential to be deployed wide.
More information: Xi Zhang et al, Ba1/3CoO2: A Thermoelectric Oxide Showing a Reliable ZT of ~0.55 at 600 °C in Air, ACS Applied Materials & Interfaces (2022). DOI: 10.1021/acsami.2c08555 Journal information: ACS Applied Materials and Interfaces
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