CsCu5S3: Promising Thermoelectric Material with Enhanced Phase Transition Temperature
1Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry , Beijing Normal University , Beijing 100875 , People's Republic of China.
Inorganic Chemistry
|January 9, 2019
Summary
We discovered CsCu5S3, a new thermoelectric material with a high phase transformation temperature, overcoming the limitations of Cu2S. This material shows significantly enhanced thermoelectric performance.
Area of Science:
- Materials Science
- Solid State Chemistry
Background:
- Copper sulfide (Cu2S) is a promising thermoelectric material due to its low cost and abundance.
- Cu2S exhibits phase transformations at low temperatures (starting at 370 K), leading to decomposition and reliability issues, hindering its practical application.
Purpose of the Study:
- To discover and characterize a novel thermoelectric material with improved phase stability compared to Cu2S.
- To investigate the structural and thermoelectric properties of the newly discovered CsCu5S3.
Main Methods:
- Single crystal X-ray diffraction was used to determine the crystal structures of the two phases of CsCu5S3.
- Thermoelectric property measurements were conducted to evaluate the figure of merit (ZT).
- Theoretical calculations were performed to understand the relationship between structure and electronic properties.
Main Results:
- CsCu5S3 was discovered, exhibiting a significantly higher phase transformation temperature (823 K) compared to Cu2S.
- Two phases, orthorhombic (o-CsCu5S3) and tetragonal (t-CsCu5S3), were identified, both constructed from Cu4S4 columnar units.
- Remarkable thermoelectric figure of merit (ZT) values were achieved: 0.46 at 800 K for o-CsCu5S3 and 0.56 at 875 K for t-CsCu5S3, representing substantial enhancements over Cu2S.
Conclusions:
- CsCu5S3 demonstrates superior phase stability and enhanced thermoelectric performance compared to Cu2S, making it a promising candidate for advanced thermoelectric applications.
- The unique Cu4S4 columnar structure and its arrangement in different phases are key to the high thermoelectric performance of CsCu5S3.
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