Chatterjee Arindom, El Sachat Alexandros, Sotomayor Torres Clivia M, Santiso José, Chavez-Angel Emigdio
Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC, Barcelona Institute of Science and Technology (BIST), Bellaterra 08193, Spain.
Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "Demokritos", Athens 15341, Greece.
ACS Appl Energy Mater. 2024 May 14;7(10):4504-4512. doi: 10.1021/acsaem.4c00551. eCollection 2024 May 27.
In this study, we present a comprehensive analysis of the thermoelectric (TE) properties of highly -axis-oriented thin films of layered misfit cobaltates BiSrCoO. The films exhibit a high -axis orientation, facilitating precise measurements of electronic transport and TE properties along the - crystallographic plane. Our findings reveal that the presence of nearly stoichiometric oxygen content results in high thermopower with metallic conductivity, while the annealing of the films in a reduced oxygen atmosphere eliminates their metallic behavior. According to the well-established Heike's limit, the thermopower tends to become temperature independent when the thermal energy significantly exceeds the bandwidth, which provides a rough estimation of charge carrier density by using the Heike's formula. This observation suggests that the dominant contribution to the thermopower comes from the narrow Co-t bands near the Fermi energy. Our study demonstrates that the calculated thermopower value using Heike's formula, based on the Hall electron density of the BiSrCoO thin films at 300 K, aligns well with the experimental results, shedding light on the intriguing TE properties of this family of layered cobaltate oxide films.
在本研究中，我们对层状失配钴酸盐BiSrCoO高度c轴取向薄膜的热电（TE）性质进行了全面分析。这些薄膜呈现出高度c轴取向，便于沿c晶面精确测量电子输运和TE性质。我们的研究结果表明，接近化学计量比的氧含量会导致具有金属导电性的高热电势，而在低氧气氛中对薄膜进行退火会消除其金属行为。根据已确立的海克极限，当热能显著超过带宽时，热电势趋于与温度无关，这可通过使用海克公式对载流子密度进行粗略估计。这一观察结果表明，对热电势的主要贡献来自费米能级附近狭窄的Co - t能带。我们的研究表明，基于BiSrCoO薄膜在300 K时的霍尔电子密度，使用海克公式计算得到的热电势值与实验结果吻合良好，这为这类层状钴酸氧化物薄膜有趣的TE性质提供了线索。
