Ryś Wojciech, Lutsyk Iaroslav, Szałowski Karol, Ster Maxime Le, Rogala Maciej, Piskorski Michał, Krukowski Paweł, Dąbrowski Paweł, Dunal Rafał, Nadolska Aleksandra, Przybysz Przemysław, Toczek Klaudia, Kozłowski Witold, Kowalczyk Paweł J
Department of Solid State Physics, Faculty of Physics and Applied Informatics, University of Lodz, Pomorska 149/153, 90-236, Łódź, Poland.
Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.
Sci Rep. 2025 May 7;15(1):15936. doi: 10.1038/s41598-025-00907-5.
This study examines the thermal stability and structural behavior of bismuth chloride telluride BiTeCl, a layered thermoelectric material with significant potential for energy conversion applications. Our investigations reveal that the chlorine-terminated surface exhibits poorer quality and increased defectivity compared to the tellurium-terminated side. The crystals were subjected to thermal annealing up to 520 K and green laser irradiation. Through techniques such as low-energy electron diffraction (LEED) and X-ray photoelectron spectroscopy (XPS), we found that while annealing enhances the crystallinity of the chlorine side up to 470 K, it ultimately suffers from thermal degradation above this temperature. The event leads to transformation into bismuth telluride - BiTe characterized by a lower BE shift of the Bi and Te bands by ~ 0.35 eV. The identity of the product was later confirmed via Raman spectroscopy while irradiating it with little laser power. With an increase in the power to 3.1 mW, it was however observed that the samples become locally modified undergoing similar degradation as during the annealing. The research demonstrates and characterizes the phenomena occurring during the decomposition either via irradiation or annealing. The explanation of such phenomena is then proposed based on the results of our theoretical DFT calculations. Additionally, we assess the usefulness of BiTeCl as a thermoelectric material, compare it in regard to the literature, and suggest new potential applications that may benefit from the transformation into BiTe.
本研究考察了碲化铋氯（BiTeCl）的热稳定性和结构行为，BiTeCl是一种具有重要能量转换应用潜力的层状热电材料。我们的研究表明，与碲端相比，氯端表面质量较差且缺陷增多。对晶体进行了高达520 K的热退火和绿色激光辐照。通过低能电子衍射（LEED）和X射线光电子能谱（XPS）等技术，我们发现虽然退火在470 K以下提高了氯端的结晶度，但在此温度以上最终会发生热降解。该过程导致转变为碲化铋（BiTe），其特征是Bi和Te能带的结合能（BE）位移降低了约0.35 eV。产物的身份随后通过拉曼光谱在低激光功率辐照下得到证实。然而，当功率增加到3.1 mW时，观察到样品发生局部改性，经历了与退火过程中类似的降解。该研究展示并表征了通过辐照或退火分解过程中发生的现象。然后根据我们的理论密度泛函理论（DFT）计算结果对这些现象进行了解释。此外，我们评估了BiTeCl作为热电材料的实用性，与文献进行了比较，并提出了可能受益于向BiTe转变的新潜在应用。
