标题： CdSnAs2中闪锌矿-黄铜矿相变的控制用于高功率因子的n型热电材料 显示英文标题

标题： Control of sphalerite-chalcopyrite phase transition in CdSnAs2 for n-type thermoelectrics with high power factor

摘要： 热电（TE）材料的实际应用受到高性能n型材料发展不足的限制，与p型材料相比，n型材料的发展较为滞后。 闪锌矿结构的CdSnAs2因其约0.2 eV的窄带隙和极高的电子迁移率，被认为是热电领域有前景的n型半导体。 在本研究中，我们研究了CdSnAs2的晶体生长、微观结构和热电性能。 与传统的单向熔体生长理论相反，CdSnAs2样品在较高冷却速率下表现出更好的结晶度，而在缓慢冷却的样品中观察到一些裂纹。 热分析表明，在缓慢冷却的情况下，固态后发生了从闪锌矿到黄铜矿的相变，由于相间的晶格失配导致位错和裂纹。 快速冷却的分析表明，过冷降低了凝固温度并形成了适当的微观结构。 因此，以最高冷却速率（7.6 K/min）生长的样品在600 K时实现了3.18 mW/mK^2的超高压因素，并在682 K时达到了峰值zT值0.62。在压因素方面，CdSnAs2超过了传统的二元n型热电材料如SnSe和PbTe，证明CdSnAs2是中温热电应用的高潜力候选材料。 显示英文摘要

摘要： Practical applications of thermoelectric (TE) materials are constrained by less developments of high-performance n-type materials compared to their p-type counterparts. Chalcopyrite CdSnAs2 is a promising n-type semiconductor for thermoelectrics from its narrow bandgap around 0.2 eV and exceptionally high electron mobility. In this study, we investigated the crystal growth, microstructure, and thermoelectric properties of CdSnAs2. Contrary to conventional theory of unidirectional melt growth, CdSnAs2 samples at higher cooling rates exhibited better crystallinity, while some cracks were observed in samples cooled more slowly. Thermal analyses clarified that a phase transition from sphalerite to chalcopyrite occurred after solidification in the case of slow cooling, leading to dislocations and cracks due to the lattice mismatch between phases. The analysis at rapid cooling suggested that supercooling lowers the solidification temperature and produces an appropriate microstructure. Consequently, the sample grown at the highest cooling rate (7.6 K/min) achieved an ultrahigh power factor of 3.18 mW/mK^2 at 600 K and a peak zT of 0.62 at 682 K. In the power factor, CdSnAs2 surpasses conventional binary n-type TE materials such as SnSe and PbTe, proving that CdSnAs2 is a high potential candidate for mid-temperature TE applications.