Rana Nabakumar, Mukherjee Suchandra, Singha Pintu, Das Subarna, Bandyopadhyay Sudipta, Banerjee Aritra
Department of Physics, University of Calcutta, 92 A P C Road, Kolkata, West Bengal 700 009, India.
School of Physics, Indian Institute of Science Education and Research, Maruthamala PO, Thiruvananthapuram, Kerala 695 551, India.
J Phys Condens Matter. 2024 Jun 12;36(36). doi: 10.1088/1361-648X/ad5245.
BiTe, an archetypical tetradymite, is recognised as a thermoelectric (TE) material of potential application around room temperature. However, large energy gap (Δ) between the light and heavy conduction bands results in inferior TE performance in pristine bulk-type BiTe. Herein, we propose enhancement in TE performance of pristine-type BiTethrough purposefully manipulating defect profile and conduction band convergence mechanism. Two-type BiTesamples, S1 and S2, are prepared by melting method under different synthesis condition. The structural as well as microstructural evidence of the samples are obtained through powder x-ray diffraction and transmission electron microscopic study. Optothermal Raman spectroscopy is utilized for comprehensive study of temperature dependent phonon vibrational modes and total thermal conductivity (κ) of the samples which further validates the experimentally measured thermal conductivity. The Seebeck coefficient value is significantly increased from 235 μVK(sample S1) to 310 μVK(sample S2). This is further justified by conduction band convergence, where Δis reduced from 0.10 eV to 0.05 eV, respectively. To verify the band convergence, the double band Pisarenko model is employed. Large power factor () of 2190 μWmKand lowerκvalue leading toof 0.56 at 300 K is gained in S2. The obtainedandvalue are among the highest values reported for pristine-type bulk BiTe. In addition, appreciable value of TE quality factor and compatibility factor (2.7 V) at room temperature are also achieved, indicating the usefulness of the material in TE module.
碲化铋（BiTe）作为一种典型的辉碲铋矿，被认为是一种在室温附近具有潜在应用价值的热电（TE）材料。然而，原始块状BiTe中轻、重导带之间的大能量间隙（Δ）导致其热电性能较差。在此，我们提出通过有目的地调控缺陷分布和导带收敛机制来提高原始类型BiTe的热电性能。通过在不同合成条件下采用熔融法制备了两种类型的BiTe样品S1和S2。通过粉末X射线衍射和透射电子显微镜研究获得了样品的结构和微观结构证据。利用光热拉曼光谱对样品的温度依赖声子振动模式和总热导率（κ）进行了综合研究，进一步验证了实验测量的热导率。塞贝克系数值从235 μVK（样品S1）显著增加到310 μVK（样品S2）。这通过导带收敛得到了进一步证实，其中Δ分别从0.10 eV降低到0.05 eV。为了验证能带收敛，采用了双带皮萨连科模型。在S2中获得了2190 μWmK的大功率因数（）和较低的κ值，导致在300 K时的为0.56。所获得的和值是原始类型块状BiTe报道的最高值之一。此外，在室温下还获得了可观的热电品质因数和兼容性因数（2.7 V）值，表明该材料在热电模块中的实用性。
