Abstract Herein the effect of Co element doping on the thermoelectric properties of n-type Bi2(Te0.97Se0.03)3 alloys fabricated by a melting synthesis technique followed by spark plasma sintering was reported. The micro-morphology and composition of the specimens was characterized by means of X-ray diffraction and scanning electron microscopy. The electrical and thermal properties of (Bi1-xCox)2(Te0.97Se0.03)3 with x = 0%, 2%, 4% and 8% were measured from 298K to 473K. We found that (i) the micro-scale secondary phase CoTe2 was embedded into the matrix due to the low solubility of Co element; (ii) Co doping generally improved the effective mass due to the scattering by local magnetic moments carried by Co ion and practically retained the carrier concentration, thereby yielding the higher Seebeck coefficient; (iii)both the electronic and lattice thermal conductivity decreased simultaneously by introducing the hierarchical defects (point defects and the micro-scale defects). Specifically, the x = 8% sample obtained a minimum thermal conductivity ~1.26 Wm−1K−1 at 398K. This results in a maximum ZT value of ~0.77, approximately ~20% higher than that of pristine Bi2(Te0.97Se0.03)3.

中文翻译：

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Co掺杂n型Bi2(Te0.97Se0.03)3中电热效应的协同调节导致优化的热电性能

摘要 本文报道了Co元素掺杂对通过熔融合成技术然后放电等离子烧结制备的n型Bi2(Te0.97Se0.03)3合金的热电性能的影响。通过X射线衍射和扫描电子显微镜表征样品的微观形态和组成。(Bi1-xCox)2(Te0.97Se0.03)3 (Bi1-xCox)2(Te0.97Se0.03)3 (x = 0%, 2%, 4% 和 8%) 的电学和热学性质在 298K 至 473K 范围内测量。我们发现 (i) 由于 Co 元素的低溶解度，微尺度的第二相 CoTe2 被嵌入到基体中；(ii) 由于 Co 离子携带的局部磁矩的散射，Co 掺杂通常提高了有效质量，实际上保持了载流子浓度，从而产生了更高的塞贝克系数；(iii) 通过引入分层缺陷（点缺陷和微尺度缺陷），电子和晶格热导率同时降低。具体而言，x = 8% 的样品在 398K 下获得了 ~1.26 Wm-1K-1 的最小热导率。这导致最大 ZT 值约为 0.77，比原始 Bi2(Te0.97Se0.03)3 高约 20%。