Improvement of thermoelectric properties for half-Heusler TiNiSn by interstitial Ni defects
Improvement of thermoelectric properties for half-Heusler TiNiSn by interstitial Ni defects
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DOI：
10.1063/1.3633518
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发表时间：
2011-09-15
影响因子：
3.2
通讯作者：
Takeuchi, Tsunehiro
中科院分区：
文献类型：
--
作者：
Hazama, Hirofumi;Matsubara, Masato;Takeuchi, Tsunehiro
为了研究非化学计量比Ti-Ni-Sn半Heusler热电材料中随机分布的缺陷与热电性能的关系，我们合成了非化学计量比Ti-Ni-Sn半Heusler热电材料。Ti-Ni-Sn组成的微小变化引起热导率的显著变化。过量含量的Ni在室温下实现2.93W/mK的低热导率，同时保持高功率因数。低热导率源于由过量含量的Ni产生的缺陷。为了研究详细的缺陷结构，我们进行了第一性原理计算，并与x射线光电子能谱测量进行了比较。基于这些分析，我们得出结论，多余的Ni原子随机占据的空位在半Heusler结构，发挥声子散射中心，导致显着改善的品质因数没有任何昂贵的重元素，如Zr和Hf的替代。(C)2011年美国物理学会。[doi：10.1063/1.3633518]
We have synthesized off-stoichiometric Ti-Ni-Sn half-Heusler thermoelectrics in order to investigate the relation between randomly distributed defects and thermoelectric properties. A small change in the composition of Ti-Ni-Sn causes a remarkable change in the thermal conductivity. An excess content of Ni realizes a low thermal conductivity of 2.93 W/mK at room temperature while keeping a high power factor. The low thermal conductivity originates in the defects generated by an excess content of Ni. To investigate the detailed defect structure, we have performed first-principles calculations and compared with x ray photoemission spectroscopy measurement. Based on these analyses, we conclude that the excess Ni atoms randomly occupy the vacant sites in the half-Heusler structure, which play as phonon scattering centers, resulting in significant improvement of the figure of merit without any substitutions of expensive heavy elements, such as Zr and Hf. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3633518]