Electronic structure and thermopower of Ni(Ti0.5Hf0.5)Sn and related half-Heusler phases -: art. no. 045121
Electronic structure and thermopower of Ni(Ti0.5Hf0.5)Sn and related half-Heusler phases -: art. no. 045121
复制标题
DOI：
10.1103/physrevb.73.045121
复制
发表时间：
2006-01-01
影响因子：
3.7
通讯作者：
Scherrer, H
中科院分区：
文献类型：
--
作者：
Chaput, L;Tobola, J;Scherrer, H
本文研究了Ni(Ti0.5Hf0.5)Sn及相关半heusler化合物的电子结构和热电性能。两种不同的方法被用来计算电子结构，即有序化合物的全势线性化增广平面波方法和无序合金的相干势近似中的Korringa-Kohn-Rostoker方法。我们表明，如果比较两种情况下得到的态密度，这些方法给出了非常接近的结果。此外，在母化合物合金化过程中，没有发现能带结构的特殊性，因此实验报道的Ni(Ti0.5Hf0.5)Sn相对于NiTiSn或NiHfSn的大热功率值并不是源于电子结构行为。对不同的半heusler化合物进行的热功率计算表明，载流子浓度本身可能是Ni(Ti0.5Hf0.5)Sn以及其他半heusler相的大热功率的主要原因。因此，塞贝克系数的大负值并不局限于某些特定的半赫斯勒半导体，而似乎是具有中等低载流子浓度的n型样品的规律。
In this paper we investigate the electronic structure and the thermopower for Ni(Ti0.5Hf0.5)Sn and related half-Heusler compounds. Two different methods have been used to calculate the electronic structure, i.e., full potential linearized augmented plane wave method for ordered compounds and the Korringa-Kohn-Rostoker method within the coherent potential approximation for disordered alloys. We show that these methods give very close results if comparing the density of states obtained in both cases. Moreover, no peculiarities in the band structure have been revealed upon alloying the parent compounds and therefore the large value of the thermopower reported experimentally for Ni(Ti0.5Hf0.5)Sn with respect to NiTiSn or NiHfSn, does not have an origin in the electronic structure behavior. The thermopower calculations performed for different half-Heusler compounds rather suggest that the carrier concentration itself could be predominantly responsible for the large thermopower in Ni(Ti0.5Hf0.5)Sn as well as in other half-Heusler phases. Therefore, the large negative values of the Seebeck coefficient are not limited to some specified half-Heusler semiconductors but seem to be the rule for the n-type samples with moderately low carrier concentrations.