Abstract

As a kind of high temperature thermoelectric material, TiNiSn compound has the characteristics of high power factor and high thermal conductivity. Its thermoelectric performance is largely limited by the high thermal conductivity. In this paper, TiNiFexSn(x=0-0.05) samples are prepared by melt spinning combined with spark plasma sintering method. The results show that there are nanocrystals existed in the samples with a size of around 200nm. The grain size of the samples is refined through the melt-spinning process, and the lattice thermal conductivity is lower compared with the arc-melted samples. With the increase of Fe content, the lattice thermal conductivity of TiNiFexSn samples decreases, reaching a minimum value of 3.31W/mK when x=0.02, which is 44% lower than that of TiNiSn matrix. The carrier concentration of TiNiFexSn samples increases due to the doping of Fe, resulting in an increase of electrical conductivity and decrease of Seebeck coefficient and finally improvement of the power factor. The maximum zT value of TiNiFe0.03Sn sample is 0.54 at 900K, which is 35% higher than that of TiNiSn samples. This work shows that the melt spinning and magnetic Fe doping can effectively improve the thermoelectric properties of TiNiSn.

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