MnCl_(2)掺杂n型多晶SnSe热电性能研究

Study on thermoelectric properties ofn-type polycrystalline SnSe doped with MnCl_(2)

SnSe是一种极具应用潜力的热电材料。采用熔融法结合SPS烧结制备了一系列SnSe_(0.95)-x%(摩尔分数)MnCl_(2)样品,研究了MnCl_(2)掺杂对n型多晶SnSe热电性能的影响。结果表明,所有样品均表现出明显的各向异性,沿平行于烧结压力方向具有更优异的热电性能。MnCl_(2)掺杂量的增加引起样品中Sn相含量变化以及析出SnCl_(2)相,进而影响材料的载流子浓度和迁移率,同时提升样品热激发后的电导率和Seebeck系数。此外,MnCl_(2)掺杂引入的点缺陷和SnCl_(2)析出相,显著增强声子散射,降低材料的热导率。但随着MnCl_(2)掺杂量逐渐增大,材料的热导率缓慢增加。结果,SnSe_(0.95)-0.5%(摩尔分数)MnCl_(2)样品在773 K时获得了1.01的最大ZT值,是未掺杂样品的近22倍。

SnSe has been demonstrated a thermoelectric material with great application potential.In this paper,a series of SnSe_(0.95)-x mol%MnCl_(2)samples were prepared by melting method combined with SPS sintering,and the effect of MnCl_(2)doping on the thermoelectric properties of n-type polycrystalline SnSe was studied.The results show that all the samples exhibit obvious anisotropy,and have better thermoelectric properties along the direction parallel to the sintering pressure.The increase of MnCl_(2)doping concentration causes the change of Sn phase content and the precipitation of SnCl_(2)phase in the sample,thus affecting the carrier concentration and mobility,and improving the conductivity and Seebeck coefficient of the samples after thermal excitation.In addition,the point defects and SnCl_(2)precipitation introduced by MnCl_(2)doping significantly enhance the phonon scattering and reduce the thermal conductivity of the materials.However,the thermal conductivity increases slightly with the increase of MnCl_(2)doping amount.As a result,the SnSe_(0.95)-0.5 mol%MnCl_(2)sample obtains a maximum ZT value of 1.01 at 773 K,which is nearly 22 times that of the undoped sample.