Study on thermoelectric properties of n-type polycrystaliine SnSe doped with MnCl2.

SnSe has been demonstrated a thermoelectric material with great application potential. In this paper, a series of SnSe_0.95-x mol% MnCl₂ samples were prepared by melting method combined with SPS sintering, and the effect of MnCl₂ doping on the thermoelectric properties of n-type polycrystalline SnSe was studded. 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 MnCl₂ doping concentration causes the change of Sn phase content and the precipitation of SnCl2 phase in the sample, thus affecting the carrier concentration and mobility, and improving the conductivity and See beck coefficient of the samples after thermal exaction. In addition, the point defects and SnCl₂ precipitation introduced by MnCl₂ doping significantly enhance the phonon scattering and reduce the thermal conductivity of the materials. However, the thermal conductivity increases slightly with the increase of MnCl₂ doping amount. As a result, the SnSe0.9--0.5 mol% MnCl₂ sample obtains a maximum ZT value of 1.01 at 773 K, which Is nearly 22 times that of the undead sample. [ABSTRACT FROM AUTHOR]