The influence of rare earth element Tm doping on the thermoelectric properties of Cu2S
Cu2S has low lattice thermal conductivity and narrow band gap width,and its excellent thermoelectric performance,low cost,and non-toxic properties have attracted widespread attention in the research field of thermoelectric materials.The present work adopts a combination of hydrothermal synthesis and vacuum sinte-ring to prepare Cu2S based thermoelectric materials.Through phase and composition characterization,as well as thermoelectric performance testing,the influence of rare earth element Tm doping on the thermoelectric proper-ties of Cu2S based materials has been studied.First-principles calculations are used to develop the band structure and density of states of Cu2S.The results indicate that the hydrothermal synthesis method can obtain Cu31S16 powders,and the phase transformation occurs during the vacuum sintering process,from the original Cu31S16 to Cu2S.Tm element doping can significantly improve the crystallization performance of Cu2S powders,and with the increase of doping content,the agglomeration phenomenon of Cu2S gradually disappears.The Seebeck coef-ficient of Cu2S increases with the increase of Tm doping amount,with Cu2S doped with 2％Tm at a phase tran-sition temperature of 350℃and the Seebeck coefficient reaching a peak of 1589.71 μV/K.With the increase of doping elements and temperature,the electrical conductivity of Cu2S gradually decreases.The thermal conduc-tivity of Cu2S doped with Tm in the medium to high temperature range has a gradual downward trend.The re-sults showed that the figure of merit of Cu2S doped with 2％Tm increases from 0.1 to 0.4,exhibiting an in-crease of 300％.
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