Microstructure And Thermoelectric Properties Of P-type Gd-doped Pseudo-ternary Semiconductor Refrigeration Materials

Semiconductor thermoelectric devices can mutually convert electrical energy and thermal energy through internal carrier transport,and are used in thermoelectric power generation and thermoelectric cooling.But its conversion efficiency is low.How to optimize the thermoelectric performance of semiconductor thermoelectric materials is the fundamental problem to be solved first to improve the thermoelectric conversion efficiency of semiconductor devices.The doping method can change the lattice structure and electronic structure of the material,thereby improving the thermoelectric performance.It is the focus of this paper to reveal the thermoelectric performance optimization mechanism of thermoelectric materials by studying the influence of microstructure and carrier transport law on thermoelectric properties.In this paper,the P-type Gd-doped pseudo-ternary semiconductor refrigeration material(PTSRM)is prepared by the mechanical alloying sintering hot pressing method.Analyze the microstructure of the material through X-ray diffraction experiment and scanning electron microscopy experiment,use Hall effect test to analyze the change law of material carrier concentration and mobility,and analyze P-type Gd by testing electrical conductivity,Seebeck coefficient and thermal conductivity The change law of thermoelectric properties of doped PTSRM.XRD test and SEM test were performed to analyze the influence of sintering and hot pressing parameters on the microstructure of the material.XRD analysis shows that the Gd element peak disappears after ball milling of the powder material,and alloying is achieved.The diffraction peak of the powder sample after sintering becomes higher and narrower,and the sample crystallizes stronger;when the hot pressing parameters of the bulk material are constant,The higher the hot-pressing parameter,the sharper the diffraction peak of the sample,indicating that the degree of crystallization of the material is enhanced;SEM analysis shows that within a certain range of hot-pressing parameters,as the hot-pressing parameter increases,the inter-grain pores decrease and the crystal grains Gathering and growing up,the layered structure is more obvious.The results of the Hall effect analysis show that under the condition of a certain thermal pressure parameter,with the increase of the Gd doping concentration,the carrier concentration first decreases and then slightly increases,while the carrier mobility first increases significantly and then slightly There is a reduction.Test the Seebeck coefficient,electrical conductivity and thermal conductivity of P-type Gd-doped PTSRM to analyze the effect of doping concentration and hot pressing parameters on the thermoelectric properties of the material.The results show that the Seebeck coefficient,electrical conductivity and thermal conductivity increase firstly and then decrease with the increase of Gd doping concentration.With the increase of thermal pressure parameters,the electrical conductivity and thermal conductivity gradually increase,and the Seebeck coefficient affects It's not big.The power factor and ZT value of P-type Gd-doped PTSRM first increase and then decrease with the increase of Gd doping concentration.When the doping concentration is 1.5% and the hot pressing temperature is 200 ?,the power factor and ZT value are both Reach the maximum value,which is determined by the change law of Seebeck coefficient,electrical conductivity and thermal conductivity.