Microstructure And Thermoelectric Properties Of SiC Doped N-type Pseudoternary Semiconductor Materials

Pseudoternary thermoelectric materials have excellent thermoelectric properties at room temperature,but their thermoelectric conversion efficiency is low.How to improve the thermoelectric properties of pseudoternary thermoelectric materials is always the focus of research.Selecting the most suitable preparation method is also one of the ways to improve the thermoelectric properties.Mechanized alloy method can make the material size uniform,structural and strong energy better improve the thermoelectric properties.In this paper,N-type pseudo ternary semiconductor materials were prepared by mechanized alloy method.In the pseudo ternary thermoelectric materials,the SiC concentration was 0 wt%,0.5 wt%,1.0 wt% and 1.5 wt%,and mixed with ball mill for three hours.After mixing,block samples of SiC doped n-type pseudo ternary semiconductor materials were prepared by hot pressing.The microstructure was analyzed by X-ray diffractometer,scanning electron microscope,and the thermoelectric properties of SiC doped ternary semiconductor materials were analyzed by testing the conductivity,Seebeck coefficient and thermal conductivity of the materials.The microstructure analysis shows that after sintering n-type undoped pseudoternary powder,the XRD diffraction peak becomes significantly higher,and the half-height width becomes narrower,the grains grow,and the interatomic bonding becomes closer.According to the XRD pattern,when the SiC concentration is 0.5 wt %,the diffraction peak becomes higher and the half-height width becomes narrower with the increase of sintering temperature,indicating that the lattice degree of the material increases with the increase of sintering temperature.According to SEM results,with the increase of sintering temperature can promote the growth of grains,the lamellar structure,indicating that the gap between grains decreases,which is consistent with XRD results.The thermal parameters of the test result shows that with the increase of concentration of SiC,the absolute value of Seebeck coefficient decreases after increasing first,electrical conductivity and thermal conductivity increases with the concentration of SiC were reduced gradually,the reason is that SiC concentration increase lead to defective material inside the introduction of more effective quality level increases,at the same time,the scattering effect of carrier in the growing.With the increase of sintering temperature from 200?,the degree of crystallization is enhanced,and the scattering effect of phonons and electrons is weakened.When the sintering temperature is above 340?,the closed void inside the material expands significantly,resulting in the absolute value of Seebeck coefficient and thermal conductivity of the material increase first and then decrease,while the electrical conductivity increases gradually.The Z value of the material decreases with the increase of SiC concentration and increases with the increase of sintering temperature.Both SiC concentration and sintering temperature change the thermoelectric properties of SiC doped N-type pseudoternary semiconductor materials.