Microstructure And Thermoelectric Properties Of La_yTi_0.1Ga_0.1Fe_xCo_4-xSb₁₂ Alloy

The skutterudite has good mechanical properties and thermoelectric properties.It is currently a promising medium-temperature thermoelectric material.High-performance thermoelectric devices require high-performance n-type and p-type skutterudite thermoelectric materials.At present,the ZT and PF of p-type skutterudite thermoelectric materials are significantly lower than that of n-type skutterudites.In order to further improve the thermoelectric properties of p-type skutterudite,the samples of multi-scale structures materials were prepared by melting-spinning and hot-press sintering to reduce the thermal conductivity of the lattice,with the contents of Fe and La filling fraction.The optimum carrier concentration is achieved,which in turn increases the material's power factor and thermoelectricperformance.Inthispaper,themicrostructureof La_0.8Ti_0.1Ga_0.1Fe_xCo_4-x-x Sb₁₂and La_yTi_0.1Ga_0.1Fe_3.5Co_0.5.5 Sb₁₂was characterized by XRD and SEM,and the changing rule was explored.The laser thermal conductivity meter and electrical performance testing instrument were used.The thermoelectric properties of La_0.8Ti_0.1Ga_0.1.1 Fe_xCo_4-x-x Sb₁₂and La_y Ti_0.1Ga_0.1.1 Fe_3.5Co_0.5Sb₁₂have been investigated using laser thermal conductivity meters and electrical test instruments.Studies have shown that when the filling fraction of La is 0.8,when x=3.0 the pure phase of skutterudite was obtained at x=3.0,and FeSb₂,and Ga Sb secondary phases appeared when x?3.3.With the increase of x content,the conductivity gradually increases and the Seebeck coefficient decreases gradually.At x=3.5,the maximum power factor was approximately 36.8 W cm^-1K^-2@773K.The power factor was increased by 23%compared to x=3.0,indicating that adjusting the Fe content significantly improved the electrical performance.With the increase of the content of Fe-substituted Co,the lattice distortion increases,and the thermal conductivity of lattice gradually decreases with the increase of x.The maximum ZT value is 1.16@773K at x=3.5,and ZT_ave=0.76.By calculating the maximum output power density and conversion efficiency,we find that the performance is optimal at x=3.5,at 828 K,?_max=9.5 W cm^-2,and?=11.6%.Research show that the optimum Fe content is x=3.5,when y?0.85,FeSb₂and GaSb second phases appeared when t y?0.8 skutterudite pure phase was obtained.The content of the second phase gradually decreased with the increase of y.With the increase of y fraction,the conductivity gradually decreases,and the Seebeck coefficient is opposite.At y=0.8,0.85,the power factor is fairly 36.8 W cm^-1K^-2.The lattice thermal conductivity does not change significantly with the increase of y,and y=0.85,ZT_ave=0.79.By comparing the maximum output power density and conversion efficiency of alloys with different La-filling amounts,it is found that the performance is optimal at y=0.85,and?_max=10.2 W cm^-2and?=11.8%at 828 K.In summary,the thermoelectric performance is optimal when x=3.5 and y=0.85.