La 掺杂 P 型 Ce_yFe₃CoSb₁₂热电材料及涂层的热电性能

During the use of fossil fuels, about two-thirds of the energy that is discharged into the environment in the form of waste heat are barely utilized and cause considerable environmental pollution and intense CO₂ emission. Thermoelectric materials directly convert heat energy to electricity, thus, improving the utilization efficiency of fossil energy and reducing environmental pollution. Skutterudite CoSb₃ has been widely studied as one of the materials for thermoelectric applications in the middle-temperature region. CoSb₃-based skutterudites are narrow bandgap semiconductors with a high-electrical conductivity and Seebeck coefficient. Meanwhile, thermoelectric performance of bulk CoSb₃ has been considerably improved via doping and design of nano structures. Herein, P-type CoSb₃ was synthesized via melt-annealing-spark plasma sintering process. The effect of Ce-doping content on microstructure and thermoelectric properties of CoSb₃ and the effect of La doping on decoupled thermoelectric performance were studied. Compared with Ce_0.8Fe₃CoSb₁₂, the Seebeck coefficient of La_0.1Ce_0.8Fe₃CoSb₁₂ increased with temperature, electrical resistivity decreased from 25 μΩ·m to 15 μΩ·m at 300 K, and power factor simultaneously increased from 480 μW/(m·K²) to 642 μW/(m·K²) at 673 K. The La_0.1Ce_0.8Fe₃CoSb₁₂ thermal conductivity decreased with La or Ce doping to ~1 W/(m·K), and the corresponding thermoelectric figure of merit reached 0.45 at 723 K in the temperature range from 300 K to 723 K. Al-Ni coating was deposited on the sintered bulk skutterudite via magnetron sputtering method. It was demonstrated that the coating did not degrade the thermoelectric performance, while the coating elements were uniformly distributed across the sintered bulk La_0.1Ce_0.8Fe₃CoSb₁₂. The welding behavior of P-type La_0.1Ce_0.8Fe₃CoSb₁₂ was studied using a Ag₄₀Cu₆₀ solder and a Mo₅₀Cu₅₀ electrode sheet. The interface of this thermoelectric material was prone to cracking and pore formation, while the elements at the interface have not demonstrated remarkable diffusion. This indicates an efficiency of the interface bonding, which may be used in the fabrication technologies of thermoelectric devices.