Efficient Si Doping Promoting Thermoelectric Performance of Yb-Filled CoSb₃-Based Skutterudites

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• Nanocomposites are crucial for enhancing thermoelectric materials.
• Filled skutterudites, like Yb$_{0.3}$Co$_{4}$Sb$_{12}$, show promise for thermoelectric applications.
• Optimizing thermoelectric performance requires careful material design.

Purpose of the Study:

• To investigate the effect of silicon (Si) doping on the thermoelectric properties of Yb$_{0.3}$Co$_{4}$Sb$_{12}$ nanocomposites.
• To understand the role of in-situ precipitated CoSi nanoparticles in influencing thermoelectric performance.
• To evaluate the overall thermoelectric figure of merit (ZT) enhancement.

Main Methods:

• Synthesis of Yb$_{0.3}$Co$_{4}$Sb$_{12}$ nanocomposites with varying Si doping levels.
• Characterization of the microstructure and phase composition, including the formation of CoSi nanoparticles.
• Measurement of thermoelectric transport properties (Seebeck coefficient, electrical conductivity, thermal conductivity) as a function of temperature.
• Calculation of the thermoelectric figure of merit (ZT).

Main Results:

• Si doping led to the in-situ precipitation of CoSi nanoparticles and a reduced Yb filling fraction.
• CoSi nanoparticles enhanced the power factor and reduced electronic thermal conductivity.
• CoSi nanoparticles effectively scattered phonons, mitigating increased lattice thermal conductivity.
• Despite adverse effects from YbSb$_{2}$ phases, a peak ZT of 1.37 at 823 K was achieved.
• The average ZT (ZT$_{ave}$) increased by 21% for the Yb$_{0.3}$Co$_{4}$Sb$_{12}$/0.1Si sample.

Conclusions:

• Silicon doping is an effective strategy to enhance the thermoelectric performance of Yb$_{0.3}$Co$_{4}$Sb$_{12}$ nanocomposites.
• The synergistic effects of CoSi nanoparticles and controlled carrier concentration are key to improved thermoelectric efficiency.
• The developed nanocomposites demonstrate significant potential for waste heat recovery applications.