Thermoelectric Property Studies on Lead Chalcogenides, Double-filled CobaltTri-Antimonide and Rare Earth-Ruthenium-Germanium.

[摘要] Motivated by the energy applications of thermoelectrics (TE) such as power generationand refrigeration, my research goal is to develop novel materials with high dimensionlessfigure-of-merit ZT. Thermoelectric materials are characterized over a broad temperaturerange from 2 K to 800 K. According to the definition of ZT (=S2σΤ/κ where S is theSeebeck coefficient, σ the electrical conductivity, κ the thermal conductivity, and T theabsolute temperature), reducing thermal conductivity κ increases ZT. However, it ischallenging to tailor material structures to enhance acoustic phonon scattering withoutimpeding charge transport. We investigated three types of solid-state compounds: leadchalcogenides, filled skutterudites and ternary germanides, for their structural, electronic,thermal, and magnetic properties. For lead chalcogenides, nanoparticles embedded in thelattice enhance the mid- to long-wavelength phonon scattering, significantly reducinglattice thermal conductivity κL (~ 0.4 Wm-1K-1 at 300 K for PbTe with 8% PbS). Thesenanostructured PbTe-based alloys exhibit the highest ZT of approximately 1.5. For n-typefilled skutterudites, ZT close to 1.4 is achieved by placing Ba and Yb into the interstitialvoid of CoSb3. Rare-earth ruthenium germanium compounds of the compositionR3Ru4Ge13 have the cage-like structure similar to filled skutterudites, resulting inrelatively low κL (~ 2 Wm-1K-1 at 300 K). They could potentially be developed into a newclass of prospective TE materials.

[发布机构] University of Michigan

[效力级别] Physics

[关键词] Thermoelectrics;Physics;Science;Physics