Lorenz number in relation to estimates based on the Seebeck coefficient [electronic resource]

• Ngôn ngữ: eng
• Ký hiệu phân loại: 621.312 Generation, modification, storage
• Mô tả vật lý: Size: p. 49-55 : , digital, PDF file.
• Bộ sưu tập: Metadata
• ID: 255644
• Chủ đề: 1. 30 direct energy conversion; 2. Boltzmann transport theory; 3. Electronic thermal conductivity; 4. First principles calculations; 5. Lorenz number; 6. Thermal conductivity; 7. Thermoelectric

Tóm tắt

Separation of thermal conductivity (k) into its electronic, lattice and other parts is of great importance in understanding heat transport. Commonly, the Wiedemanne?Franz relation is used to obtain the electronic thermal conductivity based on the electrical conductivity and a Lorenz number that is either set to the standard value for metals or using an approximate formula based on the Seebeck coefficient. We used the Boltzmann transport theory to test this formula for realistic electronic structures of thermoelectrics in different scattering regimes. Here, we find that this expression can give values of the Lorenz number that differ infstantially from Boltzmann theory for the range of doping levels important in thermoelectrics. This happens for materials with complex non-parabolic band structures, which are common in high performance thermoelectrics. The results imply that caution should be exercised in the use of this formula in thermoelectrics and other materials that may have complex electronic structures.