Electrical properties and figures of merit for new chalcongenide-based thermoelectric materials

摘要

New Bi-based chalcogenide compounds have been prepared using the plychalcogenide flux technique for crystal growth. These materials exhibit characteristics of good thermoelecric materials. Single crystals of the compounds CsBi_4Te_6 have shown conductivity as highs as 244 S/cm with a p-type thermoelectric power of approx aprox +110 mu V/K at room temperature. A second compound, beta -K_2Bi_8Se_(13) shows lower conductivity approx approx 240 S/cm, but a laerger n-type thermopower approx approx 200 mu V/K. Thermal transport measurements have been performed on hot-pressed pellects of these materials and the results show comparable or lower thermal conductivities than Bi_2Te_3. This improvement may reflect the reduced lattice symmetry of the new chalocogenide thrmoelectrics. The thermoelectric figure of merit for CsBi_4Te_6 reaches ZT approx approx 0.32 at 260K and for beta -K_2Bi_8Se_(13) ZT approx approx .032 at room temperature, indicating that these compounds are viable candidates for thermoelectric refrigeration applications.