Raman & infrared study of Bi filled Co₄Sb₁₂

CoSb₃ skutterudites are established thermoelectric materials in the 500-800K temperature range. Undoped and Bi filled CoSb₃ samples were synthesized by induction melting-annealing process and phase confirmation done by X-Ray diffraction. The role of bismuth as a filler in CoSb₃ was investigated by Raman and far infrared reflectance study. It was found that bismuth strengthens Sb vibrations, and can potentially scatter Sb related acoustic phonons effectively. As a result substantial reduction in thermal conductivity may be possible with proper control of Bi filling.