| A growing concern for environmentally friendly devices as well as a need for more efficient materials, has revitalized recently the field of thermoelectricity. Several research groups are investigating new compounds that could replace the established materials Bi2Te 3 and PbTe which have been used for several decades for thermoelectric applications.; A new family of quartenary chalcogenides semiconducting compounds of general formulae AmBnMmQ2m+n (where A is K or Ag, B is Pb or Sn, M is Bi or Sb and Q is S, Se, or Te) was synthesized and characterized. Preliminary measurements show that these narrow band gap semiconductors possess promising transport properties for thermoelectric applications. A wide range of values have been observed for the parameters of interest (the Seebeck coefficient, and the electrical and thermal conductivity) depending on the elements chosen and the values of n and m. Among all the systems investigated, KPb10BiTe12 was chosen for further optimization. The thermal conductivity of this compound can be decreased significantly by increasing the mass fluctuation in the structure via solid solutions. The introduction of Sn as chemical dopant agent increased the figure of merit ZT. Significant differences between measurements of the Seebeck coefficient on cold pressed pellets and ingots were observed and investigated. |
