Thermoelectric materials with high figure of merit, which requires large Seebeck coefficient, large electrical conductivity and low thermal conductivity, are of great importance in solid state cooling and power generation. Solid solution formation is one effective method to achieve low thermal conductivity by phonon scattering due to mass and strain field fluctuation. This type of scattering is maximized in structures containing vacancies. The thermoelectric properties of the vacancy compounds of Ga2Te3 - GaSb are studied in this research. We find that the lattice thermal conductivity is reduced by over an order of magnitude with the addition of only very moderate amounts of Ga2Te3. Additionally, both the carrier type and concentration can be modified with the addition of Ga2Te3. While the vacancy structure induced by the addition of Ga2Te3 to GaSb can effectively reduce phonon conductivity, carrier mobility is also degraded. Thus the optimized thermoelectric properties require careful control of the vacancy content in these solid solutions. The effect of preparation methods on thermoelectric properties of these solid solutions has also been studied. The influence of extrinsic doping and isoelectronic substitution on thermoelectric performance of Ga2Te3 - GaSb is also discussed in this work.
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