Improving Thermoelectric Properties by High Temperature Annealing

Technology #11551

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FIG. 4 is a flow chart depicting various steps in another embodiment of a method of the invention for improving thermoelectric properties of alloysFIG. 2A schematically illustrates a few grains of an alloy sample prior to application of the method described in FIG. 1FIG. 2B schematically illustrates the grains of FIG. 2 after application of a high temperature annealing step according to the method of FIG. 1 has caused melting of peripheral layers of the grains,FIG. 2C schematically illustrates the grains of FIG. 3 after solidification of the melted grain portions,
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Inventors
Professor Gang Chen
Department of Mechanical Engineering, MIT
External Link (web.mit.edu)
Professor Zhifeng Ren
Boston College
External Link (mynsm.uh.edu)
Hohyun Lee
Department of Mechanical Engineering, MIT
Shankar Kumar
Boston College
Managed By
Christopher Noble
MIT Technology Licensing Officer - Clean and Renewable Energy
Patent Protection

Thermoelectric Properties by High Temperature Annealing

US Patent 7,591,913

Applications

Thermoelectric properties of alloys are improved through high temperature annealing in this technology. Materials with high thermoelectric properties are used in cooling and power generation applications.

Problem Addressed

The performance of thermoelectric devices is limited to the thermoelectric figure-of-merit (Z). Therefore to improve the performance of thermoelectric devices, Z has to be improved. This technology improves Z in alloys (metals or non-metals) by annealing them one or more times.

Technology

Alloys that have desirable thermoelectric properties are submitted to high temperatures between the solidus- where the alloy is completely solid- and the liquidus- where the alloy is completely liquid and then cooled again. Submitting a multicrystalline alloy to this process at least once allows portions of the alloy to melt and form new compositions (second phases), which create more grain boundaries. The process can be repeated to create three or more phases. An increased number of grain boundaries increases the phonon scattering and allows the material to exhibit a Z close to a superlattice structure.

Advantages

  • Improves thermoelectric properties