Thermoelectrics : material advancements and market applications

Thermoelectric properties have been known since the initial discovery in 1821 by Thomas Seebeck, who found that a current flowed at the junction of two dissimilar metals when placed under a temperature differential. This was followed by the discovery in 1834 by John Peltier, that the inverse was also true. That is, that a current applied to two dissimilar metals would yield a temperature differential. Interest in thermoelectrics laid dormant for almost 100 years and were primarily a laboratory curiosity. That interest was revived in the early 1900s with applications for remote power generation aboard satellites and several military applications. Thermoelectric devices, such as beverage coolers or thermocouples for temperature sensors, that tried to make use of these characteristics shortly followed. However, commercial success soon slowed down as efficiencies of the materials were not conducive to profitability. The effectiveness of a thermoelectric was described by a dimensionless figure of merit given by ZT=(S2a/ke+kp)T, where S is the Seebeck coefficient, T is the operational temperature, a is the electrical conductivity, ke is the electron contribution to thermal conductivity, and kp is the thermal conductivity due to phonon propagation across a crystal lattice. From the mid-1940s until the 1970s there was very slow progress in increased thermoelectric material efficiency, which culminated in a ZT=1 with (Bi2Te3). For approximately 30 years progress stagnated. In 1993, however, new ideas emerged that called for the fabrication of low dimensional structures to enhance electron conductivity while inhibiting phonon contribution to thermal conductivity. Advancements in material efficiency have made great progress since then.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Materials Science and Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2007

Author dc:creator

• Monreal, Jorge

Advisor dc:contributor.advisor

• Gang Chen.

• Materials Science and Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/42156

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/42156