Characterization of bismuth telluride aerogels for thermoelectric applications
- PDF / 1,077,070 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 59 Downloads / 298 Views
Characterization of bismuth telluride aerogels for thermoelectric applications Wenting Dong1, Wendell Rhine1, Greg Caggiano1, Owen R. Evans1, George Gould1, John White2, Jeff Sharp2, Pat Gilbert2, Shreyashi Ganguly3, Stephanie L. Brock3 1 Aspen Aerogels, Inc., Northborough, MA 01532, USA 2 Marlow Industries, Inc., Dallas, TX75238, USA 3 Wayne State University, Detroit, MI 48202, USA ABSTRACT Refrigeration, air conditioning, and other cooling requirements in buildings, industry, and transportation sectors account for about 10 quads of U.S. primary energy consumption. Therefore, advanced technologies for space cooling in buildings and vehicles – as well as for refrigeration in residential, commercial, and industrial applications – that are more energy efficient, avoid net direct greenhouse gas emissions, reduce lifecycle costs, and can impact large markets are needed. Although current technologies are reaching their efficiency limits, thermoelectric (TE) materials can be used for cooling applications and have potential for significant improvements. Compared to traditional bulk phase TE materials, literature results suggest that nanometer-scale materials allow additional opportunities to improve the efficiency of TE materials. Aerogels are one type of nano-material that offers opportunities to increase the efficiency of TE materials by controlling particle size, particle composition and by reducing the thermal conductivity. Bismuth telluride (Bi2Te3) is the most studied TE material and our objective was to produce bismuth telluride aerogels with controlled microstructures and thermal conductivities to increase the TE figure of merit. Aspen Aerogels developed a novel synthesis method to prepare Bi2Te3 aerogels using the principles of colloidal chemistry and sol-gel chemistry. The reaction conditions were investigated and optimized so that gels could be obtained at low reaction temperatures. The gels were aged and dried using supercritical CO2. The aerogels were characterized by BET, XRD, and SEM. The best aerogels were hot pressed and Seebeck coefficients were determined. The synthetic approach developed and the properties of the aerogels will be presented and compared with Bi2Te3 aerogels and materials prepared by other methods. INTRODUCTION Refrigeration, air conditioning, and other cooling requirements in buildings, industry, and transportation sectors account for about 10 quads of U.S. primary energy consumption [1]. Significant improvement of current technologies is required for space cooling in buildings and vehicles – as well as for refrigeration in residential, commercial, and industrial applications – that are more energy efficient, avoid net direct greenhouse gas emissions, reduce lifecycle costs, and can impact large markets. The efficiency of thermoelectric (TE) devices has remained frustratingly low until recently. However, new results suggest that as the length scale decreases so that the number of atoms in any direction (x, y, or z) becomes less than ca. 102, quantumconfinement effects arise which allows
Data Loading...
