Creep of Thermoelectric Materials

Muath Mohammed Al Malki

Studies show that more than 60% of energy is dissipated as waste heat, which should be collected in a way or another and converted to useful energy. Thermoelectric Materials (TE) does this job of converting heat into electricity via the well-known “Seebeck effect”. One of the traditional applications of TE in power generation is the use of radioisotopes thermoelectric generators in space probes and satellites (RTGs).

Stresses due to the temperature gradient between the hot and cold legs can deteriorate the mechanical performance of TE. Other stresses, such as vibration and clamping stresses, may contribute as well. As a major concern, creep can lower the mechanical lifetime of the installed TE. Furthermore, the thermoelectric performance, represented by the figure of merit ZT, was shown to drop down by 20-30% due to the increase of the dislocation density and the elimination of the high-angle grain boundaries; a result of creep. In this research, we are exploring further the relation between the mechanical degradation and the deterioration in the thermoelectric performance for different thermoelectric classes ( TAGS, HH..)

Strain rate against 1/T plot of TAGS-85, PbTe, and Bi2Te3, showing best-fit creep activation energies for PbTe and TAGS-85. [4]

ZT values of TAGS-85. After creep 1(Red): sample creeped under 2.6 MPa to 26.5 MPa stress at 400°C. After creep 2 (Blue): sample creeped under 5.1 MPa at 375, 400, 425°C, compared to the un-creeped sample (Green) [4]

Related Publications

  1. Guan, Z. P., & Dunand, D. C. (2013). Compressive creep behavior of cast Bi2Te3. Materials Science and Engineering: A, 565, 321-325.
  2. Li, C. C., Snyder, G. J., & Dunand, D. C. (2017). Compressive creep behaviour of hot-pressed PbTe. Scripta Materialia, 134, 71-74.
  3. Michi, R. A., Kim, G., Kim, B., Lee, W., & Dunand, D. C. Compressive Creep Behavior of Hot-Pressed Mg1.96 Al0.04Si0.97 Bi0.0. Scripta Materialia. [In print]
  4. Chang, M., Agne, M. T., Michi, R. A., Dunand, D. C., & Snyder, G. Compressive Creep Behavior of hot-pressed TAGS-85. [ Under Review]