August 1, 2012.
The impact of neutron irradiation on the thermoelectric (TE) properties of n‐type La 3‐x Te 4 , p‐type Yb 14 MnSb 11 , and n‐ and p‐type filled skutterudites is reported and discussed. During operation in Radioisotope Thermoelectric Generators (RTGs), these TE materials are expected to experience a certain degree of radiation over time, specifically, fission neutrons. This could affect their TE properties and thus the performance of the generators over time. In this study three samples of each of the above materials were exposed to 18 years worth of neutron radiation near room temperature at the Ohio State University Research Reactor (OSURR). Their electrical resistivity, carrier mobility, carrier concentration, thermal conductivity, Hall coefficient, and Seebeck coefficient were measured before and after radiation exposure at room temperature. Post‐irradiation the properties are measured twice. The first measurements were conducted on the samples as received after irradiation. The samples were then polished to remove any surface discoloration or oxidation films. The above properties were tested again to determine if the initial surface characteristics played an influence on the TE properties. The room temperature TE properties indicate that the neutron exposure had limited impact on the Seebeck and resistivity (less than 10% deviation). Results agree with previous investigations that established the minimal impact of neutron exposure on other similar TE materials. High‐temperature TE property measurements, including thermal conductivity, will also be performed on the samples to confirm the initial room temperature results.
NASA Jet Propulsion Laboratory (JPL)
This material is based upon work supported by the S.D. Bechtel, Jr. Foundation and by the National Science Foundation under Grant No. 0952013 and Grant No. 0833353. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the S.D. Bechtel, Jr. Foundation or the National Science Foundation. This project has also been made possible with support of the National Marine Sanctuary Foundation. The STAR program is administered by the Cal Poly Center for Excellence in Science and Mathematics Education (CESaME) on behalf of the California State University (CSU).