Synthesis and Thermoelectric Properties of Ce y Ru x Ir 4-x Sb 12 Filled Skutterudite Compounds
- PDF / 136,303 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 94 Downloads / 241 Views
0886-F09-10.1
Synthesis and Thermoelectric Properties of CeyRuxIr4-xSb12 Filled Skutterudite Compounds April D. Jewell, Jong-Ah Paik and Thierry Caillat Jet Propulsion Laboratory/California Institute of Technology Pasadena, CA 91109 ABSTRACT Radioisotope Thermoelectric Generators (RTGs) have proved to be reliable, long-lived sources of electrical power that have enabled the conduct of a number of important NASA deep space missions since 1961. Past RTGs have used two types of thermoelectric materials: PbTe/TAGS and SiGe. In an effort to further improve both the thermoelectric efficiency and specific power of the next generation of RTGs, JPL is investigating a number of potential highefficiency, high-temperature thermoelectric materials that could operate at a hot-side temperature of up to 1275 K. Among the materials being studied are the refractory CeyRu4-xIrxSb12 filled skutterudite compounds. We have synthesized polycrystalline samples for x ≤ 1.5 by a powder metallurgy technique. Dense samples have been hot-pressed from the pre-reacted powders and characterized by a variety of techniques including electron probe microanalysis, differential thermal analysis and thermogravimetic analysis. Seebeck coefficient, electrical resistivity, Hall coefficient, and thermal conductivity measurements have been conducted on the samples from room temperature to 1275 K. Results show that the samples are phase stable up to 1275 K. The results of the transport property measurements are presented and discussed. INTRODUCTION Skutterudite based unicouples have been under development at the Jet Propulsion Laboratory (JPL) since 1997 [1-5]. Development efforts to date have primarily focused on unicouples based on skutterudite compounds capable of operating at a maximum hot-side temperature of 975 K: p-CeFe3Ru1Sb12 and n-CoSb3. Unicouples based on these compounds have been developed and tested at JPL and efficiency up to 14 % for a 975 K-300 K operation has been demonstrated. Some of this first generation skutterudite unicouples are shown in Figure 1. While the efficiencies demonstrated to date make this first generation of unicouples interesting for potential integration into advanced RTGs, the PuO2 heat source used in the RTGs is designed to operate at temperature greater than 975 K (up to ~1275 K) and SiGe–based RTGs have used SiGe unicouples operating at a hot-junction temperature of 1275 K. There is therefore an interest for developing efficient thermoelectric materials capable of operating up to 1275 K. They could be segmented to the 975 K skutterudite compounds developed to date to potentially take full advantage of the 1275 K hot-junction temperature provided by the PuO2 heat source and further increase conversion efficiencies. A number of high-temperature thermoelectric materials potentially capable of operating at temperatures up 1275 K are under investigation at JPL. They include high-temperature skutterudite materials such as p-type CeyRu4-xIrxSb12 filled compounds. This paper describes the synthesis and characterization of so
Data Loading...
