The annex aims to develop test methods for the evaluation of thermoelectric materials and to develop precision statements for the standardization of these methods. Specifically, we aim to:
- Exchange Technical information
- Develop standard testing methods and procedures for thermoelectrics (bulk and nano-composite materials)
- Conduct international round-robin study on thermoelectric materials (20-500ºC)
- Characterize key properties (transport properties and others using advanced tools such as STEM and neutron scattering) of potential thermoelectrics for transportation applications
Participating lead labs
USA Oak Ridge National Laboratory, Oak Ridge Tennessee
Canada CANMET Materials
China Shanghai Institute of Ceramics, CAS
Germany Fraunhofer Institute for Physical Measurement
Annex VIII is addressing one of the most important issues facing the thermoelectric community: reliability of transport data. The round-robin results showed significant problems in two of the four measurements that determine the figure of merit (ZT). The test procedures developed by Annex VIII is critical to the transition from laboratory materials development to module and device production. It has significant impact on the commercialization and scale-up and manufacturing of thermoelectric devices.
First international Round-robin study
The first round-robin on bismuth telluride was conducted in 2010 all the participating labs completed testing two sets of specimens (n-type and p-type). The results showed significant problem in thermal conductivity measurements (thermal diffusivity and specific heat). The largest measurement error came from heat capacity measurements. The Annex round-robin results were well received by the thermoelectric community. It was considered a timely and very important contribution.
Second international Round-robin study:
After the discussion on the first round-robin results, the second round-robin testing began in August of 2010 and was completed by August 2011. Two sets of p-type materials were measured at 7 labs in 4 countries. The results of round-robin 1 were given to all the labs as reference. The issues identified in round-robin 1 were discussed by participating labs. The same test instruments used for round-robin 1 were used for all the transport properties in round-robin two. All the labs completed tests on all specimens. In some cases, thermal and electrical properties testing were carried out at different labs within the same country.
Dr. Hsin Wang
Senior R&D Staff
Oak Ridge National Laboratory
Oak Ridge, TN 37831