HZB presents research on thermoelectrics
HZB Group at the ICT/ECT2015. From left to right: Dr. Klaus Habicht (Head of the Department for Methods for Characterization of Transport Phenomena in Energy Materials), Dr. Tommy Hofmann, Dr. Katharina Fritsch, Dr. Britta Willenberg, Dr. Katrin Meier-Kirchner
The annual "International Conference on Thermoelectrics (ICT)” and the "European Conference on Thermoelectrics (ECT)” took place together from 29 June to 02 July 2015 in Dresden, Germany. For the first time, HZB participated in this international multidisciplinary meeting. The HZB Department "Methods for Characterization of Transport Phenomena in Energy Materials" headed by Dr. Klaus Habicht presented their research in two talks and one poster.
Dr. Tommy Hofmann presented a talk on the thermoelectric properties of nanostructured silicon which is prepared at HZB by an electrochemical etching process and which is characterized in-house by macroscopic techniques, and by microscopic probes. This material is currently of great interest as silicon is earth-abundant, non-toxic and inexpensive, which distinguishes it from current thermoelectric materials such as Bi2Te3 or PbTe. The nanostructuring of this simple material offers new possibilities to increase the thermoelectric efficiency of the material, for example by reducing the thermal conductivity through the artificial creation of interfaces within the material. The thermal conductivity as macroscopic quantity relates to the transport of lattice vibrations or phonons on the microscopic level, which can be ideally studied using inelastic neutron scattering techniques available at HZB's research reactor BER II.
In the second talk, Dr. Katharina Fritsch gave an overview of the experimental methods for thermoelectrics research applied in the Department, and she presented selected ongoing research projects. Discussed projects ranged from nanostructured silicon to experiments on the lattice dynamics and electronic bandstructure of low-dimensional thermoelectric single crystals as well as structural investigations of skutterudite compounds.
The structure-functionality relationship in skutterudite compounds were also the topic of the poster entitled "Yb-filled skutterudites: a combined macroscopic and microscopic approach", in which Dr. Britta Willenberg presented results of a project realised as cooperation between the Department and the Institute of Materials Research at the German Aerospace Center (DLR) in Cologne.
The meeting was a perfect venue to get feedback on our research projects and to present the experimental facilities and research opportunities at HZB to a large audience from Germany and abroad. Overall, we we were able to attract new potential collaboration partners.
- A new way to control the magnetic properties of rare earth elementsThe special properties of rare earth magnetic materials are due to the electrons in the 4f shell. Until now, the magnetic properties of 4f electrons were considered almost impossible to control. Now, a team from HZB, Freie Universität Berlin and other institutions has shown for the first time that laser pulses can influence 4f electrons- and thus change their magnetic properties. The discovery, which was made through experiments at EuXFEL and FLASH, opens up a new way to data storage with rare earth elements.
- BESSY II shows how solid-state batteries degradeSolid-state batteries have several advantages: they can store more energy and are safer than batteries with liquid electrolytes. However, they do not last as long and their capacity decreases with each charge cycle. But it doesn't have to stay that way: Researchers are already on the trail of the causes. In the journal ACS Energy Letters, a team from HZB and Justus-Liebig-Universität, Giessen, presents a new method for precisely monitoring electrochemical reactions during the operation of a solid-state battery using photoelectron spectroscopy at BESSY II. The results help to improve battery materials and design.
- From waste to value: The right electrolytes can enhance glycerol oxidationWhen biomass is converted into biodiesel, huge amounts of glycerol are produced as a by-product. So far, however, this by-product has been little utilised, even though it could be processed into more valuable chemicals through oxidation in photoelectrochemical reactors. The reason for this: low efficiency and selectivity. A team led by Dr Marco Favaro from the Institute for Solar Fuels at HZB has now investigated the influence of electrolytes on the efficiency of the glycerol oxidation reaction. The results can help to develop more efficient and environmentally friendly production processes.