Scientific Events

Half-Heusler compounds exhibit significant potential in thermoelectric applications for power generation up to 1000 K, notwithstanding the substantial challenges posed by the cost of constituent elements and the imperative to augment the average thermoelectric figure-of-merit (zT_ave) for more practical applications. Overcoming these obstacles demands the advancement of high-performance p-type TaFeSb thermoelectric materials with diminished Ta content. This investigation systematically explores the quaternary-phase space encompassing Ta, Nb, V, and Ti to ascertain an optimal composition, namely Ta_0.42Nb_0.3V_0.15Ti_0.13FeSb. This composition is characterized by a remarkable reduction in Ta concentration coupled with an enhancement in zT, peaking at 1.23 at 973 K. Moreover, the integration of a high-mobility secondary phase, InSb, fosters enhancements in both the Seebeck coefficient and electrical conductivity, resulting in a 23% augmentation in the average power factor, while concurrently suppressing lattice thermal conductivity. The optimized composite, Ta_0.42Nb_0.3V_0.15Ti_0.13FeSb-(InSb)_0.015, achieves a peak zT value of 1.43 at 973 K and a zT_ave of 1 from 300 K to 973 K, thereby setting a precedent among p-type half-Heusler materials. Additionally, a single-leg device demonstrates a peak efficiency of approximately 8% under a temperature difference of 823 K vs. 303 K. These findings underscore the substantial potential of the proposed material design and fabrication methodologies in fostering efficient and sustainable thermoelectric applications. [more]

Are you a Master's student who wants to explore the prospect of doing a PhD in Germany? Join us for a unique webinar event designed to give you an insight into the benefits of doing a PhD at the prestigious Max Planck Society as part of an International Max Planck Research School (IMPRS) in North Rhine-Westphalia (NRW), Germany. [more]

The energy transition requires the introduction of sustainable energy sources. Hydrogen is one of these options, but its efficient and sustainable production from water splitting as well as its storage is still a challenge. In order to understand the structure-property at different length scales, it is essential to combine complementary in situ/operando techniques with ex situ analysis. [more]

High entropy materials are materials with 5 or more principle components within crystalline lattices. High entropy metal chalcogenides are a recent (since 2016) development in this area that have shown exceptional promise in both thermoelectric energy conversion and electrocatalysis. However, these materials remain limited in both compositional range and characterisation. In this talk the compositional boundaries of high entropy metal sulfides will be explored, along with advanced and comprehensive characterisation techniques and our initial explorations into acidic hydrogen evolution electrocatalysis. [more]

Only 12% of plastic waste is recycled, mainly because the predominantly applied technique of melting and re-extrusion produces a lower quality material [1]. Alternatively, chemical depolymerization can produce monomers to make high-quality plastics again. [more]

The increasing demand on lightweight structures requires high-strength materials. However, with increasing strength many materials show an increasing susceptibility to hydrogen embrittlement. Hence, it is of vital interest to understand the mechanisms of hydrogen embrittlement. [more]

Thermoelectric materials can realize waste heat recovery and solid-state refrigeration, providing sustainable solutions to the energy crisis and environmental pollution. The performance of thermoelectric materials is gauged by the transport of electrons and phonons. Materials with fast electron movement but slow phonon propagation would be ideal thermoelectrics. These transport behaviors of carriers are influenced by the intrinsic chemical bonding mechanism and structural defects of materials. Understanding the bonding and microstructures of materials is of paramount importance to improve their thermoelectric properties. Atom probe tomography (APT) provides a unique combination of characterizing chemical bonding and lattice defects, being a very powerful tool in the study of thermoelectric materials. It has been revealed that many of the high-performance thermoelectric chalcogenides utilize metavalent bonding (MVB), which can be distinguished from other bonding mechanisms by the unconventionally high value (>60%) of “probability of multiple events (PME)” measured by APT. Thus, many new compounds with high thermoelectric performance can be designed by tailoring their chemical bonds, and APT is an indispensable technique to corroborate the bonding transition. Owing to the high spatial and chemical resolution of APT, the local change of chemical bonding at defects such as grain boundaries and precipitates can also be detected by APT. This enables us to better understand the role of chemical bonding in regulating the electron and phonon transport across individual defects. The results in turn provide insights into the tailoring of thermoelectric properties by manipulating the local chemical bonds. For example, the thermoelectric properties of polycrystalline SnSe have been significantly improved by removing the stiff Sn-O bonds at the grain boundary as directly observed by APT. In contrast, the strong bonding connection between thermoelectric and interfacial materials enables a high-efficiency and durable thermoelectric device. Based on APT, in conjunction with other characterization techniques, we can explore some uncharted territories in the design of thermoelectric materials. [more]