Charting lattice thermal conductivity for inorganic crystals and discovering rare earth chalcogenides for thermoelectrics

Thermoelectric power generation represents a promising approach to utilize waste heat. The most effective thermoelectric materials exhibit low thermal conductivity κ. However, less than 5% out of about 105 synthesized inorganic materials are documented with their κ values, while for the remaining 95% κ values are missing and challenging to predict. In this work, by combining graph neural networks and random forest approaches, we predict the thermal conductivity of all known inorganic materials in the Inorganic Crystal Structure Database, and chart the structural chemistry of κ into extended van-Arkel triangles. Together with the newly developed κ map and our theoretical tool, we identify rare-earth chalcogenides as promising candidates, of which we measured ZT exceeding 1.0. We note that the κ chart can be further explored, and our computational and analytical tools are applicable generally for materials informatics

Harnessing non-stoichiometry and disorder in thermoelectric materials

Thermoelectric materials require an exquisite balancing of thermal and electronic transport properties. Core to achieving such a balance in thermoelectric materials is the pursuit of non-stoichiometric compositions. Non-stoichiometry serves to control the charge carrier concentration, alter the electronic structure, control electron and phonon scattering, and produce anomalies in the phononic structure. As such, the optimized material is far removed from the original parent compound. Looking to the future, a deeper understanding of non-stoichiometry and its impact on electronic and phononic transport is critical to designing the next generation of thermoelectric materials. To convey the importance of non-stoichiometry in thermoelectric materials, we will begin with two classic case examples that highlight how non-stoichiometry profoundly alters transport in thermoelectric materials. These include (i) the alteration of the electronic structure through resonant states in PbTe and (ii) alteration to phonon transport via ‘rattling’ modes in skutterudite compounds. With this foundation, we discuss our recent efforts to control transport in pnictide and chalcogenide compounds through a combination of first principles calculations of defect structures, combinatorial growth of alloys, and bulk synthesis. For example, Figure 1 highlights how first principles calculations can offer insight into native defect populations and their impact on electronic structure. Strategies to accelerate discovery in this high dimensional phase space and critical challenges that remain serve to conclude this discussion of thermoelectric materials. Please click Additional Files below to see the full abstract

Airway management in cardiac arrest -- not a question of choice but of quality?

This study presented an innovative method in order to estimate training required for skilful and successful intubations during ED cardiac arrests. Video reviews were taken from a system that routinely records ED staff during cardiac arrests and as these recordings are already part of everyday clinical practice, it is likely that there is minimal Hawthorne effect. Cardiac arrest research often reiterates the fact that the basics should be done well. It is commendable that intubations by the residents in this observational study resulted in a modest mean delay in chest compressions of only 8.6 seconds for the intubation attempt. However, nearly a third of intubation attempts were unsuccessful at the first attempt, and there were 11 oesophageal intubations (albeit they were all recognised) in the 93 patients that were included