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The low and weakly temperature-varying lattice thermal conductivity, κL (T), in crystals with a complex unit cell such as type-I clathrates is assumed to originate from a reduced momentum and energy space available for propagative lattice vibrations, which is caused by the occurrence of low-energy optical phonon modes. In the context of ab initio self-consistent phonon (SCP) theory, it has been shown that the cubic and quartic anharmonic interactions result in a temperature-induced energy renormalization of these low-lying optical branches which contributes to the anomalous behavior of κL (T) in structurally ordered type-I clathrates [T. Tadano and S. Tsuneyuki, Phys. Rev. Lett. 120, 105901 (2018)]. By means of inelastic neutron scattering, we provide evidence for this energy renormalization in temperature, which has been resolved for transversely and longitudinally polarized phonons in the single crystal type-I clathrate Ba7.81Ge40.67Au5.33. By mapping the neutron intensity in the momentum space, we demonstrate the coherent character of the low-lying optical phonons. The overall phonon spectrum and dynamical structure factors are satisfactorily reproduced by ab initio harmonic calculations using density functional theory with the meta-GGA SCAN functional and a fully ordered structure. However, a polarization-dependent cutoff energy with opposing temperature shifts for longitudinal and transverse acoustic dispersions is experimentally observed which is not reproduced by the simulations. Anharmonicity affects the energies of the low-lying optical phonons in the transverse polarization, which compares quantitatively well with available results from SCP theory, whereas differences are observed for the longitudinal polarization

Electrocatalytic reduction of CO2 reduction reaction(CO2RR) to high energy density fuel and high value-added carbon products under mild conditions is an extremely promising way for reduction of the CO2 concentration in atmosphere and storage of the intermittent renewable energy, as well as for carbon neutralization. The design and development of low-cost high-performance catalysts with high activity, high selectivity, high stability and significant suppress of hydrogen evolution reaction(HER) is the key to the CO2RR research. On the other hand, single atomic catalysts (SACs), due to their unique electronic and geometric structures, exhibit unusual catalytic activity for many important chemical reactions, such as CO oxidation, hydrogenation, OER, ORR, HER, etc., and have attracted extensive attention. Inspired by the profound progress, very recently, N-doped porous carbon support transition metal single atomic materials(M-N-C) have been employed in CO2RR research. The results manifest that M-N-C catalytic materials have exciting prospects for CO2RR, and are expected to be a substitute for precious metal(Au, Ag) catalysts for CO2 reduction in electrolyte aqueous media. This review is focused on fabrications, electrocatalytic performance and MNx active sites of M-N-C SACs used in electrochemical CO2RR. Finally, the problems remaining to be solved are summarized, and future research aspects and new ideas are prospected.

SSCI-VIDE+ECI2D+LPI; International audience; Intermetallic compounds exhibit a high degree of structural diversity, with numerousunique structure types. Among them, complex intermetallic compounds, also known ascomplex metallic alloys (CMAs), present large periodic structures based on building blocksconsisting in highly symmetric atomic polyhedra, often displaying motifs of simplercompounds, like hierarchical replacement of atomic positions in the more elementalstructures by larger atomic clusters or cages in the complex ones. Typical clusters/cagesfound in quasicrystals include Mackay, Bergman and Tsai clusters, and a large variety ofhighly symmetric polyhedra are generally found in CMAs.The structural complexity of CMAs extends to the surface. In this talk, the relationshipbetween the three dimensional cluster-based bulk structure and the two-dimensional surfacewill be questioned in two cases: the pseudo-10fold surfaces of Al13TM4 (TM = Fe, Co)quasicrystalline approximants [1] and the low-index surfaces of the Ba8Au5.25Ge40.75 cagecompounds [2], using a combination of experimental techniques under ultra-high vacuumand theoretical calculations based on the Density Functional Theory. The focus will be onthe different mechanisms by which stable surface terminations are selected, to highlight thefactors governing the atomic and electronic properties of the observed surface.The specific atomic arrangements at the surface induced by the intrinsic cluster-based bulkstructure of CMAs are expected to affect their surface properties. This will be discussed inthe case of the pseudo-10fold surfaces of Al13TM4 compounds, in terms of their catalyticproperties [3].[1] Ph. Scheid et al., Acta Cryst. A, 75 (2019) 314-324; É. Gaudry et al., Phys. Rev. B 94 (2016) 165406; J. Ledieu et al., Phys. Rev. Lett. 110 (2013) 076102.[2] K. Anand et al., J. Phys. Chem.. C 122 (2018) 2215 and 29298.[3] L. Piccolo et al., Sci. Technol. Adv. Mater. 20 (2019) 557.

The Ba - containing type - I clathrates show promising thermoelectric (TE) properties [1]. Therefore, Ba - Au - Ge type - I clathrates are thus of interest for TE applications as well [2]. Both p - and n - type conductivity were found in the Ba - Au - Ge system, depending on Au content. Here we present the measurements of the electrical and thermal transport on the p - type single crystal Ba 8 Au 5.25 Ge 40.3 □ 0.45 along [001], [110] and [111] directions. The sample shows a semiconducting - like behavior. The Hall coefficient R H exhi bits a positive sign, pointing on the dominance of electron - like conduction. The Hall mobility μ H below ~ 100 K follows approximately T - 3/2 law, while above 100 K the μ H is temperature independent, which denotes on neutral - impurity scattering. Thermal conductivity κ , measured by steady state method and 3ω method, is rather low with κ ~ 1 Wm - 1 K - 1 at room temperature. It is interesting to point out that the electrical resis tivity, R H and κ along [110] direction revealed a different magnitude compared to [001] and [111] directions. It seem reasonable to assume that this observation is due to different electron - phonon coupling for different directions, as it will be shown by l ow - temperature κ data. [1] A. Saramat, G. Svensson, A. Palmqvist, C. Stiewe, E. Mueller, D. Platzek, S. Williams, D. Rowe, J. Bryan, and G. Stucky, J. Appl. Phys. 99 , 023708 (2006). [2] H. Zhang, H. Borrmann, N. Oeschler, C. Candolfi, W. Schnelle, M. Schmidt, U. Burkhardt, M. Baitinger, J. - T. Zhao, Y. Grin, Inorg. Chem. 50 , 1250 (1250). We acknowledge financial support from the Austrian Science Fund (FWF project TRP 176 - N22) and from the German Research Foundation (DFG project SPP 1386 - nanOcla)

International audience; Polycrystalline samples of the type-I clathrate Ba8NixGe46−x−y□y were synthesized for 0.2 ⩽ x ⩽ 3.5 by melt quenching and for 3.5 < x ⩽ 6.0 by melting with subsequent annealing at 700 °C. The maximum Ni content in the clathrate framework at this temperature was found to be x ≈ 4.2 atoms per unit cell. Thermoelectric and thermodynamic properties of the type-I clathrate were investigated from 300 to 700 K by means of electrical resistivity, thermopower, thermal conductivity and specific heat measurements. As the Ni content increases, the electronic properties gradually evolve from a metallic character (x

For the design of load carrying glazing structures the connection technique plays an important role, as e.g. there are significant stress concentrations in the vicinity of holes that are subject to a point-like support of glass panes. If no further constructional means are provided, the stress peaks cannot be redistributed and thus a sudden brittle failure is likely to occur. In particular this concerns bolts in bearings of drilled glass holes as long as no ductile stress distributing interlayers in the clearance between hole bearing and bolt shank is provided. In the article, a simple design formula for glass joints with bolts in bearings is suggested that is based on an analytical approach where the local stress distributions coming on the one hand from the bearing pressure and on the other hand from the net section stress concentrations are superposed, and both for which the solutions according to AIRY’s differential equation are found resp. used further on. By this the relevant stresses in dependence on the acting design force, the hole diameter and the pane thickness can be determined without performing complex and time consuming Finite Element calculations., Challenging Glass Conference Proceedings, Vol. 2 (2010): Challenging Glass 2

To realize architectural attractive transparent and lightweight constructions bonded hybrid steel-glass beams have been developed, where flanges of steel and webs of glass are assembled to I-shaped profiles using adhesives. The load-bearing capacity of such beams is governed – apart from the mechanical and strength characteristics of the adherent - by ageing, temperature and creeping. By means of small scale push-out-tests the properties of different adhesive geometries, the influence of the manufacturing process and the general load carrying behaviour of bonded hybrid steel-glass-beams are shown., Challenging Glass Conference Proceedings, Vol. 2 (2010): Challenging Glass 2