Paul Scherrer Institute

About: Paul Scherrer Institute is a facility organization based out in Villigen, Switzerland. It is known for research contribution in the topics: Neutron & Large Hadron Collider. The organization has 9248 authors who have published 23984 publications receiving 890129 citations. The organization is also known as: PSI.

Computing the mobility of grain boundaries.

Abstract: As current experimental and simulation methods cannot determine the mobility of flat boundaries across the large misorientation phase space, we have developed a computational method for imposing an artificial driving force on boundaries. In a molecular dynamics simulation, this allows us to go beyond the inherent timescale restrictions of the technique and induce non-negligible motion in flat boundaries of arbitrary misorientation. For different series of symmetric boundaries, we find both expected and unexpected results. In general, mobility increases as the grain boundary plane deviates from (111), but high-coincidence and low-angle boundaries represent special cases. These results agree with and enrich experimental observations.

Competition between the pseudogap and superconductivity in the high- T c copper oxides

Abstract: In a classical Bardeen-Cooper-Schrieffer superconductor, pairing and coherence of electrons are established simultaneously below the critical transition temperature (T(c)), giving rise to a gap in the electronic energy spectrum In the high-T(c) copper oxide superconductors, however, a pseudogap extends above T(c) The relationship between the pseudogap and superconductivity is one of the central issues in this field Spectral gaps arising from pairing precursors are qualitatively similar to those caused by competing electronic states, rendering a standard approach to their analysis inconclusive The issue can be settled, however, by studying the correlation between the weights associated with the pseudogap and superconductivity spectral features Here we report a study of two spectral weights using angle-resolved photoemission spectroscopy The weight of the superconducting coherent peak increases away from the node following the trend of the superconducting gap, but starts to decrease in the antinodal region This striking non-monotonicity reveals the presence of a competing state We demonstrate a direct correlation, for different values of momenta and doping, between the loss in the low-energy spectral weight arising from the opening of the pseudogap and a decrease in the spectral weight associated with superconductivity We therefore conclude that the pseudogap competes with the superconductivity by depleting the spectral weight available for pairing

Atomic-scale engineering of indium oxide promotion by palladium for methanol production via CO 2 hydrogenation

Abstract: Metal promotion is broadly applied to enhance the performance of heterogeneous catalysts to fulfill industrial requirements. Still, generating and quantifying the effect of the promoter speciation that exclusively introduces desired properties and ensures proximity to or accommodation within the active site and durability upon reaction is very challenging. Recently, In2O3 was discovered as a highly selective and stable catalyst for green methanol production from CO2. Activity boosting by promotion with palladium, an efficient H2-splitter, was partially successful since palladium nanoparticles mediate the parasitic reverse water–gas shift reaction, reducing selectivity, and sinter or alloy with indium, limiting metal utilization and robustness. Here, we show that the precise palladium atoms architecture reached by controlled co-precipitation eliminates these limitations. Palladium atoms replacing indium atoms in the active In3O5 ensemble attract additional palladium atoms deposited onto the surface forming low-nuclearity clusters, which foster H2 activation and remain unaltered, enabling record productivities for 500 h. Generating and quantifying the effect of the promoter speciation in heterogeneous catalysts is very challenging. Here, the authors show that the precise palladium atoms architecture reached by controlled co-precipitation overcomes selectivity and stability limitations associated with palladium nanoparticles for CO2-based methanol synthesis.