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Abstract: Energy dispersive extended X-ray absorption fine structure spectroscopy (ED-XAFS), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and mass spectrometry (MS), have been combined for the structure–function study of Rh and RhPd supported catalysts for the reduction of NO by CO. The combined results show that although alloying of Rh with Pd prevents the dissociative oxidation of the Rh by NO, it does not prevent the extensive disruptive oxidation of Rh by CO. The influence of oxidative disruption by molecular CO in such systems may therefore be far more pervasive and catalytically important than has been previously observed. The overall metal particle size observed in the RhPd alloy system during the CO/NO reaction is significantly larger than for the Rh-only system for the entire temperature range employed. The catalytically active sites, however, are likely to be similar, with the overall activity of the alloy system to be reduced due to inactive RhPd alloy nanoparticles.

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Abstract: We studied the plastic deformation of a Cu monochromator loaded in tension along the [I 10] direction between 0 and 4% equivalent shear strain. We tracked the changes in the orientation and mosaicity of the specimen at several locations simultaneously by analysing the neutron spectra transmitted by the sample. We found that an initial misalignment between different regions of the specimen decreases as deformation proceeds, to reach a minimum at 2% shear strain. On the other hand, the mosaicity of most reflections changes linearly from 10 to 30 min, except for the [2 0 0] reflection, which presents a more complex behaviour.The experiments used a novel transmission technique involving a polychromatic neutron beam and a pixellated time of flight detector. The technique exploits sharp dips in intensity present in the transmitted neutron spectrum, corresponding to the neutrons removed from the beam after being diffracted by the crystal planes.

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Abstract: High-resolution x-ray and neutron powder-diffraction measurements were performed on polycrystalline VOMoO4. Below similar or equal to 40 K the system orders in a simple Neel antiferromagnetic state (propagation vector k=0), indicating a dominant role of the nearest-neighbor interactions. The order is three dimensional but the reduced saturated magnetic moment m of 0.41 (1) mu(B)/V4+ at 2 K indicates strongly two-dimensional character and enhanced quantum fluctuations. On cooling, there is no evidence of a reduction of the crystal symmetry. However, neutron diffraction indicates an anomalous evolution of the lattice parameters, which can be related to the onset of magnetic correlations.