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Early transition metal dopants in cuprous oxide: To spin or not to spin
손알로이시우스,Joel Wallman,Bernard Delley,Catherine Stampfl 한국물리학회 2013 Current Applied Physics Vol.13 No.8
We present a trend study of a large variety of dopants at the cation site in Cu2O (i.e. substituting Cu),focussing largely on the early 3d-, 4d-, and 5d-transition metals (TMs) in which many of them are known to be non-magnetic. We also include s-, sp- and d10-metals for comparison. We find that doping with spelements results in zero spin moment while dopants with a partially filled d-band show a stronger tendency to magnetize and 3d-TM dopants exhibit a larger magnetic moment than most of the 4d- and 5d-TM dopants. From this trend study, we also find a correlation between their substitution enthalpy and associated interatomic relaxations. In particular, Ti-doped Cu2O appears to be an interesting system,given its “peculiar” ability to exhibit a spin moment when doped with a non-magnetic substituent like Ti. We also find that the interaction between two doped Ti atoms in Ti2:Cu2O is predominantly antiferromagnetic,and interestingly (and unexpectedly), this interaction rapidly declines as a function of interdopant distance, as in the case for the magnetic late-TM dopants like Co2:Cu2O.
Yoo, Su-Hyun,Lee, Ji-Hwan,Delley, Bernard,Soon, Aloysius The Royal Society of Chemistry 2014 Physical chemistry chemical physics Vol.16 No.34
<P>A first-principles description and prediction of brominated nanocrystals of Pd is presented. In particular, we conducted an extensive study of the adsorption behaviour of Br on various Pd surfaces (including both low and high Miller-index surfaces) as a function of its surface coverage. By coupling our calculated surface energies with <I>ab initio</I> (electrochemical) thermodynamics and the Gibbs–Wulff shape model, we find that the relative stability of the Pd surfaces is strongly modified by Br, allowing high Miller-index surfaces of Pd (namely the (210) surface) to become competitively favourable at moderate concentrations of Br. We also show that Pd nanoparticles assume a cube-like crystal shape at high concentrations of Br, exposing mainly the (100) facets with a Br surface coverage of 0.5 ML. This not only confirms and explains recent solution synthesis results, but also provides a quantitative atomic picture of the exposed surface facets, which is crucial in understanding the local surface chemistry of shape-controlled nanoparticles for better nanocatalyst design.</P> <P>Graphic Abstract</P><P>We study the chemisorption of Br on the low and high Miller-index surfaces of Pd nanoparticles, and provide a quantitative atomic picture and physics of these brominated palladium for the systematic design of more selective and active Pd shape-sculptured nanocatalysts. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4cp02384f'> </P>