Disentangling coordination and alloy effects in transition metal nanoalloys from their electronic structure

International audienc

Disentangling coordination and alloy effects in transition metal nanoalloys from their electronic structure

International audienc

Disentangling coordination and alloy effects in transition-metal nanoalloys from their electronic structure

International audienc

Electronic structure of CoPt based systems : from bulk to nanoalloys

An accurate description of the local electronic structure is necessary for guiding the design of materials with targeted properties in a controlled way. For complex materials like nanoalloys, self-consistent tight-binding calculations should be a good alternative to ab initio methods, for handling the most complex and large systems (hundreds to thousands of atoms), provided that these parameterized method is well founded from ab initio ones that they intend to replace. Ab initio calculations (density functional theory) enabled us to derive rules for charge distribution as a function of structural change and alloying effects in Co and Pt based systems, from bulk to nanoalloys. A general local neutrality rule per site, orbital and species was found. Based on it, self-consistent tight-binding calculations could be implemented and applied to CoPt nanoalloys. A very good agreement is obtained between tight-binding and DFT calculations in terms of local electronic structure

Effect of the chemical order on the electrocatalytic activity of model PtCo electrodes in the oxygen reduction reaction

PtCo alloys have long been known to possess higher activity in the electrochemical oxygen reduction reaction compared to pure Pt. This work addresses the influence of the chemical order on the electrocatalytic activity of PtCo alloy, the phenomenon, which has been already documented in the literature but yet poorly understood. Single crystalline PtCo(0 01) alloy films were epitaxially grown on Mg(0 0 1) substrates and used as model electrodes to study the influence of the chemical order on the electrochemical oxygen reduction reaction. Electrodes with close Pt:Co atomic ratios in the bulk and near surface region show grossly different electrocatalytic activities against the chemical order, the ordered L1(0) phase being ca. 7 times more active than the disordered fcc A1 structure. Electronic structure calculations and quantum mechanical theory of electron transfer are utilized to provide a rational for this remarkable phenomenon. (C) 2013 Elsevier Ltd. All rights reserved

Gas scintillation chamber for superheavy elements detection at GANIL

In the paper we present scintillation-ionization detector (SID) — a new device for support of the superheavy elements (SHE) identification in the standard, complete fusion methods. We highlight problems with background effects in SHE production and their minimization by introducing SID to the detection set-up at GANIL. We also point possible application of this detector in alternative approach for superheavy elements production

New detector system for super heavy elements detection

A new detector system dedicated for very/super heavy elements (VHE/SHE) detection that decay by spontaneous fission is presented. Such a decay mode of nuclei can be found e.g. in the region of Z≈100 (Fermium). Future experiments realized in the frame of French-Polish collaboration at the cyclotrons in GANIL and in the Heavy Ion Laboratory (HIL), University of Warsaw, is described. The results of test measurements made in the HIL for reactions 20Ne(8 A.MeV)+120Sn, 179Au are presented

Gas scintillation chamber for superheavy elements detection at GANIL

In the paper we present scintillation-ionization detector (SID) - a new device for support of the superheavy elements (SHE) identification in the standard, complete fusion methods. We highlight problems with background effects in SHE production and their minimization by introducing SID to the detection set-up at GANIL. We also point possible application of this detector in alternative approach for superheavy elements production.SCOPUS: ar.jinfo:eu-repo/semantics/publishe