Berlin 2008 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 4: Nanostructured Materials I
MM 4.1: Vortrag
Montag, 25. Februar 2008, 10:15–10:30, H 0107
Electrochemically induced surface charge effect on the properties of nanoporous Au-Fe alloys — •Ajay Kumar Mishra1, Chandrahas Bansal1,2, and Horst Hahn1 — 1Institute for Nanotechnology, Forschungszentrum Karlsruhe, Karlsruhe 76021, Germany — 2School of Physics, University of Hyderabad, Hyderabad 500 046, India
Nanoporous Au-Fe alloys consisting of nanoparticles of about 5 nm diameter were synthesized by inert gas phase condensation. Charge was induced electrochemically on the surface of the nanoparticles, and in-situ measurements of strain, magnetization, and conductivity were carried out during the charging and decharging process taking place in the electrochemical cell. The observed strain could be explained to arise from a Coulomb pressure produced by the surface charge on the metal. The variation of magnetization with charging was also found to be consistent with the effect of this pressure. A charge induced variation in the dc electrical conductivity of about 6 percent was observed. An explanation of the rate of change of conductivity with charge was provided in terms of the additional charge density produced by the induced charge. Similarly at the microscopic level, Mossbauer isomer shift and quadrupole splitting were measured and showed a small but reversible behaviour with charge.