Chemisorption-driven reversible property tuning of nanophase metals and metal oxides
Thomas Traußnig
Institute of Materials Physics/TU Graz
15:00 - 16:00 Tuesday 22 June 2010 New York

Charge- or electrical field-induced tuning of materials properties is usually restricted to non-metals such as semiconductors and piezoelectric ceramics. It could be shown recently that such a tuning can also be achieved with metals when the limits associated with the efficient electronic screening are overcome by a high number of interfaces, i.e., a high surface-to-volume ratio, as available in highly porous nanophase metals. The present work aims at tuning the electrical resistance and the magnetic moment in metals and metal oxides reversibly. One focus is the utilization of reversible surface adsorption/desorption processes which significantly influence the materials properties.
In the field of resistance tuning we work with nanoporous Au which is dealloyed. Upon electrochemical charging a reversible change in resistance of up to 43% can be achieved.
On investigating the tunability of magnetism in metals and metal oxides reversible variations of the magnetic moment of up to 10% could be achieved upon charging of gamma-Fe2O3/Pt nanocomposites.
Studying nanocrystalline Co prepared by inertgas condensation yielded a reversible change of the magnetic moment of up to 1%.
The underlying processes of chemisorption at the sample surface will be discussed.