Potential oscillations during the electrochemical self-assembly of copper/cuprous oxide layered nanostructures
- PDF / 274,307 Bytes
- 8 Pages / 612 x 792 pts (letter) Page_size
- 92 Downloads / 132 Views
MATERIALS RESEARCH
Welcome
Comments
Help
Potential oscillations during the electrochemical self-assembly of copper/cuprous oxide layered nanostructures Jay A. Switzer,a) Chen-Jen Hung, Ling-Yuang Huang, F. Scott Miller, Yanchun Zhou, Eric R. Raub, Mark G. Shumsky, and Eric W. Bohannan Department of Chemistry and Graduate Center for Materials Research, University of Missouri, Rolla, Rolla, Missouri 65409-1170 (Received 17 September 1997; accepted 6 January 1998)
Layered nanostructures of copper metal and cuprous oxide are electrodeposited from alkaline solutions of Cu(II) lactate at room temperature. No subsequent heat treatment is necessary to effect crystallization. The electrode potential spontaneously oscillates during constant-current deposition. At a fixed current density the oscillation period decreases as either the pH or temperature is increased. The oscillations are periodic in stirred solution, but show period doubling and evidence of quasi-periodic or chaotic behavior in unstirred solution. The phase composition and resistivity of the films can be controlled by varying the applied current density. The resistivity of the films can be varied over ten orders of magnitude. Scanning electron microscopy shows that the films are layered.
I. INTRODUCTION
Interest in nanoscale and nanophase materials stems from the fact that the properties (optical, electrical, mechanical, and chemical) are a function of the dimensions of the material. The concept here is not to see how many transistors can be squeezed onto a chip, but, rather, to grow materials in a nanoscale size regime, in which some normally intrinsic property such as a semiconductor bandgap can be tuned by simply changing the dimensions of the material. Superlattices and multilayers are particularly interesting subclasses of these designer solids, since they have nanoscale confinement dimensions for electrons in the solid, yet they can be grown as large area films or even monolithic solids. This aspect of these materials makes them easily amenable to device manufacture. Our approach to the nanoregime has been electrodeposition. In particular, we are interested in producing nanostructures of inorganic materials such as oxide ceramics and metal oxide semiconductors. Metal oxides can be produced using either a redox change method or the electrochemical generation of base.1,2 In the redox method, a metal ion or complex is placed in a solution at a pH at which the starting oxidation state is stable but the oxidized (or reduced) form of the ion undergoes hydrolysis to form the oxide. We have used the redox method to produce thallium(III) oxide,3–5 lead(IV) oxide,6 silver(II) oxide,7 copper(I) oxide,8 the oxysalt Ag(Ag3 O4 )2 NO3 ,6 and superlattices in the Pb–Tl–O system.9–15 All of the redox depositions were done using anodic reactions except for the case of Cu2 O, which was deposited by a)
Author to whom correspondence should be addressed. e-mail: [email protected] J. Mater. Res., Vol. 13, No. 4, Apr 1998
http://journals.cambridge.org
Downloaded: 24 Feb
Data Loading...
