4th INTERNATIONAL WORKSHOP ON ELECTRODEPOSITED NANOSTRUCTURES 16-18 March 2006, Dresden, Germany	ABSTRACTS

THE EFFECTS OF MAGNETICALLY INDUCED FORCES ON THE ELECTRODEPOSITION M. Uhlemann, A. Krause, A. Gebert, L. Schultz Leibniz Institute for Solid State and Materials Research Dresden P.O. Box 270016, 01171 Dresden, Germany E-mail: m.uhlemann@ifw-dresden.de Magnetic field effects on electrochemical processes and on the morphology of the metal deposits are widely accepted but partially controversially discussed. The electrodeposition of paramagnetic ions (Cu and Co) and the change of the pH directly at the surface has been investigated with respect to the strength and the orientation of homogeneous magnetic fields and electrode geometry [1-3]. Two different convective effects caused by the magnetic field on the electrodeposition have been observed. The first well known MHD-effect is caused by the Lorentzforce FL and generates a macroscopic laminar or rotational convection outside of the diffusion layer. The second effect leads to micro-magneto convection inside the diffusion layer and is discussed with respect to gradient forces caused by the magnetic energy of the paramagnetic metal ions. It was found that in homogeneous magnetic fields the paramagnetic force Fp dominates the micro-magneto convection and is up to three orders of magnitude higher than the Lorenz force. The strength of the paramagnetic force depends on the paramagnetic susceptibility of the metal ions, the concentration gradient inside the diffusion layer, the magnetic properties of the substrate and the deposits itself and the deposition potential. For the Cu deposition the maximal paramagnetic force acts in the beginning of the deposition process and drops down after some seconds to a negligible value because of the low magnetic susceptibility. For Co deposition the paramagnetic force is low at the beginning due to the dominating hydrogen reaction. The maximal paramagnetic force is reached after some seconds and is one order of magnitude higher than for the Cu deposition because of the higher magnetic susceptibility of the Co ions. The concentration gradients and the resulting forces as well as overlapping effects are discussed and first calculations to the generated flow of the electrolyte close to the surface are presented as shown in Figure 1.     Figure 1: MHD-effect and micro-magneto convection inside the diffusion layer Acknowledgments: The German Research Council (DFG) is gratefully acknowledged for the support within the framework of the SFB 609. References: 1) A. Krause, M. Uhlemann, A. Gebert, Electrochim. Acta, 49 (2004) 4127. 2) M. Uhlemann, A. Krause, A. Gebert, Electroanal. Chem., 577 (2005) 19. 3) A. Krause, A. Ispaas, M. Uhlemann, A. Bund, Electrochim. Acta, 2005 submitted

 
 
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