Catherine Y. Han

Publications (2)0 Total impact

• Article: Fabrication of Alumina Nanotubes and Nanowires by Etching Porous Alumina Membranes

  Z. L. Xiao, Catherine Y. Han, U. Welp, H. H. Wang, W. K. Kwok, G. A. Willing, J. M. Hiller, R. E. Cook, D. J. Miller, G. W. Crabtree
  [show abstract] [hide abstract]
  ABSTRACT: Porous alumina membranes are commercially available and have been widely used in recent nanoscale research, for example, as templates in nanowire fabrication through electrodeposition. In this report, we present a new use for porous alumina membranes in the fabrication of alumina nanotubes/nanowires desired in electrochemical devices and catalytic applications. A high yield of alumina nanotubes/nanowires is obtained by etching porous alumina membranes in an aqueous sodium hydroxide solution. We studied the effects of etching time and solution concentration and characterized the alumina nanotubes/nanowires using a scanning electron microscope (SEM). A discussion of the possible mechanism for the formation of nanotubes/nanowires is given. Our results also imply that in nanowire fabrication through the template approach where alumina membranes are removed with sodium hydroxide solution to release the nanowires special attention is needed in characterizing the nanowires with the SEM because alumina nanotubes/nanowires can be easily mistaken for electrodeposited nanowires.
  10/2002;
• Source

  Available from: Jon Hiller

  Article: Nickel Antidot Arrays on Anodic Alumina Substrates

  Z. L. Xiao, Catherine Y. Han, U. Welp, H. H. Wang, V. K. Vlasko-Vlasov, W. K. Kwok, D J Miller, J. M. Hiller, R. E. Cook, G. A. Willing, G. W. Crabtree
  [show abstract] [hide abstract]
  ABSTRACT: Large area nickel antidot arrays with density up to 10^10 /cm^2 have been fabricated by depositing nickel onto anodic aluminum oxide membranes that contain lattices of nanopores. Electron microscopy images show a high degree of order of the antidot arrays. Various sizes and shapes of the antidots were observed with increasing thickness of the deposited nickel. New features appear in the antidot arrays in both magnetization and transport measurements when the external magnetic field is parallel to the current direction, including an enhancement and a nonmonotonous field dependence of the magnetoresistance, larger values of the coercive field and remanence moment, and smaller saturation field.
  08/2002;