Fabrication of Crystalline $ZrO_2$ Nanotubes by ALD

  • 김현철 (산화물나노튜브응용연구실, 자기조립소재공정연구센터) ;
  • ;
  • 유현준 (산화물나노튜브응용연구실, 자기조립소재공정연구센터) ;
  • 김명준 (산화물나노튜브응용연구실, 자기조립소재공정연구센터) ;
  • 양윤정 (산화물나노튜브응용연구실, 자기조립소재공정연구센터) ;
  • 이선희 (산화물나노튜브응용연구실, 자기조립소재공정연구센터) ;
  • 신현정 (산화물나노튜브응용연구실, 자기조립소재공정연구센터)
  • Published : 2011.05.27

Abstract

Numerous possible applications for $ZrO_2$ nanotubes exist such as for catalyst support structures, for sensing or for applications as a solid state electrolyte. Especially, because of a large specific surface area, high efficiency for solid oxide fuel cell (SOFC) application at low temperature can be expected for nanotublar structures in even small size. A zirconium precursor, Tetrakis (ethylmethylamino) zirconium, TEMAZr and $H_2O$ oxidant were used to deposit$ZrO_2$ thin films on an anodized aluminum oxide (AAO) templates having sub-100nm cylindrical pores by atomic layer deposition (ALD) in the temperature range of 150~250$^{\circ}C$. The crystalline structures of as-prepared and post-annealed $ZrO_2$ nanotubes were characterized by x-ray diffraction and high-resolution transmission electron microscopy. The as-prepared samples at $150^{\circ}C$ and $200^{\circ}C$ were showed amorphous, whereas a mixed phase of tetragonal, monoclinic and amorphous polymorph was observed at $250^{\circ}C$. In the bulk, zirconia remains monoclinic phase up to $1,175^{\circ}C$, however, $ZrO_2$ nanotubes were showed tetragonal phase upon post thermal treatments merely at $400^{\circ}C$. This trend may be indicative of high-curvature surfaces of nanotubes and thereby the presence of intrinsic compressive strain. The amount of amorphous structures in the mixed phase as well as as-grown $ZrO_2$ nanotubes were also gradually decreased by subsequent heat treatment.

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