Growth and characterization of vertically aligned self-assembled IrO 2 nanotubes on oxide substrates

R. S. Chen, H. M. Chang, Y. S. Huang*, D. S. Tsai, S. Chattopadhyay, K. H. Chen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

58 Scopus citations


The self-assembled vertically aligned iridium dioxide nanotubes (IrO 2 NTs) have been successfully grown on sapphire (SA)(1 0 0) and LiNbO3 (LNO)(1 0 0) substrates, via metalorganic chemical vapor deposition (MOCVD), using (MeCp)Ir(COD) as the source reagent. The surface morphology and structural properties of the as-grown NTs were characterized in detail using field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected area electron diffractometry (SAD), X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). FESEM images and XRD patterns revealed that the well-aligned and single-crystalline NTs were grown normal to the substrates. TEM and SAD measurements showed that the hollow IrO2 NTs with square cross section have open-end morphology and long axis directed along the [0 0 1] direction. Analysis of the growth pattern indicated that the IrO2 NTs on SA(1 0 0) and LNO(1 0 0) grow with the orientation relationship given by IrO2(0 0 1)// SA(1 0 0), IrO 2[1 0 0]// SA[0 1 0] and IrO2(0 0 1)// LNO(1 0 0), IrO2[1 0 0]// LNO[0 1 0], respectively. XPS spectra show the existence of a higher oxidation state of iridium in IrO2 NTs. The probable mechanism for the formation of the vertically aligned NTs is discussed.

Original languageEnglish
Pages (from-to)105-112
Number of pages8
JournalJournal of Crystal Growth
Issue number1-2
StatePublished - 15 Oct 2004


  • Field-emission scanning electron microscopy
  • IrO
  • Metalorganic chemical vapor deposition
  • Nanotube
  • Transmission electron microscopy
  • X-ray diffractometry
  • X-ray photoelectron spectroscopy


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