Size and time dependences of the valence states of Sn ions in amphoteric tin oxide nanoparticles

S. Tsunekawa, J. Kang, K. Asami, Y. Kawazoe, A. Kasuya

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)


Sn 3d core-level spectra are measured by X-ray photoelectron spectroscopy (XPS) for nearly monodisperse acidic and alkaline SnO 2-x nanoparticles in the size range 3-4 nm (original) and 1.5-2.5 nm (ultrafiltrated) in diameter. The comparison between the spectra obtained from the acidic and alkaline filtrated samples reveals that the difference is small after a few days but very large after 3 months. The acidic samples show little change in the peak positions and the Sn valence remains around 2.9. The alkaline samples exhibit an increase in the binding energy of more than 0.1 eV and the Sn valence increases up to 3.60 after 3 months. The fact that the lattice strain and the valence change of the Sn ions in the alkaline samples are larger than those in the acidic samples is well explained by surface coating and structure, in which the tin oxalate in the acidic samples is much more stable than the ammonium tin oxide in the alkaline samples.

Original languageEnglish
Pages (from-to)69-74
Number of pages6
JournalApplied Surface Science
Issue number1-4
Publication statusPublished - 2002 Nov 30


  • Amphoteric oxide
  • Lattice strain
  • Monodisperse
  • Oxidation
  • Tin oxide
  • Valence state

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films


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