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Portrait of Reine Wallenberg. Photo: Kennet Ruona

Reine Wallenberg

Professor, Coordinator Materials Science

Portrait of Reine Wallenberg. Photo: Kennet Ruona

Tin-oxide nanoparticles deposited from a beam : what happens to the composition?

Author

  • M. Tchaplyguine
  • C. Wright
  • A. Shavorskiy
  • S. Zhu
  • M. H. Mikkelä
  • C. Zhang
  • O. Björneholm
  • E. Mårsell
  • A. Mikkelsen
  • S. Sorensen
  • C. J.D. Hetherington
  • L. R. Wallenberg

Summary, in English

The debate around the oxidation states occurring in laboratory-prepared tin-oxide samples has been for a long time an obstacle for an unambiguous assignment of characterization studies performed on such samples. In particular the changes in the Sn core-level energies caused by oxidation - i.e. the chemical shifts - as measured by photoelectron spectroscopy (PES) have been under discussion. The assignment problem is especially pronounced for nanoscale structures, which are important for photovoltaics, electronics, catalysis, and gas sensing. The reasons for the difficulties lie both in the natural properties of tin oxides, which can have substantial deficiencies of oxygen and tin in the lattice, and in the shortcomings of the fabrication and PES-characterization procedures themselves. Our recent PES study on tin-oxide nanoparticles fabricated by vapour-aggregation gave a chemical shift two times larger than earlier reported for Sn(iv) oxide for the Sn 4d level. The implemented fabrication technique forms an in-vacuum beam of particles whose composition can be both controlled and characterized by PES. In the present work SnO and SnO2 nanoparticles fabricated this way were deposited from the beam and probed by PES directly, as well as after exposure to air. The deposited nanoparticle films were also imaged by TEM (Transmission Electron Microscopy). The effects of the deposition process and exposure to air on the chemical composition were studied. The PES study of deposited SnO2 nanoparticles in the Sn 4d and Sn 3d core-level regions revealed the same core level shift as for unsupported nanoparticles, indicating that the chemical composition is preserved in the deposition process. The TEM study demonstrated a crystalline structure of separate SnO2 particles with lattice constants close to the macroscopic Sn(iv)-oxide. The PES study on the particles exposed to air showed changes in the composition. For the film of initially SnO particles a higher intermediate oxide was created. For the SnO2 nanoparticle film a lower, but strong, intermediate oxide was observed, likely at the surface.

Department/s

  • MAX IV Laboratory
  • Synchrotron Radiation Research
  • NanoLund
  • University Management
  • Centre for Analysis and Synthesis

Publishing year

2019

Language

English

Pages

6287-6295

Publication/Series

Physical chemistry chemical physics : PCCP

Volume

21

Issue

11

Document type

Journal article

Publisher

Royal Society of Chemistry

Topic

  • Physical Chemistry

Status

Published

ISBN/ISSN/Other

  • ISSN: 1463-9084