Spontaneous formation of nanostructures during pulsed laser deposition of epitaxial half-Heusler TiNiSn on MgO(001)

R. W. H. Webster, J. E. Halpin, Srinivasa R. Popuri, Jan-Willem G. Bos, D. A. Maclaren

Research output: Contribution to journalArticle

Abstract

The half-Heusler alloy TiNiSn is a promising material for thermoelectric applications that is inexpensive and non-toxic. We demonstrate the epitaxial growth of smooth TiNiSn thin films on MgO(001) single crystal substrates by pulsed laser deposition, using transmission electron microscopy to investigate nanoscale structural and chemical inhomogeneities. In particular, an interfacial reaction results in the formation of a titanium-rich oxide nanolayer at the substrate interface, and this maintains epitaxy but perturbs film composition. Segregation effects are observed throughout the film, producing a narrow range of off-stoichiometric, half-Heusler compositions. The propensity of titanium to oxidise also leads to the commensurate formation of parasitic titanium oxide nanostructures which may be overlooked in bulk techniques but are a key feature that drives both the formation of Ni-enriched, full-Heusler phases and the local decomposition of the half-Heusler to form additional nickel-stannide phases.

LanguageEnglish
Article number013206
JournalAPL Materials
Volume7
Issue number1
Early online date17 Dec 2018
DOIs
Publication statusPublished - Jan 2019

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Pulsed laser deposition
Titanium
Epitaxial growth
Nanostructures
Titanium oxides
Substrates
Surface chemistry
Nickel
Chemical analysis
Oxides
Single crystals
Transmission electron microscopy
Decomposition
Thin films
titanium dioxide

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)

Cite this

Webster, R. W. H. ; Halpin, J. E. ; Popuri, Srinivasa R. ; Bos, Jan-Willem G. ; Maclaren, D. A. / Spontaneous formation of nanostructures during pulsed laser deposition of epitaxial half-Heusler TiNiSn on MgO(001). In: APL Materials. 2019 ; Vol. 7, No. 1.
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Spontaneous formation of nanostructures during pulsed laser deposition of epitaxial half-Heusler TiNiSn on MgO(001). / Webster, R. W. H.; Halpin, J. E.; Popuri, Srinivasa R.; Bos, Jan-Willem G.; Maclaren, D. A.

In: APL Materials, Vol. 7, No. 1, 013206, 01.2019.

Research output: Contribution to journalArticle

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