Thermoelectric properties of strontium titanate superlattices incorporating niobium oxide nanolayers

S. R. Sarath Kumar, Mohamed N. Hedhili, Dong Kyu Cha, TERRY M. TRITT, Husam N. Alshareef

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

A novel superlattice structure based on epitaxial nanoscale layers of NbOx and Nb-doped SrTiO3 is fabricated using a layer-by-layer approach on lattice matched LAO substrates. The absolute Seebeck coefficient and electrical conductivity of the [(NbOx) a/(Nb-doped SrTiO3)b]20 superlattices (SLs) were found to increase with decreasing layer thickness ratio (a/b ratio), reaching, at high temperatures, a power factor that is comparable to epitaxial Nb-doped SrTiO3 (STNO) films (∼0.7 W m-1 K-1). High temperature studies reveal that the SLs behave as n-type semiconductors and undergo an irreversible change at a varying crossover temperature that depends on the a/b ratio. By use of high resolution X-ray photoelectron spectroscopy and X-ray diffraction, the irreversible changes are identified to be due to a phase transformation from cubic NbO to orthorhombic Nb2O5, which limits the highest temperature of stable operation of the superlattice to 950 K. © 2014 American Chemical Society.
Original languageEnglish (US)
Pages (from-to)2726-2732
Number of pages7
JournalChemistry of Materials
Volume26
Issue number8
DOIs
StatePublished - Apr 9 2014

ASJC Scopus subject areas

  • Materials Chemistry
  • Chemical Engineering(all)
  • Chemistry(all)

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