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

doi:10.1021/cm500646f

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 journal › Article › peer-review

10 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 language	English (US)
Pages (from-to)	2726-2732
Number of pages	7
Journal	Chemistry of Materials
Volume	26
Issue number	8
DOIs	https://doi.org/10.1021/cm500646f
State	Published - Apr 9 2014

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: S.R.S.K., H.N.A., and T.M.T. acknowledge the financial support of the KAUST Competitive Faculty-Initiated Collaboration Grant.

ASJC Scopus subject areas

Materials Chemistry
General Chemical Engineering
General Chemistry

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@article{fad10ed453924f599bce53db49f077c9,

title = "Thermoelectric properties of strontium titanate superlattices incorporating niobium oxide nanolayers",

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. {\textcopyright} 2014 American Chemical Society.",

author = "{Sarath Kumar}, {S. R.} and Hedhili, {Mohamed N.} and Cha, {Dong Kyu} and TRITT, {TERRY M.} and Alshareef, {Husam N.}",

note = "KAUST Repository Item: Exported on 2020-10-01 Acknowledgements: S.R.S.K., H.N.A., and T.M.T. acknowledge the financial support of the KAUST Competitive Faculty-Initiated Collaboration Grant.",

year = "2014",

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T1 - Thermoelectric properties of strontium titanate superlattices incorporating niobium oxide nanolayers

AU - Sarath Kumar, S. R.

AU - Hedhili, Mohamed N.

AU - Cha, Dong Kyu

AU - TRITT, TERRY M.

AU - Alshareef, Husam N.

N1 - KAUST Repository Item: Exported on 2020-10-01 Acknowledgements: S.R.S.K., H.N.A., and T.M.T. acknowledge the financial support of the KAUST Competitive Faculty-Initiated Collaboration Grant.

PY - 2014/4/9

Y1 - 2014/4/9

N2 - 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.

AB - 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.

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Thermoelectric properties of strontium titanate superlattices incorporating niobium oxide nanolayers

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