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Title: Reduced thermal conductivity by nanoscale intergrowths in perovskite like layered structure La{sub 2}Ti{sub 2}O{sub 7}

The effect of substitution and oxidation-reduction on the thermal conductivity of perovskite-like layered structure (PLS) ceramics was investigated in relation to mass contrast and non-stoichiometry. Sr (acceptor) was substituted on the A site, while Ta (donor) was substituted on the B site of La{sub 2}Ti{sub 2}O{sub 7}. Substitution in PLS materials creates atomic scale disorders to accommodate the non-stoichiometry. High resolution transmission electron microscopy and X ray diffraction revealed that acceptor substitution in La{sub 2}Ti{sub 2}O{sub 7} produced nanoscale intergrowths of n = 5 layered phase, while donor substitution produced nanoscale intergrowths of n = 3 layered phase. As a result of these nanoscale intergrowths, the thermal conductivity value reduced by as much as ∼20%. Pure La{sub 2}Ti{sub 2}O{sub 7} has a thermal conductivity value of ∼1.3 W/m K which dropped to a value of ∼1.12 W/m K for Sr doped La{sub 2}Ti{sub 2}O{sub 7} and ∼0.93 W/m K for Ta doped La{sub 2}Ti{sub 2}O{sub 7} at 573 K.
Authors:
;  [1] ;  [2] ; ;  [3] ;  [4] ; ;  [1] ;  [5]
  1. School of Engineering and Material Science, Queen Mary University of London, London E1 4NS (United Kingdom)
  2. Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education and International Centre for Dielectric Research, Xi'an Jiaotong University, Xi'an, 710049 (China)
  3. School of Engineering and Applied Science, Aston University, Birmingham B4 7ET (United Kingdom)
  4. Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS Delft (Netherlands)
  5. (United Kingdom)
Publication Date:
OSTI Identifier:
22413139
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 7; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CERAMICS; DOPED MATERIALS; LANTHANUM COMPOUNDS; NANOSTRUCTURES; OXIDATION; PEROVSKITE; REDUCTION; TANTALUM COMPOUNDS; THERMAL CONDUCTIVITY; TITANATES; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION