Reduced thermal conductivity by nanoscale intergrowths in perovskite like layered structure La2Ti2O

Journal article (2015)
Department
Aerospace Structures & Materials (Aerospace Engineering) (TU Delft)
Copyright: © 2015 American Institute of Physics
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Published Date

18-02-2015

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Source:

Journal of Applied Physics, 117 (7), 2015

Faculty

Aerospace Engineering

Department

Aerospace Structures & Materials

Abstract

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 La2Ti2O7. 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 La2Ti2O7 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 La2Ti2O7 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 La2Ti2O7 and ?0.93?W/m K for Ta doped La2Ti2O7 at 573?K.

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