Order–Disorder Transition and Unconventional Thermal Conductivities of the (Sm1−xYbx)2Zr2O7 Series

Authors

  • Chunlei Wan,

    1. State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
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  • Zhixue Qu,

    1. State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
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  • Aibing Du,

    1. State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
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  • Wei Pan

    Corresponding author
    1. State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
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  • D. R. Clarke—contributing editor

  • This work was financially supported by the National Natural Science Foundation of China (Nos. 50232020 and 50572042).

†Author to whom correspondence should be addressed. e-mail: panw@mail.tsinghua.edu.cn

Abstract

Low-thermal-conductivity rare earth zirconates (Re2Zr2O7) have recently been identified as promising thermal barrier coating materials. We observed an order–disorder transition in the (Sm1−xYbx)2Zr2O7 series with the changing x value and investigated the thermal conductivity variation. Structural analysis by X-ray diffraction and Raman spectroscopy shows that the (Sm1−xYbx)2Zr2O7 series undergo a discontinuous phase transition from an ordered pyrochlore phase to a disordered fluorite one between the x=1/6 and x=1/3 compositions. Meanwhile, both of the sound velocity and Young's modulus reveal a dramatic reduction, indicating the lattice softening accompanying the order–disorder transition. The thermal conductivities of the (Sm1−xYbx)2Zr2O7 series are different from the conventional behavior of a simple alloying system and show a minimum thermal conductivity value at the transition composition (Sm2/3Yb1/3)2Zr2O7, which possibly arises from the enhanced phonon scattering due to the lattice softening.

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