Journal
ACTA MATERIALIA
Volume 60, Issue 20, Pages 7024-7033Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2012.08.063
Keywords
Y3+-doped La2Zr2O7; Pyrochlore; Thermal conductivity; Resonant phonon scattering
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The evolution of structure and thermal conductivity (k) has been studied for a range of Y-La2Zr2O7 solid solutions. Within the pyrochlore range (x < 0.40) Y3+ solely substitutes for La3+ below a critical composition factor (x = 0.15), above which it substitutes for both La3+ and the Zr4+. A glass-like k, approaching the amorphous limit, is observed within a certain composition range (0.20 <= x < 0.40). The glass-like k behaviour is attributed to a phonon localization effect that arises from small and weakly bound Y3+ cations (rattlers) oscillating locally and independently in oversized anionic cages [(La/Y)O-8]. The ultralow and glassy k makes Y3+-doped La2Zr2O7 pyrochlores promising candidate materials for high temperature thermal barrier coating topcoats. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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