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Theoretical Predictions on Elastic Stiffness and Intrinsic Thermal Conductivities of Yttrium Silicates
Author(s) -
Luo Yixiu,
Wang Jiemin,
Wang Jingyang,
Li Junning,
Hu Zijun
Publication year - 2014
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.12764
Subject(s) - thermal conductivity , materials science , yttrium , debye model , atmospheric temperature range , thermal , thermal conduction , thermodynamics , condensed matter physics , crystallographic defect , elastic modulus , lattice (music) , mineralogy , composite material , chemistry , metallurgy , oxide , physics , acoustics
Yttrium silicates are promising candidates for environmental and thermal barrier coatings owing to their excellent high‐temperature performances. Previous works have experimentally attested to their low thermal conductivity, nevertheless, the experimental data were significantly affected by measurement inaccuracy and the existence of defects such as point defects, dislocations, grain boundaries, and pores in measured samples. In this study, the temperature dependences of intrinsic lattice thermal conductivities of γ‐ Y 2 Si 2 O 7 and Y 2 SiO 5 are predicted based on the first‐principles calculations of crystal structure, elastic moduli, Debye temperature, and Grüneisen constant. Both silicates display very low thermal conductivities over the range of 300–2000 K; and in addition, Y 2 SiO 5 exhibits relatively lower thermal conductivity than γ‐ Y 2 Si 2 O 7 . We also show certain discrepancies between experimental and theoretical thermal conductivities, and it strengthens the important role of theoretical prediction of intrinsic lattice thermal conductivities of promising materials.