Tunable thermal properties in yttrium silicates switched by anharmonicity of low-frequency phonons

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	Tunable thermal properties in yttrium silicates switched by anharmonicity of low-frequency phonons
	Luo, YX; Sun, LC; Wang, JM; Tian, ZL; Nian, HQ; Wang, JY; Wang, JY (reprint author), Chinese Acad Sci, Inst Met Res, High Performance Ceram Div, Shenyang Natl Lab Mat Sci, Shenyang 110016, Liaoning, Peoples R China.
刊名	JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
	2018-04-01
卷号	38 期号:4 页码:2043-2052
关键词	Environmental Barrier Coatings Molten-salt Corrosion Functional Perturbation-theory Silicon-nitride Si3n4 Ceramics Expansion Conductivity Y2sio5 Gamma-y2si2o7 Composites
ISSN号	0955-2219
英文摘要	Coordinated modulation of thermal resistance and thermal expansion compatibility has become a chief concern in designing reliable environmental/thermal barrier coating candidates for Si-based ceramics. This study reports phonon behaviors and thermal properties of prototypical silicates X-2-Y2SiO5 and gamma-Y2Si2O7. The nature of an-harmonicity for low-frequency phonons is analyzed, and the finding is discussed with respect to specific crystal structures and interatomic force constants. Low lattice thermal conductivities (KJ basically derive from the giant phonon anharmonicity enhanced by interactions between low-frequency optic and acoustic phonons. gamma-Y2Si2O7 is predicted with considerably lower thermal expansion coefficient (av) than Y2SiO5. The mechanism is disclosed as an effect of the extensive number of low-frequency phonons with negative Griineisen constants (contributing to negative thermal expansion) in gamma-Y2Si2O7, together with its higher elastic stiffness against internal thermal pressure at elevated temperature. A guideline for simultaneously approaching low CL and low av is proposed for searching promising E/TBC candidates.; Coordinated modulation of thermal resistance and thermal expansion compatibility has become a chief concern in designing reliable environmental/thermal barrier coating candidates for Si-based ceramics. This study reports phonon behaviors and thermal properties of prototypical silicates X-2-Y2SiO5 and gamma-Y2Si2O7. The nature of an-harmonicity for low-frequency phonons is analyzed, and the finding is discussed with respect to specific crystal structures and interatomic force constants. Low lattice thermal conductivities (KJ basically derive from the giant phonon anharmonicity enhanced by interactions between low-frequency optic and acoustic phonons. gamma-Y2Si2O7 is predicted with considerably lower thermal expansion coefficient (av) than Y2SiO5. The mechanism is disclosed as an effect of the extensive number of low-frequency phonons with negative Griineisen constants (contributing to negative thermal expansion) in gamma-Y2Si2O7, together with its higher elastic stiffness against internal thermal pressure at elevated temperature. A guideline for simultaneously approaching low CL and low av is proposed for searching promising E/TBC candidates.
学科主题	Materials Science, Ceramics
语种	英语
资助机构	National Key R&D Program of China [2017YFB0703201]; Natural Science Foundation of China [51372252, 51772302]
公开日期	2018-06-05
内容类型	期刊论文
源URL	[http://ir.imr.ac.cn/handle/321006/79416]
专题	金属研究所_中国科学院金属研究所
通讯作者	Wang, JY (reprint author), Chinese Acad Sci, Inst Met Res, High Performance Ceram Div, Shenyang Natl Lab Mat Sci, Shenyang 110016, Liaoning, Peoples R China.
推荐引用方式 GB/T 7714	Luo, YX,Sun, LC,Wang, JM,et al. Tunable thermal properties in yttrium silicates switched by anharmonicity of low-frequency phonons[J]. JOURNAL OF THE EUROPEAN CERAMIC SOCIETY,2018,38(4):2043-2052.
APA	Luo, YX.,Sun, LC.,Wang, JM.,Tian, ZL.,Nian, HQ.,...&Wang, JY .(2018).Tunable thermal properties in yttrium silicates switched by anharmonicity of low-frequency phonons.JOURNAL OF THE EUROPEAN CERAMIC SOCIETY,38(4),2043-2052.
MLA	Luo, YX,et al."Tunable thermal properties in yttrium silicates switched by anharmonicity of low-frequency phonons".JOURNAL OF THE EUROPEAN CERAMIC SOCIETY 38.4(2018):2043-2052.