期刊
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
卷 38, 期 10, 页码 3547-3554出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.jeurceramsoc.2018.04.021
关键词
Rare-earth disilicates; Thermal/environmental barrier coating; Thermal expansion; Phonon anharmonicity; Density functional theory
资金
- National Key R&D Program of China [2017YFB0703201]
- Natural Science Foundation of China [51402311, 51772302]
Optimization of thermal expansion coefficient (CTE) mismatch among constituent rare-earth silicate layers is a critical challenge for the optimal multilayer thermal/environmental barrier coating (T/EBC) architecture for SiCf/SiCm CMCs. In this study, thermal expansion properties for beta-, gamma- and delta-RE2Si2O7 polymorphs are investigated via DFT calculations. The interaction between rare-earth (RE) atoms and neighboring bridging oxygen ((OB)) atoms, as well as the structure of [O3Si-(OB)-Si0(3)] pyrosilicate units are the characteristic gene that controls the positive or negative contribution from low-frequency vibration patterns to the overall phonon anharmonicity, and eventually determine the significantly different CTE of RE2Si2O7 polymorphs. Inspired by the concept of genome modification, gamma-(Dy0.15Y0.85)(2)Si2O7 solid solution is designed and synthesized, which shows notable enhancements of CTE as compared with gamma-Y(2)si(2)O(7). Such tunable CTE could presumably be explained by doping-induced localized lattice distortion around [O3Si-O-B-SiO3] pyrosilicate units, leading to switchable magnitude of negative contribution from low-frequency phonons to thermal expansion.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据