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首页> 外文期刊>Journal of Materials Research >Theoretical study on crystal structures, elastic stiffness, and intrinsic thermal conductivities of β-, γ-, and δ-Y_2Si_2O_7
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Theoretical study on crystal structures, elastic stiffness, and intrinsic thermal conductivities of β-, γ-, and δ-Y_2Si_2O_7

机译：β-，γ-和δ-Y_2Si_2O_7的晶体结构，弹性刚度和固有热导率的理论研究

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摘要

Yttrium disilicates (Y_2Si_2O_7), well known for its complex polymorphism, are promising candidates for high-temperature structural materials and environmental barrier coatings due to their good properties in harsh environments. In this study, the crystal structure, elastic stiffness, and temperature dependence of the lattice thermal conductivity of β-, γ-, and δ-Y_2Si_2O_7 are studied using first-principles calculations. Divergences of elastic stiffness are attributed to the different crystal structures and bonding strength of the polymorphs. Specially, the Si-O-Si bridge of 8 phase bends with an angle of 158.1°, and this configuration enhances the bonding heterogeneity but weakens the bonding strength and stability. According to the prediction of lattice thermal conductivity using the Debye-Slack model, β-, γ-, and δ-Y_2Si_2O_7 are characterized with very low thermal conductivity. In addition, the deviation of lattice thermal conductivities of Y_2Si_2O_7 polymorphs is dominated by two vital factors, anharmonicity of phonon scattering and complexity of crystal structure. The present method could be used to investigate the specific factors dominating lattice thermal conductivity and may promisingly be generalized to search novel candidates with extremely low lattice thermal conductivity.
机译：二硅酸钇（Y_2Si_2O_7）以其复杂的多态性而闻名，由于其在恶劣环境中的良好性能，它们有望成为高温结构材料和环境屏障涂层的候选材料。在这项研究中，使用第一性原理计算研究了β-，γ-和δ-Y_2Si_2O_7的晶体结构，弹性刚度和晶格导热率的温度依赖性。弹性刚度的差异归因于多晶型物的不同晶体结构和结合强度。特别是，8相的Si-O-Si桥以158.1°的角度弯曲，这种结构增强了键合的异质性，但削弱了键合强度和稳定性。根据使用Debye-Slack模型预测的晶格热导率，β-，γ-和δ-Y_2Si_2O_7具有非常低的热导率的特征。另外，Y_2Si_2O_7多晶型的晶格热导率偏差受两个重要因素控制，即声子散射的非谐性和晶体结构的复杂性。本方法可用于研究决定晶格热导率的具体因素，并有望推广到搜索具有极低晶格热导率的新型候选物。

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  • 来源
    《Journal of Materials Research》 |2015年第4期|493-502|共10页
  • 作者

    Yixiu Luo; Jiemin Wang; Junning Li; Zijun Hu; Jingyang Wang;

  • 作者单位

    High-performance Ceramics Division, Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China;

    High-performance Ceramics Division, Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China;

    Science and Technology of Advanced Functional Composite Laboratory, Aerospace Research Institute of Materials and Processing Technology, Beijing 100076, China;

    Science and Technology of Advanced Functional Composite Laboratory, Aerospace Research Institute of Materials and Processing Technology, Beijing 100076, China;

    High-performance Ceramics Division, Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);
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