Thermal conductivity and expansion coefficient of Ln₂LaTaO₇ (Ln=Er and Yb) oxides for thermal barrier coating applications

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• 作者：Chen Xiaoge^a ; Tang An^b ; Zhang Hongsong^b ; ^{zhsandchen@126.com" class="auth_mail" title="E-mail the corresponding author} ; Liu Yanxu^b ; Zhang Haoming^b ; Zhao Yongde^c
• 关键词：Thermal barrier coatings ; Fluorite-type ceramics ; Thermal conductivity ; Thermal expansion
• 刊名：Ceramics International
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：42
• 期：12
• 页码：13491-13496
• 全文大小：1341 K

文摘

Two kinds of novel Ln₂LaTaO₇ (Ln=Er and Yb) ceramics were prepared via high-temperature solid reaction method. The phase composition, micro-morphology and thermophysical properties were investigated. Results indicate that pure Ln₂LaTaO₇ ceramics with single fluorite-type structure are synthesized successfully. The thermal conductivities of Er₂LaTaO₇ and Yb₂LaTaO₇ are in the range of 1.22–1.43 W/m K and 1.17–1.51 W/m K, respectively, which are much lower than that of YSZ. The lower thermal conductivity can be attributed to the phonon scattering caused by oxygen vacancies and the substituting atoms. The average thermal expansion coefficients of Yb₂LaTaO₇ and Er₂LaTaO₇ are 9.94×10⁻⁶/K and 9.63×10⁻⁶/K, respectively. As compared with Yb₂LaTaO₇, the higher thermal expansion coefficient of Er₂LaTaO₇ can be ascribed to its lower ionic-bond strength between cations at sites A and B.