Thermal properties of La₃TaO₇ and La₂AlTaO₇ oxides

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• 作者：Zhang Haoming^a ; Feng Yan^b ; Chen Xiaoge^c ; Zhang Hongsong^a ; ^{zhsandchen@126.com" class="auth_mail" title="E-mail the corresponding author} ; Liu Yanxu^a ; Tang An^a ; Ren Bo^a
• 关键词：Ceramics ; Thermal barrier coatings ; Thermal conductivity ; Thermal expansion coefficient
• 刊名：Ceramics International
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：43
• 期：1
• 页码：755-759
• 全文大小：844 K

文摘

The La₃TaO₇ and La₂AlTaO₇ oxides were prepared by solid state reaction method. The phase composition, microstructure and thermal properties were examined. Results show that pure La₃TaO₇ and La₂AlTaO₇ oxides are prepared successfully. From 20 °C to 1200 °C, the average thermal conductivities of La₃TaO₇ and La₂AlTaO₇ ceramics are 1.12 W/m K and 1.71 W/m K, respectively, which are much lower than that of YSZ. Compared to La₂AlTaO₇, La₃TaO₇ has lower thermal conductivity due to its higher atom-mass difference between the substituting and the substituted atoms. The thermal expansion coefficient of La₃TaO₇ is higher than that of YSZ, and the thermal expansion coefficient of La₂AlTaO₇ is close to that of YSZ. As compared with La₂AlTaO₇, the higher thermal expansion coefficient of La₃TaO₇ can be ascribed to its lower electro-negativity difference between ions at sites A and B. The La₃TaO₇ and La₂AlTaO₇ oxides can be explored as potential ceramic materials for thermal barrier coatings.