Thermal Conductivities and Thermal Expansion Coefficients of (Sm0.5Gd0.5)2(Ce1−xZrx)2O7 Ceramics

• Published in: Journal of materials engineering and performance 2015-09, Vol.24 (9), p.3394-3399
• Main Authors: Hongsong, Zhang, Lei, Shi, Yongde, Zhao, Gang, Li, Zhenjun, Li
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Corrosion and Coatings; Engineering Design; Materials Science; Quality Control; Reliability; Safety and Risk; Tribology
• ISSN: 1059-9495; 1544-1024
• DOI: 10.1007/s11665-015-1621-z

The (Sm 0.5 Gd 0.5 ) 2 (Ce 1− x Zr x ) 2 O 7 oxides were prepared by solid-state reaction, and their phase compositions, microstructures, and thermophysical properties were investigated. Results of x-ray diffraction reveal that pure (Sm 0.5 Gd 0.5 ) 2 (Ce 1− x Zr x ) 2 O 7 oxides with fluorite structure are successfully synthesized in the current study. The thermal expansion coefficient decreases with increasing content of ZrO 2 , which is higher than that of 7 wt.% yttria-stabilized zirconia (YSZ). The substitution of Zr 4+ for Ce 4+ reduces the thermal conductivity of Sm 2 Ce 2 O 7 oxide. The thermal conductivity decreases from 1.69 W/m K ( x  = 0) to 1.22 W/m K ( x  = 0.3) at 1000 °C. The composition with x  = 0.3 exhibits the lowest thermal conductivity at all temperatures, and the thermal conductivity of (Sm 0.5 Gd 0.5 ) 2 (Ce 1− x Zr x ) 2 O 7 ceramics was obviously lower than those of fully dense 7 wt.% YSZ. These results suggested promising potential applications of the (Sm 0.5 Gd 0.5 ) 2 (Ce 1− x Zr x ) 2 O 7 ceramics for high-temperature thermal barrier coatings.