Investigation of La3 + Doped Yb2Sn2O7 as new thermal barrier materials |
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| Affiliation: | 1. Department of Mechanical, Materials and Manufacturing Engineering, University of Nottingham, Nottingham NG7 2RD, UK;2. School of Chemistry, University of Nottingham, Nottingham NG7 2RD, UK;1. Department of Mechanical and System Engineering, Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671–2280, Japan;2. Department of Mechanical Engineering, National University Corporation-Kitami Institute of Technology, 165 Koen-cho, Kitami, Hokkaido 090–8507, Japan;3. Kitami Institute of Technology, 165 Koen-cho, Kitami, Hokkaido 090–8507, Japan;1. Queensland Centre for Advanced Materials Processing and Manufacturing (AMPAM), School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia;2. School of Science and Engineering, University of the Sunshine Coast, Sippy Downs, Queensland 4575, Australia;1. School of Materials, The University of Manchester, Manchester M13 9PL, United Kingdom;2. School of Mechanical, Aerospace & Civil Engineering, The University of Manchester, Manchester M13 9PL, United Kingdom;1. School of Materials Science and Engineering, Harbin University of Science and Technology, Harbin 150040, PR China;2. Southwest Technique and Engineering Institute, Chongqing 400039, PR China;1. Czech Technical University in Prague, Faculty of Nuclear Sciences and Physical Engineering, Department of Materials, Trojanova 13, 120 00 Praha 2, Czech Republic;2. Department of Physics of Materials, Charles University, Ke Karlovu 5, 121 16 Prague 2, Czech Republic;1. Key Laboratory of Superlight Materials & Surface Technology, Ministry of Education, Harbin Engineering University, Harbin 150001, PR China;2. Shenyang Jinbo Gas Compression Manufacturing Co. Ltd., Shenyang 110027, PR China |
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| Abstract: | Low thermal conductivity is one of the key requirements for thermal barrier coating materials. From the consideration of crystal structure and ion radius, La3 + Doped Yb2Sn2O7 ceramics with pyrochlore crystal structures were synthesized by sol–gel method as candidates of thermal barrier materials in aero-engines. As La3 + and Yb3 + ions have the largest radius difference in lanthanoid group, La3 + ions were expected to produce significant disorders by replacing Yb3 + ions in cation layers of Yb2Sn2O7. Both experimental and computational phase analyses were carried out, and good agreement had been obtained. The lattice constants of solid solution (LaxYb1 − x)2Sn2O7 (x = 0.3, 0.5, 0.7) increased linearly when the content of La3 + was increased. The thermal properties (thermal conductivity and coefficients of thermal expansion) of the synthesized materials had been compared with traditional 8 wt.% yttria stabilized zirconia (8YSZ) and La2Zr2O7 (LZ). It was found that La3 + Doped Yb2Sn2O7 exhibited lower thermal conductivities than un-doped stannates. Amongst all compositions studied, (La0.5Yb0.5)2Sn2O7 exhibited the lowest thermal conductivity (0.851 W·m− 1·K− 1 at room temperature), which was much lower than that of 8YSZ (1.353 W·m− 1·K− 1), and possessed a high coefficient of thermal expansion (CTE), 13.530 × 10− 6 K− 1 at 950 °C. |
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