High entropy(Yb_0.25Y_0.25Lu_0.25Er_0.25)₂SiO₅ with strong anisotropy in thermal expansion

Heng Chen^1,2，Huimin Xiang²，Fu-Zhi Dai²，Jiachen Liu³，Yanchun Zhou²

1. Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of Education,School of Materials Science and Engineering, Tianjin University2. Science and Technology on Advanced Functional Composite Laboratory, Aerospace Research Institute of Materials & Processing Technology3. Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of Education, School of Materials Science and Engineering, Tianjin University

摘 要：A novel high entropy（HE） rare earth monosilicate(Yb_0.25Y_0.25Lu_0.25Er_0.252 SiO₅ was synthesized by solid-state reaction method.X-ray diffraction and scanning electron microscopy analysis indicate that a single solid solution is formed with homogeneous distribution of rare-earth elements.HE(Yb_0.25Y_0.25Lu_0.255 Er_0.252 SiO₅ exhibits excellent phase stability and anisotropy in thermal expansion.The coefficients of thermal expansion（CTEs） in three crystallographic directions are:α_a=（2.57±0.07）×10^-6 K^-1,α_b=（8.07±0.13）×10^-6 K^-1,α_c=（9.98±0.10）×10^-6 K^-1.The strong anisotropy in thermal expansion is favorable in minimizing the coating/substrate mismatch if preferred orientation of HE(Yb_0.25Y_0.25Lu_0.25Er_0.252 SiO₅ is controlled on either metal or ceramic substrate.

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