High entropy(Yb0.25Y0.25Lu0.25Er0.25)2SiO5 with strong anisotropy in thermal expansion

摘要

A novel high entropy(HE) rare earth monosilicate(Yb0.25Y0.25Lu0.25Er0.252 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(Yb0.25Y0.25Lu0.255 Er0.252 SiO5 exhibits excellent phase stability and anisotropy in thermal expansion.The coefficients of thermal expansion(CTEs) in three crystallographic directions are:αa=(2.57±0.07)×10^-6 K^-1,αb=(8.07±0.13)×10^-6 K^-1,αc=(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(Yb0.25Y0.25Lu0.25Er0.252 SiO5 is controlled on either metal or ceramic substrate.