Rare‐Earth Zirconate Ceramics with Fluorite Structure for Thermal Barrier Coatings

A series of rare‐earth zirconate Ln 2 Zr 2 O 7 ceramics (Ln=Dy, Er, and Yb) with a fluorite structure (F‐Ln 2 Zr 2 O 7 ) were prepared by pressureless sintering from zirconia and rare‐earth oxide powders at 1600°C for 10 h in air. The microstructure experiments were performed by X‐ray diffractometry (XRD) and scanning electron microscopy (SEM). The thermal conductivity and thermal expansion of these ceramics were evaluated using a steady‐state laser heat‐flux technique and high‐temperature dilatometry, respectively. The XRD and SEM results demonstrate that Ln 2 Zr 2 O 7 ceramics with a single fluorite phase are synthesized and no other phases are found. The results of thermal conductivity show that their thermal conductivities (1.3–1.9 W/(m·K), 20°–800°C) are as low as those of the referenced Ln 2 Zr 2 O 7 ceramics (Ln=La, Nd, Sm, and Gd) with pyrochlore structure (P‐Ln 2 Zr 2 O 7 ). It is concluded that rare‐earth zirconate ceramics with a fluorite structure can be considered as candidate materials for future thermal barrier coatings.