Thermophysical Properties Tuning for (Y 0.25 La 0.25 Nd 0.25 Eu 0.25 ) 2 Zr 2 O 7 via Controlled B‐site Ti 4+ Substitution

ABSTRACT A novel series of high‐entropy ceramics (Y 0.25 La 0.25 Nd 0.25 Eu 0.25 ) 2 (Zr 1‐ x Ti x ) 2 O 7 ( x = 0, 0.25, and 0.5) was synthesized via solid‐state reaction. The results indicated that the doping of Ti 4+ partially substituted the site of Zr 4+ , induced lattice distortion, and tuned thermophysical properties. The thermal conductivity at 25°C reaches its minimum value of 1.233 W·m −1 ·K −1 at x = 0.25, representing a 15% reduction compared to the undoped sample, while maintaining a coefficient of thermal expansion near 10.30 × 10 −6 K −1 . Notably, under the combined effects of grain refinement and stress concentration, the fracture toughness of (Y 0.25 La 0.25 Nd 0.25 Eu 0.25 ) 2 (Zr 1‐ x Ti x ) 2 O 7 ( x = 0.25) increases to the value of 1.746 MPa·m 1/2 , while the elastic modulus decreases to 79.42 GPa. This work demonstrates that the design of B‐site doping can effectively improve the thermophysical properties of rare‐earth zirconates, making these ceramics promising candidates for next‐generation thermal barrier coatings.