High-entropy(La_(0.2)Nd_(0.2)Sm_(0.2)Gd_(0.2)Yb_(0.2))_(2)(Zr_(0.75)Ce_(0.25))_(2)O_(7)thermal barrier coating material with significantly enhanced fracture toughness

Poor fracture toughness leads to premature failure of La_(2)(Zr_(0.75)Ce_(0.25))_(2)O_(7)(LCZ)ther-mal barrier coatings in an elevated temperature service environment.A novel coating material,namely(La_(0.2)Nd_(0.2)Sm_(0.2)Gd_(0.2)Yb_(0.2))_(2)(Zr_(0.75)Ce_(0.25))_(2)O_(7)(LNSGY)based on the high-entropy con-cept,was successfully fabricated by solid-state sintering.The microstructure of LCZ and LNSGY was investigated by X-Ray Diffraction(XRD),Raman Spectrometer(RS),Transmission Electronic Microscopy(TEM)and Scanning Electron Microscopy(SEM).The fracture toughness of the LCZ and LNSGY ceramics was evaluated.The LNSGY has excellent high-temperature phase stability,and the grain size of LNSGY ceramic is smaller than that of LCZ ceramic at an elevated temper-ature due to the sluggish diffusion effect.Compared with LCZ(fracture toughness is(1.4±0.1)MPa·m^(1/2)),the fracture toughness of LNSGY is significantly enhanced(fracture toughness is(2.0±0.3)MPa·m^(1/2)).Therefore,the LNSGY can be a promising advanced thermal barrier coat-ing material in the future.