Thermophysical performances of novel high entropy (La0.25RE0.25Yb0.25Y0.25)2Ce2O7 (RE=Nd and Dy) oxides

Two novel high-entropy ceramics, (La0.25Nd0.25Yb0.25Y0.25)(2)Ce2O7 and (La0.25Dy0.25Yb0.25Y0.25)(2)Ce2O7, were synthesized via a sol-gel technique and sintering at high temperatures. The lattice type, micro-morphology, thermophysical performances and lattice stability of these two high-entropy ceramics were investigated. The results exhibit that the obtained bulk samples have single fluorite lattice, dense microstructure, and uniform element distribution. Owing to the high-entropy influence, the high-entropy oxides exhibit lower thermal conductivities than 7YSZ, and the thermal conductivity of (La0.25Dy0.25Yb0.25Y0.25)(2)Ce2O7 is lower than that of (La0.25Nd0.25Yb0.25Y0.25)(2)Ce2O7. Because of the less ionic size of Dy3+ than that of Nd3+, the thermal expansion coefficient of (La0.25Nd0.25Yb0.25Y0.25)(2)Ce2O7 is higher than that of (La0.25Dy0.25Yb0.25Y0.25)(2)Ce2O7. Their thermal expansion coefficients are higher than that of 7YSZ, and these two novel high-entropy oxides also exhibit outstanding lattice stability up to 1200 degrees C.

Automated summary

Two novel high-entropy ceramics, (La0.25Nd0.25Yb0.25Y0.25)(2)Ce2O7 and (La0.25Dy0.25Yb0.25Y0.25)(2)Ce2O7, were synthesized via a sol-gel technique and sintering at high temperatures. The obtained samples exhibit single fluorite lattice, dense microstructure, and uniform element distribution. Due to the high-entropy influence, the ceramics have lower thermal conductivities and higher thermal expansion coefficients compared to 7YSZ, while maintaining outstanding lattice stability at high temperatures.