Synthesis of ultra‐fine rare‐earth‐zirconate high‐entropy ceramic fibers via electrospinning

Ceramic fibers have the advantages of low density, high strength, high temperature resistance, and excellent mechanical vibration resistance. In this work, sol-gel and electrospinning were used to prepare ultra-fine rare-earth-zirconate high-entropy ceramic (HEC) fibers with the composition of ((La0.25Nd0.25Sm0.25Gd0.25)(0.75)Yb-0.25)(2)Zr2O7. The decomposition process and microscopic morphology of the fibers were characterized by thermogravimetry/differential scanning calorimetry, Fourier transform infrared and scanning electron microscope. The results indicated that defective fluorite-structured fibers with a smooth surface were obtained by calcining at 900-1000 degrees C, while fibers with the pyrochlore structure and the diameter within 140 nm were obtained by calcining at temperature higher than 1100 degrees C. The HEC fibers still maintain a continuous microstructure on the surface after calcination. In addition, the porous ceramics prepared from HEC fibers have a comparatively low thermal conductivity (0.22 +/- 0.05 W m(-1) K-1, 25 degrees C). These promising properties indicate that the HEC fibers could be candidate materials for thermal-insulation application.