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 ((La_0.25Nd_0.25Sm_0.25Gd_0.25)_0.75Yb_0.25)₂Zr₂O₇. 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°C, while fibers with the pyrochlore structure and the diameter within 140 nm were obtained by calcining at temperature higher than 1100°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°C). These promising properties indicate that the HEC fibers could be candidate materials for thermal-insulation application.