Abstract:

High-entropy ceramics (HECs) show outstanding properties such as amorphous-like thermal conductivities, colossal dielectric constant, superionic conductivity, enhanced electromagnetic wave absorption ability, super hardness and strength, which are promising for structural and functional applications. However, the high synthesis temperature has become the bottleneck that hinders the scale-up production and practical applications of HECs. It is thus appealing to develop a novel low-temperature process for the synthesis of HECs. To demonstrate the feasibility of low-temperature synthesis, herein, an electrospinning method has been utilized, for the first time, for the synthesis of high-entropy (Y_0.2Yb_0.2Sm_0.2Eu_0.2Er_0.2)₂O₃ nanofibers. It has been found that after electrospinning from liquid precursors single phase (Y_0.2Yb_0.2Sm_0.2Eu_0.2Er_0.2)₂O₃ solid solution with bixbyite structure can be formed by calcining at a temperature as low as 500 °C, which is at least about 1000 °C lower than that used in the solid-state synthesis method. The as-prepared (Y_0.2Yb_0.2Sm_0.2Eu_0.2Er_0.2)₂O₃ nanofibers are continuous and uniform with a smooth surface and a small diameter of 150 nm. It is also intriguing that the average grain size of (Y_0.2Yb_0.2Sm_0.2Eu_0.2Er_0.2)₂O₃ is only about 10 nm, which is much smaller than that in the solid-state synthesized powders. In addition, all the elements are homogeneously distributed along the nanofibers. This work demonstrates that high-entropy ceramic nanofibers can be synthesized from liquid precursors at low temperatures through a simple, efficient, and low-cost electrospinning method, which opens up a new avenue for the low-temperature synthesis of HECs.

Key words: High-entropy ceramics, Nanofibers, Electrospinning, Rare earth metal oxides, Synthesis