Single-Phase, Large Plastic Deformation, and Highly Flexible Yb₂O₃ Nanofibrous Membranes for Thermal Insulation

Ultralow-density (35–60 mg·cm –3 ) Yb 2 O 3 nanofibrous membranes (YbFMs) with a multilayer structure were successfully prepared for the first time using Yb-acetylacetone coordination polymer as a precursor. Thanks to the high ceramic yield (62.1%) and excellent spinnability of the precursor, the YbFMs exhibited outstanding flexibility, which does not cause damage even when bent or knotted. The tensile strength of the YbFMs was 1.69 MPa, and the maximum elongation could reach 33%. Notably, the YbFMs exhibited robust fatigue resistance, retaining 87.2% of the initial stress even after 500 buckling cycles and preserving 84.75% of the initial stress in compression resilience. Moreover, the YbFMs exhibited flexibility and compressive performance in the temperature range of −196–1350 °C. The thermal conductivity of the YbFMs was 28.9–34.6 mW·m –1 ·K –1 . At a hot surface temperature of 1350 °C, the 6 mm thick YbFMs could reduce the back temperature by about 1070 °C. Thus, YbFMs are expected to be a flexible insulation material at extremely high temperatures.