Anin situ hyperconnective network strategy to prepare lanthanum zirconate nanofiber membranes with superior flexibility and toughness

Abstract

Oxide ceramic fibers with softness and toughness are key materials in emerging fields like wearable devices and membrane technologies. However, the brittle failure of oxide ceramic fibers after thermal cycling leads to the loss of membrane architectures, which limits their long-term applications at high temperature. Here, we report a scalable approach of sol–gel electrospinning to synthesize a flexible and tough pyrochlore La_1.85Al_0.15Zr₂O₇ (L5AZO) nanofiber membrane (NFM) involving self-assembled 3D networks. The interactions between the nanoscale constituents lead to the assembled networks with high nodal connectivity and strong crosslinking between nanofibers, which may promote an enhancement of macroscopic mechanical properties by orders of magnitude. Ultrasonic dispersion and an amorphous secondary phase drive the formation of numerous L5AZO nuclei and soft grain boundaries, thus effectively refining grains and inhibiting crystallite growth. Indeed, the L5AZO NFM achieves both a high specific tensile modulus of ∼11.4 MPa cm³ g⁻¹ and fracture toughness of ∼1032 J m⁻², as well as high-temperature resistance above 1100 °C, which are advantageous for diverse structural applications. Furthermore, the simple processing technique of the NFM allows it to be fabricated into various functional devices, such as aerogels, thermal camouflage, and filtration membranes at high temperature. The mechanistic insights and manufacturability provided by this flexible and tough oxide NFM may create further opportunities for materials design and technological innovation.