Synthesizing Superior Flexible Oxide Perovskite Ceramic Nanofibers by Precisely Controlling Crystal Nucleation and Growth.

Oxide perovskite ceramics are cornerstone materials of electronic devices, but they easily break under bending. Such brittle failure phenomenon limits their applications in emerging flexible electronics. Here, the authors propose a scalable approach of sol-gel electrospinning to synthesize flexible perovskite Li0.35 La0.55 TiO3 (LLTO) nanofibers (NFs) by reducing grain sizes and pore defects in the NFs. The strategy is to precisely control crystal nucleation and growth by forming homogeneous nuclei in the sol before electrospinning and to construct soft twin and amorphous grain boundaries by controlling calcination temperatures. Ball-milling the sol promotes the formation of numerous LLTO nuclei and thus effectively refines grains, while using gradient calcination temperatures from 200 to 900 °C creates intricate soft grain boundaries. The individual LLTO NF shows ceramic toughness with an elastic modulus of ≈40 GPa and the NF film demonstrates silk-like softness with a large elastic strain of 1.51%. Moreover, the LLTO film shows superior fatigue resistance and it maintains structure well after repeated tensile-buckling cycles at 40% strain. The proposed strategy facilitates to develop flexible oxide perovskite ceramic films with appealing applications.