Cost-effective, facile, and scalable synthesis of alumina ceramic nanowires through strain-induced conversion of Al-Li bimetallic alloys

Abstract

One-dimensional (1D) Al₂O₃ materials with high aspect ratios are highly desirable because they promise to be functional and structural blocks for a new generation of nanocomposites due to their unique mechanical and chemical properties. Unfortunately, producing 1D Al₂O₃ microstructures at a large scale always suffers from costly or toxic chemicals and their complicated synthesis procedures. The present study proposed a straightforward strategy based on the strain-induced transformation of porous Al-Li bulk into 1-D nanowires (NWs), which enable scalable and low-cost producing batches of Al₂O₃ NWs. The balance between the minimization of strain energy of the reaction front and surface energy of in-situ formed NWs dominates the overall transformation process. We show that the surface activity of porous Al was significantly stimulated through the dissolution of Li⁺ ion as immersed the pristine Al-Li alloy in deionized water, and resulting Li-doped porous Al preform gradually evolved and transformed into Al ethoxide NWs in time of a dealloying reaction in ethanol. Such NWs can be eventually converted into pure Al₂O₃ NWs after subsequent annealing in air. We investigate the evolution process of NWs and the effect of Al−Li alloy composition, and thermal treatment temperature on the crystallographic structure and morphology of the obtained Al₂O₃ NWs. The newly developed Al₂O₃ nanowires obtained without using any co-catalyst, doping agents, or any other complexity of the procedure are expected to be of interest in industrial-scale applications.