Our approach begins with the synthesis of silica hollow nanotubes using a reverse micelle microemulsion technique. Nickel hydrazine complexes form anisotropic crystalline templates within Brij-stabilized inverse micelles, enabling controlled growth of high-aspect-ratio nanorods. These templates are then coated with silica via hydrolysis of tetraethyl orthosilicate (TEOS) and etched with HCl to yield pure amorphous silica nanotubes. Dimension control is achieved by tuning surfactant molecular weight and nickel ion concentration. Multiple etching steps and ICP-MS analysis confirm near-complete removal of nickel, producing clean, grain-free nanostructures suitable for optical applications.
To form stable colloidal suspensions, the silica nanotubes are functionalized with PEG-silanes, promoting dispersion in water and the formation of lyotropic nematic phases. Under these conditions, blade-coating yields highly aligned, birefringent thin films with continuous monodomain textures, as confirmed by optical microscopy and electron imaging. These films exhibit form birefringence and represent a new class of mesomorphic ceramics—materials that derive long-range orientational order from liquid crystalline suspensions but achieve optical and mechanical properties via post-processing into solid ceramics.
Current work focuses on optimizing drying protocols and sintering conditions to mitigate cracking and improve optical quality. The resulting films show potential as large-aperture, high-LIDT waveplates for demanding laser environments. This scalable route—combining nanomaterial synthesis, lyotropic self-assembly, and shear alignment—opens new possibilities for the fabrication of functional optical ceramics.