Controlling the growth of zirconia needles precursor from a liquid crystal template

Abstract: This work reports the directional growth of macroscopic ceramic needles by combining a thermo-responsive sulfated hydroxy zirconyl (SHZ) hydrosol with a swollen hexagonal liquid crystal (SHLC). The effect of the molar ratio R s =[Zr4+]/[SO4 2−] on the thermo-stability of both the SHZ hydrosol and the SHLC, and also on the nucleation and 1D-growth of ceramic particles was investigated. The dynamics of the thermo-induced aggregation growth process was monitored in situ by rheological property measurements. The results show that by increasing the R s, the kinetic stability of the system in the sol state increases, leading to the formation of a less branched framework during the thermo-induced aggregation process. Furthermore, the small-angle X-ray diffraction (XRD) results show that the thermo-stability of the SHLC employed as soft template is improved by increasing the R s. Both effects allow us to induce the particle''s nucleation by heating the SHLC template to a moderate temperature (≈50°C), while the kinetics of the needle''s growth is enhanced by increasing the [Zr4+]/[SO4 2−] molar ratio. [Copyright &y& Elsevier]