Crystallization control of SrCO3 nanostructure in imidazolium-based temperature ionic liquids

Strontium carbonate nanostructures, with unique nanowhisker, nanospindle, nanosphere, sphere, spindle, and rodlike hierarchical structure, were synthesized in imidazolium-based room temperature ionic liquids [C4mim]PF6, [C4mim]Cl, [C8mim]Br, [C8mim]BF4, and [HOEtMIm]NTf2. The nanostructures were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis. The results show that the morphologies of SrCO3 were strongly dependent on the nature of the corresponding RILs, its content, and the reaction temperature. RILs can act as structure-directing agent, leading the auto-assembly of SrCO3 crystal. [C8mim]BF4 and [HOEtMIm]NTf2 favored the production of nanowhisker and nanospindle SrCO3, respectively, whereas [C4mim]PF6 favored the production of nanosphere. Small particles were obtained at high reaction temperature. Low starting decomposition temperature was observed. Finally, the formation mechanism of the SrCO3 crystal was preliminary presented.