Surfactant-assisted hydrothermal crystallization of nanostructured lithium metasilicate (Li₂SiO₃) hollow spheres: (I) Synthesis, structural and microstructural characterization

Lithium metasilicate (Li₂SiO₃) was successfully synthesized using a hydrothermal process in the presence of different surfactants with cationic, non-ionic and anionic characters. The samples obtained were compared to a sample prepared by the conventional solid-state reaction method. The structural and microstructural characterizations of different Li₂SiO₃ powders were performed using various techniques. Diffraction analyses revealed the successful crystallization of pure Li₂SiO₃ single phase by hydrothermal technique, even without further heat-treatments and independent of the surfactant used. Electron microscopy analyses revealed that Li₂SiO₃ powders were composed of uniform micrometric particles with a hollow sphere morphology and nanostructured walls. Finally, different thermal analyses showed that Li ₂SiO₃ samples preserved their structure and microstructure after further thermal treatments. Specific aspects regarding the formation mechanism of the spherical aggregates under hydrothermal conditions are discussed, and there is a special emphasis on the effect of the synthesis pathway on the morphological characteristics.