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 Li2SiO3 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. -- Graphical abstract: Li2SiO3 was synthesized using a hydrothermal process in the presence of different surfactants. Li2SiO3 powders were composed of uniform micrometric particles with a hollow sphere morphology and nanostructured walls. Display Omitted Highlights: → Pure Li2SiO3 was synthesized by the hydrothermal method. → Surfactant addition produced microstructural and morphological variations. → TEM reveled the generation of nanostructured hollow spheres.