Preparation and characterization of mesoporous lithium borosilicate material via the sol–gel process

The lithium borosilicate gels were prepared from the cohydrolysis of the tetraehtylorthosilicate (Si(C₂H₅O)₄) and triethylborate (B(C₂H₅O)₃) by using an ethanolic solution of tetradecyltrimethylammonium bromide (TTAB) as surfactant. The Li⁺ ions were introduced from an acidic solution of lithium carbonate (Li₂CO₃). Depending on the B/Si, Li/Si and TTAB/Si molar ratios at pH equal to 1 and at room temperature, monolithic and transparent colourless gels were obtained. The structure of the gel was investigated by infrared spectroscopy (IR), ²⁹Si, ¹¹B and ⁷Li solid-state magnetic resonance (MAS NMR) and by thermal analysis (DTA–TG). The results show the possibility of obtaining a borosilicate network via B–O–Si bonds in which Li⁺ ions were dispersed. The adsorption–desorption isotherms of the xerogel were characteristic of mesoporous materials. These materials may provide a greater free volume through which conducting ions can move.