Preparation and IR Characterization of Li_2O-B_2O_3-Al_2O_3 Composite Xerogel

Li2O-B2O3-Al2O3 composite xerogels were successfully prepared from lithium methoxide,tri-nbutylborate and aluminum tri-sec-butoxide dissolved in methanol and tetrahydrofuran by Sol-Gel method.The structure changes of xerogels upon increasing the Al2O3 content and thermal treatment temperatures from 150℃ to 550℃ were characterized by FTIR and XRD.The results indicate that the relative content of BO4 units shows a continuous decrease with increasing Al2O3 contents.Consequently,the concentration of asymmetric BO3 units increase.The relative content of symmetric BO3 units decrease.Total relative content of BO3 units increase with the Al2O3 content increasing.The structure of the xerogel containing 10 mol%Al2O3 after heat-treatment at 550℃ for 1h transforms from glassy to crystalline.The main crystalline is Li2AlB5O10.