Devitrification behavior and structure of Li2O–B2O3–Al2O3 composite gels from metal alkoxides

(30 − x/2)Li2O·(70 − x/2)B2O3·xAl2O3(x = 0, 5 and 10) composite gels have been fabricated by the sol–gel method. LiOCH3, B(OC4H9)3, and Al(OC4H9)3 were used as precursor for Li2O, B2O3, and Al2O3, respectively. B(OC4H9)3 and Al(OC4H9)3 were hydrolyzed separately and then mixed. The crystallization behavior and structure of the gels upon thermal treatment temperatures between 150 and 550 °C are characterized on the basis of SEM, XRD and IR analyses. Xerogel with x = 0 exhibits non-crystal features, whereas crystalline phases are found in the xerogels with x = 5 and 10. The crystalline phases are not found with increasing heat treatment temperatures from 150 to 450 °C, but crystalline phases appear present at 550 °C. The xerogel with x = 0, subject to thermal treatment below 450 °C, is found to be still amorphous, and a 550 °C heat treatment leads its structure changing from glassy to crystalline.