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

Abstract (30 −  x /2)Li 2 O·(70 −  x /2)B 2 O 3 · x Al 2 O 3 ( x  = 0, 5 and 10) composite gels have been fabricated by the sol–gel method. LiOCH 3 , B(OC 4 H 9 ) 3 , and Al(OC 4 H 9 ) 3 were used as precursor for Li 2 O, B 2 O 3 , and Al 2 O 3 , respectively. B(OC 4 H 9 ) 3 and Al(OC 4 H 9 ) 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.