Ftir and dta study of lanthanum aluminosilicate glasses

Abstract Structure and glass transition temperature of lanthanum aluminosilicate (LAS) glasses, containing: (15–25) mol% La2O3, (15–35) mol% A12O3 and (40–70) mol% SiO2, were studied by FTIR spectroscopy and differential thermal analysis. The effects of La2O3 and A12O3 on the properties and structures of LAS glasses were evaluated. The Al+3 ion can assume both four-fold co-ordination, forming (AlO4/2)− tetrahedra, and six-fold co-ordination forming (AlO6/2)−3 octahedra. The amount of these depends on La+3 content; acting as network modifier, it can compensate the charge of three neighbouring (AlO4/2)−units or one (AlO6/2)−3 unit.