THE EFFECT OF TI4-AL2O3-SIO2-TIO2 SYSTEM GLASS( ON THE SITE OF AL3+ IN THE STRUCTURE OF CAO)

The structures of 20CaO . 17Al(2)O(3). 63SiO(2), 20CaO . 17Al(2)O(3). 63SiO(2). 4.5TiO(2), and 20CaO . 17Al(2)O(3). 63SiO(2). 9TiO(2) glasse s are investigated by the methods of Si-29-, and Al-27-MAS-NMR spectra , A12p X-ray photoelectron spectroscopy and Raman spectra. The network of 20CaO . 17Al(2)O(3). 63SiO(2) glass consists mainly of Q(3) and Q( 4) groups and some Al3+ ions enter as the network formers in the form of [AlO4]Ca[AlO4] as well as [AlO4]CaO- and other Al3+ ions still stay as the network modifiers. When 4.5 mol.% TiO2 are added to this glass , the Ti4+ ions enter as the network formers in the form of [TiO4] and have no ;obvious effect on the site of Al3+. With 9 mol.% TiO2, the g lass network consists mainly of Q(2), Q(3), and Q(4) groups. The Ti4ions enter as the network formers and take the place of some Al3+ ions in the network, and some additional non-bridging oxygen ions correspo nding to the above replaced Al3+ ions are formed, that introduces the Q(2) groups and decreases the aggregation extent of glass network. Thi s is also certificated by the differential thermal analysis (DTA). (C) 1998 Elsevier Science S.A. All rights reserved.