Ceramics-Silikáty 39 (1) 20-29 (1995)

INFRARED SPECTRA OF GLASSES IN THE l5 Na₂O.10 (MgO, CaO, TiO₂, ZrO₂).75 SiO₂ SYSTEM

M. Liška, H. Hulínová, P. Šimurka, J. Antalík

The shape of infrared spectra measured by KBr pellet technique is characterized by very strong asymmetric peak with maximum at 996-1072 cm^-1 medium peak at 774-786 cm^-1 and strong absorbance peak at 447-466 cm^-1. The maxima positions of the first and the third absorption peaks correlate linearly with the NBO/T ratio (i.e. non-bridging oxygen to tetrahedral central atom molar ratio), which depends on the presupposed value of the network-forming fraction of Ti atoms a₄(Ti). The correlation coefficient reaches maximal value for a₄(Ti)=0.15 for the first peak and for a₄(Ti)=0.25 for the third peak, confirming such way the partial network-forming activity of Ti02. The spectral shape is explained by the superposition of Q⁴(Si0₂; 3-dimensional), Q³(Si₂O₅; sheet) and Q²(SiO₃; chain) structural units. The spectra of Q⁴ and Q³ units obtained from measured spectra by linear regression analysis are in qualitative agreement with the results of numerical FG simulation of Furukawa et al.