Spectroscopic Analysis of the Structure of Silicate Glasses along the Joint xMAlO2-(1–x)SiO2(M = Li, Na, K, Rb, Cs)

Infrared spectroscopic studies of charge-coupled substitution in silicate glasses and crystals along the joints x MAlO₂(1 – x )SiO₂ (M = Li, Na, K, Rb, and Cs; 0.10 ≤ x ≤ 0.60) were carried out in the range 2000 to 200 cm⁻¹ Three major absorption bands appeared in the 1100-, 800-, and 500-cm⁻¹ regions. For a specific value of x, the observed changes in frequency, intensity, and bandwidth decreased in the order Li > Na > K > Rb > Cs and the apparent disorder in the glass structure caused by the substituted aluminum increased in the direction K < Na < Li. The 800-cm⁻¹ band splits at SiO₂≃ 0.75 mol, which has been interpreted in terms of the number of AlO₄ tetrahedra in the structure. Most of the substituted aluminum in the glasses and the crystals was found to be in the fourfold coordination.