Isomorphic Substitutions in the System SrO-BaO-Al2O3-TiO2-SiO2.

In the system SrO-BaO-Al//2O//3-TiO//2-SiO//2 in samples with a larger, concentration of SiO than of BaO or in samples with equal concentrations of the two solid solutions based on triclinic strontium anorthite are formed, while in samples with a higher content of BaO solid solutions based on nonclinic celsian are formed. The homogeneity region in the celsian form BaAl//2Si//2O//8 is relatively narrower than in SrAl//2Si//2O//8. The isomorphism in the system SrO-BaO-Al//2O//3-TiO//2-SiO//2 is greatly affected by the Al//2O//3/(SrO plus BaO) ratio. In the investigated glasses an increase in this ratio from 0. 5 to 1. 25 reduces the temperature of the start of formation of solid solutions from 1470 to 1220 K.