抄録
The molar volume, optical basicity, X-ray fluorescence spectra of Al Kα and X-ray photoelectron spectra of O1s, B1s and Al2p core electrons were measured for alkaline earth aluminoborate (CaBAl and BaBAl) glasses as a function of molar ratio MO/(MO+B2O3)=X (M=Ca and Ba). Inflections and discontinuities in the property vs. X curves, for instance, in compositions containing 20mol% Al2O3 were discussed in terms of formation of [BO4]- and [AlO4]- units and partition of MO to B2O3 and Al2O3. Each of these anomalies was attributed to: the increase in the electron density on bridging oxygens (X=0.25), disappearance of AlO6 units (X=0.35), formation of significant amount of non-bridging oxygen (X=0.40) and decomposition of the BO4 units into O2BO- ones (X=0.44). On this basis, the triclusters were concluded to be absent in the aluminoborate glass network.
