It is generally accepted that. fused BZ03 is composed of B0 3 triangles. These triangles are joined togetner randomly, forming l the glass network. I.R. studies and x-ray diffraction studies on pure BZ03 glass indicated clearly that these triangles are joined together forming boroxole groups. These groups are joined together forming the random network. It is also accepted that addition of alkali oxides to boron oxide results in a glassy network in

If an ion in a crystal is replaced by an impurity ion with a different charge, compensation for the charge difference must be accomplished. This is usually done by an intrinsic defect, i. e. a lattice vacancy or interstitial host ion, in such a way to balance the excess or deficit of charge. The introduction of cation vacan cies along with divalent cation impurities in alkali halides is a familiar example. If these crystals are carefully annealed, nearly all of the compensating defects migrate to the impurity ions to form impurity-defect complexes. It is the behavior of these complexes that...