Borosilicate Glasses

Various anomalous properties of borosilicate glasses are explained by the assumption that the atomic groups, each of which consists of one BO 4 tetrahedron with four BO 3 triangles bonded to it, are formed in these glasses. These atomic groups result from the reasonable postulate that BO 4 tetrahedra cannot be bonded to each other, and that each BO 4 triangle cannot be bonded to more than one BO 4 tetrahedron owing to the disposition of the cation which neutralizes the –1 electronic surplus charge of the BO 4 tetrahedron and prevents these tetrahedra from approaching each other.