2002 Volume 13 Pages 131-136
The transitional point in phosphate glasses between a surfeit of terminal oxygen atoms and a situation where modifier ions share oxygen neighbors in their coordination polyhedra depends on the valency and dimension of the Me added. For polyphosphate glasses with the small Ga3+ cations the transition is still not at-tained (decrease of NGao) while for the glasses with Y, Mg, Zn with constant NMeO the transition is already passed and a clustering of the oxygen polyhedra of the Me atoms ensues. X-ray and neutron diffraction are used to extract Me-O coordination numbers of the bi- and three-valent Me atoms in polyphosphate glasses.
