Structure determination of low-alkali-content Na₂S + B ₂S₃ glasses using neutron and synchrotron X-ray diffraction

The structures of low-alkali-content xNa₂S + (1 - x)B ₂S₃ (x ≤ 0.2) glasses have been studied by neutron and synchrotron X-ray diffraction. Similar results were obtained both in neutron and synchrotron X-ray diffraction experiments. One significant difference, however, is that with the higher resolution obtainable in the X-ray atomic distribution function data, the peak at 1.8 Å splits into two components, one at 1.8 Å and one at 1.93 Å with the addition of Na₂S to B₂S₃. The experimental total atomic distribution functions have been compared to model ones computed on the basis of structure data for crystalline counterparts of the glasses. The results provide direct structural evidence that doping B₂S₃ with Na₂S creates a large fraction of tetrahedrally coordinated borons in the glass.