Structure of binary antimony phosphate glasses by diffraction methods

Antimony phosphate glasses (Sb2O3)x(P2O5)(1-x) with x = 0.05 and 0.80 were measured by neutron and X-ray diffraction with high real-space resolution. The P -O and O -O distance peaks of the PO4 tetrahedra were found with the expected parameters. For the glass of x = 0.80 the Sb- O and O -O coordination numbers and distances suggest highly distorted SbO3 and SbO4 environments according to strong lone-pair effects of the Sb3+. The fraction of SbO(4 )has the right portion that all oxygens can form Sb-O-Sb or Sb-O-P bridges. Significant numbers of secondary Sb- O bonds (> 0.25 nm) are extracted. The first diffraction peak at 13 nm-1 is related to distances between stacked layers of corner-connected oxygen triangles as in the orthorhombic Sb2O3. For the glass of x = 0.05 the medium-range order reminds that of vitreous P2O5. Its SbO4 units are formed with mean Sb- O bonds of 0.210 nm.