Structure of tin phosphate glasses by neutron and X-ray diffraction

U. Hoppe, R.K. Brow, A.C. Hannon, M.V. Zimmermann
2019 Journal of Non-Crystalline Solids: X  
A B S T R A C T Neutron and X-ray diffraction experiments with large ranges of scattering vector, up to Q max of 400 nm −1 and 250 nm −1 , respectively, were performed on (SnO) x (P 2 O 5 ) 1-x glasses with 0.5 ≤ x ≤ 0.7, and the structural parameters of the PeO and SneO polyhedra were determined. The fraction of P-NBO (non-bridging oxygen) bonds increases systematically at the expense of the P-BO (bridging oxygen) bonds with SnO additions. The SneO coordination number decreases in a
more » ... way from four at the metaphosphate composition (x = 0.5) to about three at the diphosphate composition (x = 0.67). The structural units are assumed to be SnO 4 trigonal bipyramids and SnO 3 trigonal pyramids with the lone-pair of Sn(II) electrons occupying one of the corners, similar to those in related crystal structures. For all glasses up to x = 0.67, the SnO z pyramids and PO 4 tetrahedra form a continuous network with PeOeP and PeOeSn bonds and the SneO polyhedra do not share oxygen neighbors. From comparisons of the compositional dependences of the SneO and ZneO coordination numbers and the respective number densities of atoms in the binary tin and zinc phosphate glasses, it is presumed that the SneO coordination increases further with N SnO > 4 in the ultraphosphate range (x < 0.5).
doi:10.1016/j.nocx.2019.100017 fatcat:gk5gx6yknjcxxc6al42lmjdpvu