Structural specifics of phosphate glasses probed by diffraction methods: a review

Structure of GeO2–P2O5glasses studied by x-ray and neutron diffraction

“…According to equation (2) two PO 4 tetrahedra provide the GeO 6 unit with two additional electrons. This consideration implies that the single P−O bonds in the bridges with the [6] Ge and [4] Ge sites should possess lengths close to those known of P−O B bonds (~0.160 nm [28,38]). However, due to the high positive charge at the P 5+ ion, part of the negative charge formally given to the GeO 6 retains closer to the P 5+ .…”

The structure of phosphate glass evidenced by small angle X-ray scattering

“…4 indicate the presence of two differently-sized heterogeneities of electron density in the samples. According to (3) and (4), from the slope of the straight lines in Fig. 4 the radius of sphere, R, of the small-scale heterogeneities was obtained to be about 1 nm for the glasses with the molar ratios y = 0.99, 1.17 and 2.27.…”

“…The length scale of these sequences correlates with the distances of the P-P pairs (ffi0.7 nm). As extracted from diffraction experiments by using reverse Monte Carlo simulations [3,34] these distances dominantly contributes to the formation of the prepeak, but there are also some contributions of Sr-Sr distances to this peak.…”

“…Incorporating a metal oxide into the PO 4 network depolymerizes the network structure by converting O B atoms to non-bridging oxygen (O NB ) atoms by breaking the P-O-P links, which produces Q 2 groups. In the ultraphosphate region both units Q 3 A great deal of new information on the short and intermediate range structure of phosphate glasses has been extracted by means of diffraction methods. The more recent diffraction studies of phosphate glasses, particularly those published since 1990, were reviewed by Hoppe et al [3].…”

“…In the ultraphosphate region both units Q 3 A great deal of new information on the short and intermediate range structure of phosphate glasses has been extracted by means of diffraction methods. The more recent diffraction studies of phosphate glasses, particularly those published since 1990, were reviewed by Hoppe et al [3]. The investigations have been directed to the shortrange order ($0.15-0.3 nm) by using wide angle scattering with X-rays and neutrons, that permits coordination numbers and next neighbor distances of atoms to be determined.…”