Structure of various phosphate and borate glasses by X-ray diffraction with high-energy photons U. Hoppe, R.K. Brow 1 , L. Ghussn 1 , M. Müller 2 , C. Rüssel 2 , and M. von Zimmermann 3 Institut für Physik Universität Rostock, Universitätsplatz 3, 18051 Rostock, Germany 1 Dept. Materials Science and Engineering Missouri University of Science and Technology, Rolla MO 65409, U.S.A. 2 Otto-Schott-Insitut für Glaschemie Friedrich-Schiller-Universität Jena, Fraunhoferstr. 6, 07743 Jena, Germany 3 DESY Photon Science, Notkestraße 85, 22607 Hamburg, Germany Diffraction experiments with hard X-rays that were available at the BW5 instrument of DORIS III revealed to be a powerful tool for clarifying the short-range structures of a great variety of oxide glasses. The beamtime in October 2013 just before the final shutdown of DORIS III was the last chance to collect high-quality scattering data for calculation of X-ray structure factors S(Q) of disordered matter systems. Three short series of glassy samples were chosen for our last two days. The first series includes ZrO 2 -Li 2 O-B 2 O 3 glasses. They complete the research on another series of Zr silicate glasses that was measured before. The Li 2 O content was reduced with the ZrO 2 additions to maintain a constant [B]/[O] ratio. This ratio is expected to determine the [BO 4 ]/[BO 3 +BO 4 ] ratio which we like to hold constant while the [Zr]/[Li] ratio is changed. Our interest concerns possible changes of the Zr-O and Zr-Zr correlations with increasing Zr content. The results will be analysed and interpreted together with Zr-K-edge EXAFS experiments on the same charges of samples. The second series belongs to the Al 2 O 3 -SiO 2 -P 2 O 5 system. Such samples are difficult for diffraction experiments. The three glass-forming oxides can form a variety of different oxygen polyhedra. But the central Al, Si or P atoms possess similar shape and scattering power and one cannot differ- entiate their sites. Moreover, 27 Al, 29 Si and 31 P NMR experiments are excellent for determination of the oxygen polyhedra and, possibly, also the preferred second neighbours [1]. Thus, NMR is a much better probe. Here, three samples were measured which possess compositions a little different than those used in Ref. [1]. The P 2 O 5 content is comparably high. The fractions of the three oxides were varied to allow the Si and Al sites to form octahedral environments only. All Si or Al form SiO 6 or AlO 6 environments in the related crystal structures SiP 2 O 7 and AlP 3 O 9 , respectively. Glasses of AlP 3 O 9 compositions possess six-coordinated Al sites. The behaviour of the Si sites in glasses is unknown. SiO 6 octahedra were found in Na/Si-phosphate glasses. The similar GeO 2 -P 2 O 5 glasses 0 50 100 150 200 250 300 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Al 2 O 3 -SiO 2 -P 2 O 5 system Neutron diffraction X-ray diffraction AlSiP 5 O 16 SiP 2 O 7 Al(PO 3 ) 3 Structure factor, S(Q) Momentum transfer, Q /nm -1 Figure 1: X-ray and neutron structure factors of three Al/Si-phosphate glasses. The glass compositions used should force a maximum formation of six-coordinated Al and Si atoms.