Publikace detail

Medium range order in lead borophosphate glasses

Autoři: Koudelka Ladislav | Mošner Petr | Zeyer Michaela | Jäger Christian

Rok: 2005

Druh publikace: článek ve sborníku

Název zdroje: 5th International Conference on Borate Glass

Název nakladatele: University of Trento

Místo vydání: Trento

Strana od-do: 26

Tituly:

Jazyk	Název	Abstrakt	Klíčová slova
cze	Uspořádání středního dosahu v olovnatých borofosfátových sklech	Byla studována 11B MQMAS NMR spektra olovnatých borofosfátových skel v kompoziční řadě 50PbO-xB2O3(50-x)P2O5 (x = 15, 20 a 25 mol%B2O3).
eng	Medium range order in lead borophosphate glasses	Borophosphate glasses offer for structural studies two NMR active nuclei ? 31P and 11B. Our previous study of 11B MAS NMR spectra of lead borophosphate glasses of the series 50PbO-xB2O3-(50-x)P2O5 showed that within the composition range of x = 0-15 mol.% B2O3 boron forms exclusively BO4 groups, whereas in the region x = 15-25 mol% B2O3 NMR spectra showed also on the increasing presence of BO3 groups. Moreover, within the region x = 15-25 mol%B2O3 NMR signal is composed of two lines, the origin of which was not studied yet. In this study we investigated 11B MQMAS NMR spectra of the 50PbO-xB2O3(50-x)P2O5 glasses with x = 15, 20 and 25 mol%B2O3 to elucidate the character of two BO4 sites in these glasses. The first site B(1), characterized by the chemical shift in the glass with x = 15, is the only present boron site within the composition region of x = 0-15 mol% B2O3. We ascribed these sites to tetrahedral B(OP)4 structural units. In the glasses within the composition x = 15-25 mol% B2O3 the site B(1) is gradually replaced by the second site B(2) with the chemical shift in the glass with x = 25. This site we assigned to the presence of B(OP)3(OBO2) units, where boron atom is linked to three neighbor PO4 groups and to one BO3 group. The correlation of these results with 31P MAS NMR spectra and Raman spectra is discussed.	borophosphate glasses, lead, structure, NMR

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