TY - JOUR A1 - Zeyer, M. A1 - Montagne, L. A1 - Kostoj, V. A1 - Palavit, G. A1 - Prochnow, D. A1 - Jäger, Christian T1 - 17O nuclear magnetic resonance study of Na2O-P2O5 glasses N2 - The preparation and structural investigation of 17O-enriched xNa2O–(100-x)P2O5 glasses (46.5<=x<=62.8) by nuclear magnetic resonance (NMR) is described. Enriched phosphoric acid was prepared by hydrolysis of PCl5 with 17O-enriched water and neutralized with sodium carbonate. The sodium metaphosphate was then melted at 800 °C for 15 h and quenched. Polyphosphate and ultraphosphate glass compositions were prepared by remelting the metaphosphate with sodium carbonate and phosphorus pentoxide, respectively. 31P magic angle sample spinning (MAS) NMR was used to determine the Na2O/P2O5 content in the glasses. 17O NMR spectra (quadrupole echo for non-rotating samples and multiple-quantum excitation for rotating samples (MQMAS)) show two oxygen sites in the samples with large quadrupolar coupling constants (4.7 and 7.7 MHz), in accordance with the high phosphorus electronegativity. According to the correlation of 17O quadrupolar constants with bond ionicity, these two components are attributed to bridging P–O–P and non-bridging P–O...Na oxygens. The average P–O–P bond angle is estimated with the quadrupolar asymmetry derived from the fit of the static echo spectra. The MQMAS spectrum shows a distribution of non-bridging oxygen chemical shifts, attributed to a variation of bond length and angle. PY - 2002 SN - 0022-3093 VL - 311 IS - 3 SP - 223 EP - 232 PB - North-Holland Publ. Co. CY - Amsterdam AN - OPUS4-11013 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zeyer-Düsterer, Michaela A1 - Montagne, L. A1 - Palavit, G. A1 - Jäger, Christian T1 - Combined 17O NMR and 11B-31P double resonance NMR studies of sodium borophosphate glasses N2 - 17O enriched sodium borophosphate glasses were prepared from isotopically enriched NaPO3 and H3BO3. These glasses have been studied by 17O, 11B and 31P NMR including 17O and 11B multiple quantum magic angle sample spinning (MQMAS), 11B–31P heteronuclear correlation (HETCOR) NMR and 11B 31P rotational echo double resonance (REDOR). For comparison, the crystalline borophosphates BPO4 and Na5B2P3O13 were included in the investigations. The latter compound shows three sharp 31P resonances at -0.2, -2 and -8 ppm and two BO4 sites that can only be resolved by MQMAS. The 17O NMR spectra were recorded using both the static echo method at medium magnetic field (9.4 T) as well as MAS and MQMAS methods at high field (17.6 T). In total, five oxygen sites were identified in these borophosphate glasses: P–O–P, NaO–P, P–O–B, B–O–B, NaO–B. However, these five sites are not present simultaneously in any of the glasses. The 17O MQMAS spectra prove that P–O–B links play a major role in borophosphate glasses. These results are confirmed by the complementary 11B MAS spectra that show the presence of asymmetric and symmetric trigonal groups BO3a and BO3s and two tetrahedral BO4 units. 11B 31P REDOR NMR is used to give independent information to assign the 11B lines to structural units present in the glasses. These REDOR measurements reveal that B–O–P bonds are present for each borate unit, including the BO3 groups. Particularly, a structural proposal for the two different BO4 resonances is given in terms of a different number of bonded phosphate tetrahedra. The 31P MAS spectra are usually broad and not well resolved. It is shown by 11B–31P HETCOR NMR that a possible structural assignment of a 31P signal at about -20 ppm to Q2 units as in binary sodium phosphate glasses is wrong and that the phosphate tetrahedron belonging to this resonance must be connected to borate groups KW - NMR KW - Sodium borophosphate glasses KW - Glass structure KW - NA5B2P3O13 KW - O-17 NMR KW - REDOR KW - MQMAS PY - 2005 DO - https://doi.org/10.1016/j.ssnmr.2004.06.009 SN - 0926-2040 SN - 1527-3326 VL - 27 IS - 1-2 SP - 50 EP - 64 PB - Academ. Press CY - Orlando, Fla. AN - OPUS4-11015 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zeyer, M. A1 - Montagne, L. A1 - Jäger, Christian T1 - Measuring oxygen-phosphorus distances and the orientation of electric field gradient tensors using 17O-{31P} REDOR in phosphate glasses N2 - Rotational echo double resonance (REDOR) of spin- nuclei is an extremely useful tool for the determination of distances in solids as well as of relative orientations of chemical shift and dipole tensors. We present the corresponding version for measuring the relative orientation of electric quadrupole and dipole tensors and demonstrate its applicability for non-bridging oxygens in phosphate glasses using 17O–{31P} REDOR NMR. The orientational information is found in the changes of the second-order quadrupole patterns as a function of the echo delay. Results and numeric simulations are presented for 17O–{31P} REDOR NMR of 17O-enriched sodium phosphate glasses. For non-bridging oxygens, the symmetric quadrupole tensor is found to be aligned along the phosphorus–oxygen bond. The distance between P and the non-bridging oxygen is calculated for two glasses of different compositions. KW - REDOR KW - Quadrupolar nuclei KW - O-17-{P-31} double resonance KW - Phosphate glasses PY - 2003 DO - https://doi.org/10.1016/S0926-2040(03)00012-2 SN - 0926-2040 SN - 1527-3326 VL - 23 IS - 3 SP - 136 EP - 144 PB - Academ. Press CY - Orlando, Fla. AN - OPUS4-11018 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zeyer, M. A1 - Montagne, L. A1 - Jäger, Christian A1 - Palavit, G. T1 - 17O NMR of Crystalline Sodium Trimetaphosphate PY - 2002 SN - 0918-4783 VL - 13 SP - 275 EP - 278 CY - Tokyo AN - OPUS4-11022 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -