TY - JOUR
T1 - Solid-state NMR investigations of sodium-cesium mixed-alkali phosphate glasses
AU - Prabakar, S.
AU - Mueller, K. T.
N1 - Funding Information:
KTM is an Alfred P. Sloan Research Fellow. This report is based upon work originally carried out with support from the National Science Foundation under Grant no. DMR-9458053 and with support from the Research Corporation (Cottrell Scholar Award to K.T.M.).
PY - 2004/12/1
Y1 - 2004/12/1
N2 - Simultaneous structural correlations between 31P and 23Na nuclei and between 31P and 133Cs nuclei in a series of mixed-alkali sodium-cesium phosphate glasses are investigated by transfer of populations via double resonance (TRAPDOR) NMR spectroscopy. The variations in spatial proximity between 31P nuclei at the center of phosphate tetrahedra and sodium (or cesium) modifier ions in the system xCs 2O: (56 - x) Na2O: 44 P2O5 (where x = 0 - 40) are followed systematically as a function of alkali oxide composition. The TRAPDOR method probes specific interactions between 31P and 23Na (or 133Cs) nuclei through the direct nuclear spin dipolar interaction. 31P MAS NMR spectra of these polyphosphate glasses reveal two phosphate environments corresponding to phosphorus atoms with two (Q2) and one (Q1) non-bridging oxygens in a 2.7:1 ratio, as expected from a simple depolymerization model. The Q 2/Q1 ratios measured using the TRAPDOR technique show a mixed-alkali effect as a function of alkali oxide concentration, revealing a maximum in the effect for 31P-23Na pairings and a minimum interaction for 31P-133Cs at concentrations of approximately 35mol% for each of the respective alkali cations.
AB - Simultaneous structural correlations between 31P and 23Na nuclei and between 31P and 133Cs nuclei in a series of mixed-alkali sodium-cesium phosphate glasses are investigated by transfer of populations via double resonance (TRAPDOR) NMR spectroscopy. The variations in spatial proximity between 31P nuclei at the center of phosphate tetrahedra and sodium (or cesium) modifier ions in the system xCs 2O: (56 - x) Na2O: 44 P2O5 (where x = 0 - 40) are followed systematically as a function of alkali oxide composition. The TRAPDOR method probes specific interactions between 31P and 23Na (or 133Cs) nuclei through the direct nuclear spin dipolar interaction. 31P MAS NMR spectra of these polyphosphate glasses reveal two phosphate environments corresponding to phosphorus atoms with two (Q2) and one (Q1) non-bridging oxygens in a 2.7:1 ratio, as expected from a simple depolymerization model. The Q 2/Q1 ratios measured using the TRAPDOR technique show a mixed-alkali effect as a function of alkali oxide concentration, revealing a maximum in the effect for 31P-23Na pairings and a minimum interaction for 31P-133Cs at concentrations of approximately 35mol% for each of the respective alkali cations.
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U2 - 10.1016/j.jnoncrysol.2004.08.253
DO - 10.1016/j.jnoncrysol.2004.08.253
M3 - Conference article
AN - SCOPUS:9744280478
SN - 0022-3093
VL - 349
SP - 80
EP - 87
JO - Journal of Non-Crystalline Solids
JF - Journal of Non-Crystalline Solids
IS - 1-3
T2 - Glass Science for High Technology. 16th University Conference
Y2 - 13 August 2004 through 15 August 2004
ER -