Coordination of sodium ions in NaAlO 2 -SiO 2 melts: a high temperature 23 Na NMR study

Phosphate speciation in sodium borosilicate glasses studied by nuclear magnetic resonance

“…The spectra significantly differ in chemical shift due to the different environment of Na + cations. The 23 Na chemical shift (d) is correlated to the sodiumoxygen distance, as was established by Maekawa et al [40]: d Na-O = À0.0119d + 2.5912. A longer Na-O distance is expected when sodium acts as a charge compensating ion for BO 4 tetrahedra rather than when it is located on non-bridging oxygens (Si-OÁ Á ÁNa) [41].…”

In situ high temperature 27Al NMR study of structure and dynamics in a calcium aluminosilicate glass and melt

“…Many studies of the chemical structure of a wide range of CAS compositions have been performed using solid-state NMR, which is a very useful technique for obtaining shortand medium-range structure, including spectra for 29 Si [1,2], 27 Al [1][2][3][4][5][6], and 17 O [7][8][9][10]. In addition to such common nuclides for NMR measurements, 43 Ca NMR experiments have been performed on calcium/magnesium aluminosilicate glasses very recently [11,12].…”

“…In particular, because the spin-lattice relaxation time constant T 1 is very sensitive to different types of diffusive motion, NMR relaxation has been studied for nuclides such as 29 Si [13,15,18,19], 27 Al [21,24,25], 11 B [26], 23 Na [18,19,28,31,32], 7 Li [31], 25 Mg [32,34]. Of these, the relaxation mechanisms of silicon and alkali ions have been relatively well characterized.…”

“…One-(1D) and two-dimensional (2D) in situ high temperature NMR spectra have been obtained to investigate the structures of a variety of oxide glasses and melts from the line shapes, the peak positions and the line widths for several nuclides, e.g. 29 Si [13][14][15][16][17][18][19][20], 27 Al [20][21][22][23][24][25], 11 B [26,27], 23 Na [18][19][20][28][29][30][31][32], 7 Li [31,33], 25 Mg [32,34].…”

Effects of Thermal and Pressure Histories on the Chemical Strengthening of Sodium Aluminosilicate Glass

“…Such modification of the Na environment was assumed to result in a modification of the K + environment after K + -for-Na + ion exchange, which in turn affected ΔHV. 23 Na δCS has previously been reported to show a negative correlation with the Na-O bond length as a function of composition (Xue and Stebbins, 1993;Maekawa et al, 1997) and temperature (George and Stebbins, 1995;Maekawa et al, 1997) in silicate, aluminosilicate, borate, and germanate crystals. Furthermore, a decrease in 23 Na δCS has previously been found as a result of compression in glasses (Wu et al, 2009;Svenson et al, 2014a,b).…”