11B and 27Al NMR studies of glasses in the system Na2OB2O3Al2O3 (“NABAL”)

Experimental determination of the effect of the ratio of B/Al on glass dissolution along the nepheline (NaAlSiO4)–malinkoite (NaBSiO4) join

“…The results shown in Fig. 6 resemble those from spectra observed by others for related boron-containing glasses (Gresch et al, 1976;Geisinger et al, 1988;Bunker et al, 1991;Darab et al, 1997Darab et al, , 1999Pierce et al, 2008a). For example Bunker et al (1991) showed that by increasing the mol% Al 2 O 3 , the fraction of [4] B decreases in alkalineearth boroaluminate glasses in the Al 2 O 3 -B 2 O 3 -MO ternary system [where M refers to divalent cations such as Ba, Ca, and Mg (Bunker et al, 1991)].…”

“…Aluminum-27. MAS-NMR In general, Al 2 O 3 is considered to be a network former in glasses (Gresch et al, 1976;El-Damrawi et al, 1993;Du and Stebbins, 2005a). For example, addition of Al to Na 2 O-SiO 2 glasses decreases the concentration of nonbridging oxygen sites through the formation of tetrahedrally coordinated Al-atoms that are charge-compensated by Na and form [AlO 4 ]-Na units (Maekawa et al, 1990(Maekawa et al, , 1991.…”

“…The use of spectroscopic techniques, such as magic-angle spinning nuclear magnetic resonance (MAS-NMR) and Raman, have allowed researchers to obtain insights into the structure of amorphous materials like glass (Jellison and Bray, 1978;Mysen et al, 1982Mysen et al, , 2003Murdoch et al, 1985;Neuville and Mysen, 1996;Sen et al, 1998;Stebbins, 1998, 1999;Stebbins, 1999, 2002;Stebbins et al, 2000;Lee et al, 2001;Du and Stebbins, 2005a,b). For example, 27 Al and 29 Si MAS-NMR studies have shown that the addition of Al 2 O 3 , a network former, to alkali silicate glasses causes non-bridging oxygen sites (NBO sites) to be converted to bridging-oxygen (BO) sites as the additional oxygen required for Al to occupy a tetrahedral coordination is removed from the NBO site (Gresch et al, 1976;Bunker et al, 1990;Maekawa et al, 1991;El-Damrawi et al, 1993). For these glasses, aluminum is charge-compensated by an alkali element, such as Na, to form tetrahedral [AlO 4 ]-Na linkages, which are similar to the SiO 4 tetrahedra.…”

Network connectivity in aluminoborosilicate glasses: A high-resolution 11B, 27Al and 17O NMR study

“…It has generally been found that Al 3+ behaves as a network forming cation in alkali or alkaline-earth aluminoborate glasses [14][15][16][17][18][31][32][33]. In postulated reaction schemes, the addition of alkali or alkaline-earth oxides to B 2 O 3 and Al 2 O 3 results in the formation of [4] B and [4] Al [31,33].…”

“…Boron-11 wide-line NMR has long been one of the major tools to study the short-range structure of boratecontaining glasses, such as alkali borate, borosilicate, and aluminoborate glasses [6][7][8][9][10][11][12][13][14][15][16][17][18]. In many systems, this technique has successfully determined the fraction of tetrahedral (BO 4 groups, [4] B) and trigonal boron species (BO 3 groups, [3] B) including symmetric and asymmetric trigonal boron groups ( [3] B connected to three vs. to two or one bridging oxygens).…”