Structural study of lanthanum sodium aluminoborosilicate glasses by NMR spectroscopy

An investigation of Al2O3 induced variations in the structural parameters in strontium borosilicate glasses using solid state NMR

“…This assignment was further validated by comparing it with the 29 Si chemical shift of crystallised mineral samples and 29 Si NMR of aluminoborosilicate glasses. 23,26–29 For all the glasses, the peak at −110 ppm having an asymmetric line shape suggests the presence of Q 4 species with Si and non-Si neighbours. The Q 4 species in aluminosilicate glass has a chemical shift from −86 to −117 ppm.…”

“…16,17 In this study, a series of strontium alumina borosilicate glasses, prepared with a systematic substitution of B 2 O 3 by Al 2 O 3 were analyzed using multinuclear solid state NMR. The variations in the network speciation in the glass, after incorporating the Al are studied using 27 Al, 11 B, 29 Si MAS, and 27 Al, and 11 B MQMAS NMR. From the 27 Al, 11 B, and 29 Si SSNMR spectra, the occupancy of the different sites has been elucidated for all the compositions.…”

“…The variations in the network speciation in the glass, after incorporating the Al are studied using 27 Al, 11 B, 29 Si MAS, and 27 Al, and 11 B MQMAS NMR. From the 27 Al, 11 B, and 29 Si SSNMR spectra, the occupancy of the different sites has been elucidated for all the compositions. The average coordination number of network forming oxides (n o A ) and the oxygen packing fraction (Z o ) of the glasses have been evaluated for all the compositions.…”

Network Structure and Properties of Lithium Aluminosilicate Glass

“…The 27 Al MAS NMR peaks of the seven glass samples were all asymmetric composite peaks with a relatively broad distribution due to the quadrupole-broadening and localized-bonding environment related to compositional complexity, and the chemical shift in the resonance peak was ~42 ppm; the peak shapes were also roughly similar, indicating that the morphologies of the aluminum in the glass samples were relatively similar. With the increase in boron oxide content, the chemical shift in the peak shifted to high field, which may have been due to the fact that the oxygen in the Al-O bond carries low formal charge, and the amount of non-bridging oxygen in the Al-O network may be decreasing or the second element adjacent to it may change (B III or Si is preferably to B IV and Al IV ) [41]. In addition, the spectral peak widened asymmetrically toward the low-chemical-shift direction, which may have been related to the appearance of the high coordination of aluminum ions and the change in quadrupole-coupling parameters.…”

“…The presence of boron or aluminum resulted in a shift in the chemical shifts, and the substitution of [SiO 4 ] with Al IV or B IV increased the chemical shift values by approximately 5 ppm [44]. Similarly, the presence of non-bridging oxygen atoms within the silicon coordination polyhedron caused the peaks to shift toward the high fields due to the high formal charge carried by oxygen [41]. From the fitting calculation results of the 29 Si NMR spectra (Figure 3b), it can be seen that the main species in the glass network structure was Q4 (0Al) , followed by Q4 (1Al) ; the area percentage of the two exceeded 60%, and Q4 (3Al) and Q4 (4Al) contents were low.…”