Polyhedral Arrangements in Lanthanum Aluminoborate Glasses
We have used magic-angle spinning nuclear magnetic resonance (MAS NMR) and Raman spectroscopy to examine the polyhedral arrangements in ternary lanthanum aluminoborate glasses. We have characterized two glass-forming series: xAl 2O 3·(1-x)LaB 3O 6 and 0.25La 2O 3·yAl 2O 3·(1-y)-B 2O 3. 11B MAS NMR reveals a decrease in the fraction of four-coordinated boron atoms with increases in the Al 2O 3 content in both series. 27Al MAS NMR has detected four-, five- and six-coordinated aluminum atoms in complex aluminoborate networks similar to those reported elsewhere for alkaline-earth aluminoborate glasses. Raman spectroscopy reveals a variety of borate and aluminoborate moieties, including isolated groups as well as methaborate chains and rings. These results indicate that the La 3+ ion acts as a modifier to the aluminoborate network.
R. K. Brow et al., "Polyhedral Arrangements in Lanthanum Aluminoborate Glasses," Journal of the American Ceramic Society, American Chemical Society (ACS), Jan 1997.
The definitive version is available at http://dx.doi.org/10.1111/j.1151-2916.1997.tb02970.x
Materials Science and Engineering
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© 1997 American Chemical Society (ACS), All rights reserved.