Polyhedral Arrangements in Lanthanum Aluminoborate Glasses

Autor:	David R. Tallant, Gary L. Turner, Richard K. Brow
Rok vydání:	2005
Předmět:	Magic angle Inorganic chemistry Center (category theory) chemistry.chemical_element NMR spectra database symbols.namesake Crystallography chemistry Content (measure theory) Materials Chemistry Ceramics and Composites symbols Lanthanum Ternary operation Raman spectroscopy Boron
Zdroj:	Journal of the American Ceramic Society. 80:1239-1244
ISSN:	1551-2916 0002-7820
DOI:	10.1111/j.1151-2916.1997.tb02970.x
Popis:	The authors have used magic-angle spinning nuclear magnetic resonance (MAS NMR) and Raman spectroscopy to examine the polyhedral arrangements in ternary lanthanum aluminoborate glasses. They have characterized two glass-forming series: xAl{sub 2}O{sub 3}{center_dot}(1{minus}x)LaB{sub 3}O{sub 6} and 0.25 La{sub 2}O{sub 3}{center_dot}yAl{sub 2}O{sub 3}{center_dot}(1{minus}y)-B{sub 2}O{sub 3}. {sup 11}B MAS NMR reveals a decrease in the fraction of four-coordinated boron atoms with increases in the Al{sub 2}O{sub 3} content in both series. {sup 27}Al 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{sup 3+} ion acts as a modifier to the aluminoborate network.
Databáze:	OpenAIRE
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