Coordination of B in K{sub 2}OSiO{sub 2}-B{sub 2}O{sub 3}-P{sub 2}O{sub 5} glasses using B K-edge XANES
- Univ. of Western Ontario, London (Canada); and others
High-resolution B K-edge X-ray absorption near-edge structure (XANES) spectra of K{sub 2}O-SiO{sub 2}-B{sub 2}O{sub 3}-P{sub 2}O{sub 5} glasses are reported using synchrotron radiation. Two prominent features, peak a at about 194.0 eV and peak b at about 198.0 eV, are observed. In the basis of the qualitative MO diagrams of BO{sub 3}{sup 3{minus}} and BO{sub 4}{sup 5{minus}} clusters, peak a is assigned to the transition of B 1s electrons to the unoccupied B 2p{sub z} ({pi}*) states for threefold-coordinated B ({sup [3]}B), and peak b is assigned to the transition of B 1s electrons to the unoccupied B {sigma}* states for fourfold-coordinated B({sup [4]}B). B K-edge XANES spectroscopy is established as a method for {open_quotes}fingerprinting{close_quotes} {sup [3]}B and {sup [4]}B in borate and borosilicate minerals, glasses, and melts. Also, the relative proportions of {sup [4]}B and {sup [3]}B in the borosilicate glasses are determined from the integrated peak areas for {sup [3]}B and {sup [4]}B edge peaks and are shown to be generally in good agreement with recent {sup 11}B MAS NMR measurements. However, the surface and near-surface structure of powder particles of perboric glasses containing P{sub 2}O{sub 5} appears to have a lower proportion of {sup [3]}B entities than the bulk. 27 refs., 4 figs., 1 tab.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 443382
- Journal Information:
- American Mineralogist, Vol. 80, Issue 9-10; Other Information: PBD: Sep-Oct 1995
- Country of Publication:
- United States
- Language:
- English
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