| Autor: |
Schneider, José, Oliveira, Samuel L., Nunes, Luiz Antonio O., Panepucci, Horácio |
| Předmět: |
|
| Zdroj: |
Journal of the American Ceramic Society; Feb2003, Vol. 86 Issue 2, p317, 8p |
| Abstrakt: |
High-resolution solid-state [sup 31]P, [sup 27]Al, and [sup 23]Na nuclear magnetic resonance (NMR), Raman spectroscopy, differential scanning calorimetry, and density measurements were used to characterize the local structure of the glasses (1-x)(NaPO[sub 3])[sub 3]· xAl(PO[sub 3])[sub 3]. A systematic increase in density, glass transition temperature (T[sub g]), and frequencies of P-O stretching vibrations for terminal nonbridging oxygens (NBOs) was observed as the Al content was increased. A change of slope in the behavior of T[sub g] as a function of x was clearly detected around x = 0.25 ± 0.03. Also, changes of behavior in the [sup 23]Na NMR line shape and in the Raman band of the PO[sub 2] symmetric vibration are detected for concentrations higher than x = 0.17. According to these facts, a reorganization of the network affecting the degree of connectivity between phosphate chains is proposed to explain the observed behaviors of T[sub g] and P-NBO vibrations in these glasses. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
|
