| Autor: |
Qi, F., Rier, C., Böhmer, R., Franke, W., Heitjans, Paul |
| Jazyk: |
angličtina |
| Rok vydání: |
2005 |
| Předmět: |
|
| Zdroj: |
Physical Review B 72 (2005), Nr. 10 |
| Popis: |
Nuclear magnetic resonance spectroscopy was used to study polycrystalline β-spodumene (β−LiAlSi2O6) as well as glassy specimens with the same chemical composition. 7Li spin-lattice relaxation measurements were carried out in a broad temperature range and for several Larmor frequencies. In addition to a pronounced rate maximum at high temperatures, stemming from the long-range Li motion in these aluminosilicates, we found a weak maximum in the crystalline modification near 120K. The latter result confirms the existence of a local double-well structure in which the Li ions reside. The ionic motion was also monitored by solid- and stimulated-echo spectra as well as by the decay of the Jeener-Broekaert echo. Under conditions which are discussed in detail, the latter is a direct measure of the hopping correlation function. For the glass this function was found to decay faster and more stretched than that of the crystal at a given temperature. Furthermore, the relevant barriers against the high-temperature long-range Li motion are larger in the crystal as compared to the glass. © 2005 The American Physical Society. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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