| Autor: |
Durand-Le Floch, M., Pannetier, J., Doremieux-Morin, C., Arribart, H. |
| Předmět: |
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| Zdroj: |
Journal of Chemical Physics; 5/1/1986, Vol. 84 Issue 9, p4760, 9p |
| Abstrakt: |
The defect pyrochlores H2Ta2O6, HTaWO6, and their hydrates have been studied by proton nuclear magnetic resonance. Rigid lattice spectra of H2Ta2O6 and HTaWO6 exhibit a large Lorentzian contribution which indicates a statistical distribution of the protons over the 48 f sites of the structure and implies the pairing of protons bonded to the same oxygen [r(H–H)=1.5 Å]. Long range diffusive motion is deduced from the relaxation rates; in all four compounds the diffusion mechanism can be explained by using two independent correlation times τ1 and τ2. The activation energy corresponding to the jump of a proton to the nearest neighbor vacant position is the same (E1=0.15 eV) for three of the pyrochlores. The low temperature spin lattice relaxation of the anhydrous compounds H2Ta2O6 and HTaWO6 is governed by the existence of unequal potential wells. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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