Author | dc.contributor.author | Nascimento, Otaciro R. | |
Author | dc.contributor.author | Magon, Claudio José | es_CL |
Author | dc.contributor.author | Lopes, L. V. S. | es_CL |
Author | dc.contributor.author | Donoso, José Pedro | es_CL |
Author | dc.contributor.author | Benavente Espinosa, Eglantina | es_CL |
Author | dc.contributor.author | Páez, J. | es_CL |
Author | dc.contributor.author | Lavayen, Vladimir | es_CL |
Author | dc.contributor.author | Santa Ana, María Angélica | es_CL |
Author | dc.contributor.author | González Moraga, Guillermo | es_CL |
Admission date | dc.date.accessioned | 2009-06-02T12:12:41Z | |
Available date | dc.date.available | 2009-06-02T12:12:41Z | |
Publication date | dc.date.issued | 2006 | |
Cita de ítem | dc.identifier.citation | MOLECULAR CRYSTALS AND LIQUID CRYSTALS Volume: 447 Pages: 551-560 Published: 2006 | en |
Identifier | dc.identifier.issn | 1542-1406 | |
Identifier | dc.identifier.uri | https://repositorio.uchile.cl/handle/2250/118846 | |
Abstract | dc.description.abstract | This work describes an Electron Paramagnetic Resonance (EPR) and Nuclear Magnetic Resonance (NMR) study of the vanadium pentoxide xerogel V2O5:nH(2)O with n approximate to 1.8 Experiments were performed in the temperature range 65 K - 310 K. The EPR spectrum at high temperatures exhibits the typical liquid-like eight lines-hyperfine structure. At low temperatures the EPR spectrum change to a V4+ anisotropic powder spectra. These two different regimes can be delimited by a transition temperature region centered at 280 K. Numerical simulations of the EPR spectra in the two temperature limits are in good agreement with the experimental data. Proton (H-1) NMR lineshapes, as functions of temperature were measured in the range 150-323 K and indicate that nuclear motional narrowing is effective at temperatures above 210 K, with an activation energy of 0.14 eV. The NMR spin-lattice relaxation recovery, associated to protons in the water molecules, was found to be non-exponential throughout the temperature range and described by two different relaxation processes. The slow relaxing component is temperature-independent and was attributed to water molecules located far from V4+ ions. The temperature dependence of the fast relaxing component shows maximum at around 260 K, suggesting a relaxation process sensitive to the temperature induced dynamic structural changes in the vanadium oxide matrix. | en |
Lenguage | dc.language.iso | en | en |
Publisher | dc.publisher | TAYLOR & FRANCIS LTD | en |
Keywords | dc.subject | EPR | en |
Título | dc.title | Magnetic resonance study of vanadium pentoxide gels | en |
Document type | dc.type | Artículo de revista | |