INVESTIGADORES
SANCHEZ Rodolfo Daniel
artículos
Título:
Thermal stability and the magnetic properties of hybrid vanadium oxide-tetradecylamine nanotubes
Autor/es:
M.E. SALETA; C. A. LÓPEZ; M. GRANADA; H. E. TROIANI; R. D. SANCHEZ; M. MALTA; R. M. TORRESI
Revista:
JOURNAL OF APPLIED PHYSICS
Editorial:
AMER INST PHYSICS
Referencias:
Lugar: New York; Año: 2012 vol. 112 p. 53912 - 53912
ISSN:
0021-8979
Resumen:
Vanadium oxide nanotubes (NTs) were synthesized by the sol-gel method
followed by a long-term hydrothermal treatment. The obtained nanotubes
have a multiwall structure, and 70% of vanadium ions are in the V 4+
state. This percentage was derived by evaluating three components of
the magnetic susceptibility; namely, (i) the paramagnetic Curie-Weiss
behavior, (ii) antiferromagnetic dimers, and (iii) magnetic trimers. The
as-made NTs were annealed in situ in the cavity of the electron
paramagnetic resonance (EPR) spectrometer. The line shape changes
irreversibly at 390 K, and the EPR susceptibility presents an anomaly at
425 K. These changes are interpreted as a partial oxidation of the V 4+ ions and consequently a decrease in the concentration of the magnetic species. The quantification of the V 4+ ions of the annealed NTs reveals a diminution to 39% of V 4+,
a weakening of the Curie-Weiss and antiferromagnetic dimers
contributions, and the suppression of magnetic trimers. Vibrational
studies confirm the decrease of V 4+ amount. © 2012 American Institute of Physics.