Aging effect on vanadium oxide hybrid nanotubes

• Published in: Journal of physics. Condensed matter Vol. 31; no. 50; p. 505701
• Main Authors: Saleta, Martín E, Tobia, Dina, Figueroa, Santiago J A, López, Carlos A, Granada, Mara, Sánchez, Rodolfo D, Malta, Marcos, Torresi, Roberto M
• Format: Journal Article
• Language: English
• Published: England IOP Publishing 18.12.2019
• Subjects: aging effects; magnetic quantification; vanadium oxide nanotubes; XANES quantification
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/1361-648X/ab3ed3

Vanadium oxides present a rich magnetic phase diagram depending on the oxidation state of the V ions. In particular the vanadium oxide nanotubes (VOx NTs) present several promising perspectives for different technological applications for which it is essential to know the oxidation state of V ions, as well as to evaluate the stability with the aging time of the tubes. In this work we present a systematic study of the time evolution of the magnetic properties of VOx NTs. For this complete characterization, we used electron spin resonance (ESR) and dc-susceptibility techniques, which were supplemented with TEM microscopy and XANES. We observed that for aging in normal environmental conditions of pressure, temperature and humidity, the V4+ ions oxidize to V5+ . Although the multiwall tubular structure is maintained, this oxidation process produces a marked change in the magnetic properties. We conclude that the aging of the samples affects the V4+ /V5+ relationship in the VOx NTs, which may contribute to explain the significant dispersion of data reported in the bibliography.