Synthesis, structural and magnetic characterization of highly ordered single crystalline BiFeO3 nanotubes

• Published in: Materials research bulletin 2013-04, Vol.48 (4), p.1593-1597
• Main Authors: de Oliveira, L.A.S., Pirota, K.R.
• Format: Article
• Language: English
• Subjects: A. Nanostructures; B. Chemical synthesis; C. Electron microscopy; D. Magnetic properties
• ISSN: 0025-5408; 1873-4227
• DOI: 10.1016/j.materresbull.2012.12.066

[Display omitted] ► Highly ordered BiFeO3 nanotubes with 65nm of diameter and 3μm of length. ► Its morphology is smooth revealing, by TEM, a single crystalline structure. ► Suppression of the antiferromagnetic helical order giving rise to ferromagnetism. ► The large length-to-diameter ratio of the BiFeO3 nanotubes induced an uniaxial shape anisotropy which is added to the magnetocrystalline anisotropy. In this work, we report on the fabrication of highly ordered single crystalline BiFeO3 (BFO) nanotubes by a sol–gel technique using two-step anodic aluminum oxide (AAO) as template. We prepared BFO nanotubes with dimensions of 65nm in diameter and 3μm in length, as confirmed by scanning electron microscopy (SEM) measurements. The obtained single crystalline nanotubes present the expected pure phase (BiFeO3) as confirmed by energy-dispersive X-ray spectroscopy (EDX), selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). In addition to the antiferromagnetic behavior, the magnetization curves of the BFO nanotubes also present a ferromagnetic response, which holds from 2 to 300K. This desirable behavior is associated to the break of the antiferromagnetic helical spin ordering of the BFO nanotubes. Besides the magnetocrystalline anisotropy, the large length-to-diameter ratio induced an uniaxial shape anisotropy, attested by the applied magnetic field angle measurements.