Abstract
Spinel cobalt ferrite nanowires were successfully prepared in mesoporous silica SBA-15 as a host matrix followed by slow thermal decomposition of the precursors inside the silica-based template. The formation and phase control of as-synthesized nanostructured cobalt ferrites were confirmed by X-ray diffraction (XRD) measurements at different annealing temperatures ranging from 500 to 1000 degrees C. The one-dimensional spinel nanostructures were identified by recording the transmission electron microscopy (TEM) images after a selective removal of the silica template in aqueous solution of NaOH. The final product was also characterized using infrared spectroscopy (FT-IR) and vibration sample magnetometer (VSM). The presence of SBA-15 lowers the formation temperature of cobalt ferrite nanowires compared to the corresponding bulk material. The nanowires annealed up to 700 degrees C exhibited magnetic behavior characteristic for soft magnetic materials, whereas samples annealed at temperature higher than 700 degrees C revealed magnetic behavior characteristic for hard magnetic materials with rectangular form and large coercive field. (C) 2010 Elsevier B.V. All rights reserved.