Formation of ordered cobalt nanowire arrays in the mesoporous silica channels

• Published in: Pure and applied chemistry Vol. 78; no. 9; pp. 1749 - 1757
• Main Authors: Chernysheva, Marina V., Sapoletova, Nina A., Eliseev, Andrei A., Lukashin, Alexey V., Tretyakov, Yuri D., Goernert, Peter
• Format: Journal Article
• Language: English
• Published: Berlin De Gruyter 01.09.2006; Walter de Gruyter GmbH
• Subjects: Anisotropy; Chemical analysis; Cobalt; Coercivity; Crystallization; Data storage; Electronic devices; Form factors; Hydrophobicity; magnetic data storage; Magnetic measurement; magnetic nanowires; Magnetic permeability; Magnetic saturation; Magnetic storage; mesoporous silica; Metal compounds; Nanocomposites; Nanowires; ordered nanowire arrays; Organic chemistry; Recording; Recording instruments; Silica; Silicon dioxide; Synthesis; Temperature dependence; Transmission electron microscopy; X-ray diffraction
• ISSN: 0033-4545; 1365-3075
• DOI: 10.1351/pac200678091749

Here we report the synthesis and investigation of cobalt nanowire arrays using mesoporous silica as a host material. In the present work, a novel variant of synthesis of ordered magnetic nanowires in the mesoporous silica matrix was suggested. The method is based on incorporation of a hydrophobic metal compound Co (CO) into the hydrophobic part of the silica-surfactant composite. The amount of cobalt intercalated into the mesoporous matrix was measured by chemical analysis (~5 wt %). Additional thermal modification was performed in order to provide a crystallization process of the cobalt nanowires. The prepared nanocomposites were characterized by X-ray diffraction (XRD), small-angle X-ray spectroscopy (SAXS), transmission electron microscopy (TEM), nitrogen capillary adsorption method (BET and BJH), and magnetic measurements. The anisotropy parameters of nanowires were determined using temperature dependence of magnetic susceptibility. For cobalt-containing sample annealed at 300 °C (form factor of nanowire higher than 16), the coercive force at room temperature was found to be 42.2 kA/m at saturation magnetization of 0.5 A.m /kg, which is nearly sufficient for modern information recording media. According to TEM studies, cobalt particles are uniform and well ordered in the silica matrix. Thus, the suggested method leads to one-dimensional anisotropic nanostructures, which could find an application in high-density data storage devices.