Poster Presentation

¹Mohsen Mohammad Alizadeh ; ²Mohammad Almaci Kashi; ²Mohammad NoorMohammadi

¹Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan, Iran

²Department of Physics, University of Kashan, Kashan, Iran

Magnetic nanowires have many usages in magnetic hard disks for information storage, permanent magnets and in everyday products, including motors, generators, etc., which have been considered in recent years. The coercivity value of magnetic nanowires could be optimized by controlling their diameter and length precisely. There are different methods to fabricate nanowires, among which the electrochemical deposition is the most common one. However, it is not able to satisfy the demands of permanent magnets. Recently, liquid phase synthesis has been suggested due to its ease and high rate of crystallization. Here, cobalt magnetic nanowires are synthesized in different forms and dimensions during cobalt carboxylate salt recovery Co(II) in 1,2-Butanediol process by using a Solvothermal method. The resulting cobalt nanowires have a hexagonal crystal structure oriented along the (002) plane as the main axis of nanowires. Based on the transmission electron microscope (TEM) analysis, the length of the synthesized nanowires ranges from 200 to 300 nm, and their diameters are between 20 and 25 nm. Also, in accordance with X-ray diffraction analysis, by aligning of cobalt nanowires under an applied magnetic field, the (002) peak only remains, and the rest of peaks are eliminated. Due to the shape anisotropy and magnetocrystalline anisotropy as well as the cobalt nanowires’ orientation, a high value of coercivity is recorded at room temperature. By aligning of cobalt nanowires, the coercivity value increases almost two times. In other words, the coercivity of cobalt nanowires with random orientation is 4200 Oe, and that of nanowires aligned under the applied magnetic field is 7800 Oe. This is related to aligning of the magnetic moments in the same direction, leading to the coercivity enhancement. Based on the discrepancy between coercivity values of nanowires aligned in 0- and 90-degree angles, the alignment degree could be realized as well. Angular measurement of hysteresis loop shows that in nanowires aligned under the magnetic fields, the coercivity decreases by increasing the angle from 0 to 90 degrees. According to the results, residual magnetism goes through a downward trend by increasing the angle as well. Also, the amount of squareness as a parameter for measuring hardness or softness of magnetic materials decreased by increasing the angle from 0 to 90 degrees.

aligned; Co Nanowires; coercivity; hysteresis loop; Solvothermal