Sharif Digital Repository

FePt nanoparticles were synthesis via high-temperature solution phase. Monodispersed 3.5 nm FePt nanoparticles were first obtained by reduction of FeCl2.4H2O and Pt(acac)2. These preformed FePt nanoparticles were then combined with NaCl to prevent from sintering after annealing. The 1 micron salt particles were fabricated by ultra-sonic vibration method and used as the separating media. Annealing studies show that these salt-matrix FePt nanoparticles are stable after annealing at 700 °C for 4 h. The annealed FePt particles diameter increases from 4 to 25 nm as observed by TEM. The magnetic properties are largely affected by annealing temperature. The role of these salt particles on sintering... 

The variation of the applied field results in a subsequent change of magnetization with time. There is a relationship between the coercivity (Hc), as the equilibrium characteristic of the system, and its magnetic stability (1/S), as a parameter characterizing the time dependence. 1/S as a function of Hc has been measured and studied for different Fe1-xCox samples. We synthesized several samples with different values of x by applying various magnetic fields during the grains' growth, and observed a linear relationship between 1/S and Hc. © 2007 Elsevier B.V. All rights reserved  

The single-domain particles, especially FeCo fine particles have many applications in magnetic information technology. We have prepared Fe 1-xCox fine particles for different x by borohydride method and measured the magnetic and structural properties of the samples. We have then determined the variations of coercivity and anisotropy energy versus x in Fe1-xCox fine particles. The obtained results have been analyzed on the basis of various magnetic anisotropies. Magnetic anisotropies affect the coercivity of the medium for each x as follows: shape and crystal anisotropies for x=0, surface and crystal anisotropies for x=1, shape, induced and crystal anisotropies for x=0.3 and 0.5, and shape...