Title :
Phase Transformation in Silica-Coated FePt Nanoparticles
Author :
Colak, Levent ; Hadjipanayis, George C.
Author_Institution :
Dept. of Phys. & Astron., Univ. of Delaware, Newark, DE, USA
Abstract :
Chemically synthesized FePt nanoparticles (NPs), with an average size of 5.8 nm, were coated with silica (SiO2) shells. The thickness of the silica shell could be controlled between 7.5-25 nm. A modified heating profile has been adopted with which silica shell cracking at high temperatures (1000degC) could be prevented. Even with prolonged heating for 24 h at 800degC, no sintering of the particles is observed. Low temperature (7 K) and room temperature magnetization scans show low coercivity values which are possibly due to a compositional distribution among the individual NPs.
Keywords :
coercive force; cracks; high-temperature effects; iron alloys; nanofabrication; nanoparticles; particle size; platinum alloys; shells (structures); silicon compounds; solid-state phase transformations; SiO2-FePt; coercivity; high temperature effects; magnetization; particle size; phase transformation; silica shell cracking; silica shell thickness; silica-coated nanoparticles; temperature 1000 C; temperature 7 K; temperature 800 C; time 24 h; FePt nanoparticles; silica coating; sintering prevention;
Journal_Title :
Magnetics, IEEE Transactions on
DOI :
10.1109/TMAG.2009.2026628
