Silica coated nanoparticles: Synthesis, magnetic properties and spin structure

JOURNAL OF ALLOYS AND COMPOUNDS

卷:483

Article; Proceedings Paper

Mazaleyrat, F.¹  Ammar, M.¹  LoBue, M.¹  Bonnet, J. -P.²  Audebert, P.²  Wang, G. -Y.³  Champion, Y.³  Hytch, M.⁴  Snoeck, E.⁴ 

[1] ENS, SATIE, CNRS, UniverSud, F-94230 Cachan, France

[2] ENS, PPSM, CNRS, UniverSud, F-94230 Cachan, France

[3] Univ Paris 12, CNRS, ICMPE, F-94320 Thiais, France

[4] CNRS, CEMES, F-31055 Toulouse, France

关键词: Core-shell particles;    Nanomagnetism;    Ultrasonic synthesis;   

DOI  :  10.1016/j.jallcom.2008.08.121

来源: Elsevier

【 摘 要 】

In therecent years, magnetic nanoparticles have been extensively studied for their superparamagnetic properties providing useful labels in biology or for fundamental aspects including the size dependence of magnetic atomic moment and the effect of surface anisotropy. In most cases, the particles were smaller than 10 nm and interestingly, the sizes ranging between 10 and 100 nm have been poorly investigated until now. This is mainly due to the fact that usual chemical routes produce 5-10 nm oxide or metallic particles or eventually 20 nm at most. on the over side, atomization techniques yield particles in the micrometer range. Metallic particles are particularly interesting for better magnetic properties compared to oxides, but they have two big drawbacks: they are not biocompatible and they are conducting electricity. Consequently, it's necessary to produce core-shell particles, for which the shell is biocompatible and insulating and with a perfect control of thickness and uniformity of that shell. In this work, we are studying metallic particles synthesized by an original evaporation-condensation technique that produces particles of several tens of nanometers. We prepared hard magnetic cobalt particles and soft FeNi ones coated with a silica shell using a modified sol-gel method. Morphological and magnetic properties are presented, showing the efficiency of ultrasonic sol-gel process for that purpose. (C) 2008 Elsevier B.V. All rights reserved.

【 授权许可】

Free