Eur. Phys. J. B 37, 329-337 (2004)
https://doi.org/10.1140/epjb/e2004-00063-7

Magnetic properties of Fe and Ni nanoparticles formed in triethoxysilane films by ion irradiation or thermal processing

¹ CSNSM-IN2P3, bâtiment 108, 91405 Orsay Campus, France
² SPEC-DRECAM, CEA Saclay, 91191 Gif-sur-Yvette, France
³ LSI-DRECAM, CEA Saclay, 91191 Gif-sur-Yvette, France
⁴ Centre de Recherche et de Restauration des Musées de France, 6 rue des Pyramides, 75041 Paris Cedex 01, France

Corresponding author: ^a pivin@csnsm.in2p3.fr

Received: 22 September 2003
Revised: 4 December 2003
Published online: 2 April 2004

Abstract

Ion irradiation or heat treatments in vacuum of gel films prepared from mixtures of triethoxysilane with Fe and Ni nitrates permits to obtain a precipitation of metal particles in a glassy matrix, because these gels contain hydrido groups able to reduce Fe³⁺ and Ni²⁺ ions. The precipitation under irradiation is ascribed to the electronic excitations produced by the ions and the volume of metallic phase increases in proportion to the amount of energy transferred to electrons. The metal particles exhibit a narrower range of sizes than in films submitted to heat treatments in vacuum. Experiments of electron spin resonance indicate that the magnetic behavior of irradiated films is affected by a stress-induced anisotropy field. Films containing 3 to 7 at% Fe are in a superparamagnetic state in a given range of temperatures while the magnetic moments of nickel particles in films with similar metal contents exhibit a stronger correlation, due to a larger yield of precipitation and to the stress.