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Ni,Zn/SiO2 FERRITE NANOCOMPOSITES PREPARED BY AN IMPROVED SOL-GEL METHOD AND THEIR CHARACTERISATION

M. Stefanescu1,* , C. Caizer2, M. Stoia1, O. Stefanescu1

Affiliation

  1. „Politehnica” University of Timisoara, Faculty of Chemistry and Chemical Engineering, P. Victoriei no. 2, 1900-Timisoara, Romania
  2. West University of Timisoara, Faculty of Physics, Department of Electricity and Magnetism, Bd. Parvan no. 4, 1900-Timisoara, Romania

Abstract

Ni,Zn/SiO2 nanocomposites with magnetic properties were obtained by an improved sol-gel method (hibrid gels) by using Si(OC2H5)4 Zn, Ni, Fe, nitrates, ethanol (C2H5OH) and ethylene glycol. After drying and calcinations of the gels at temperatures between 600-1300 oC, the reaction products were characterized by thermal analysis, IR-Spectroscopy, X-Ray diffraction and magnetic measurements. Unlike the case when we used only the thermal decomposition of the complex combination with glyoxilate dianion ligand method, in order to obtain nanocrystalline Ni-Zn ferrite, in this case we used a combined method, between the first one and the known sol-gel method. The special result of this proposed method is the producing of ultra fine magnetic nanoparticles, with diameters even smaller than 3.5 nm. The presence of the ferimagnetic phase was clearly evidenced from magnetic measurements starting even from low temperatures (550 oC) for a weight percentage ferrite: SiO2 of 35:65. The magnetic behaviour of ZnxNi(1-x)Fe2O4 (x = 0.35) ferrite nanoparticles, in silica matrix, obtained after thermal treatment at 600 oC in a quasistatic magnetic field (50 Hz), is super paramagnetic for a 3.5 nm mean diameter, respectively ferromagnetic for 6 nm mean diameter..

Keywords

Ni-Zn ferrite, Sol-gel, Glyoxilate, DTA, XRD, FT-IR, Magnetic properties.

Submitted at: Aug. 18, 2004
Accepted at: March 23, 2005

Citation

M. Stefanescu, C. Caizer, M. Stoia, O. Stefanescu, Ni,Zn/SiO2 FERRITE NANOCOMPOSITES PREPARED BY AN IMPROVED SOL-GEL METHOD AND THEIR CHARACTERISATION, Journal of Optoelectronics and Advanced Materials Vol. 7, Iss. 2, pp. 607-614 (2005)