Nanocomposites and nanomaterials

Influence of iron content on magnetic properties of EB-PVD-condensates of Fe-NaCl with magnetite nanoparticles
Lytvyn S.Ye., Kurapov Yu.A., Didikin G.G.
E. O. Paton Electric Welding Institute of the NAS of Ukraine, 
Kazymyr Malevych, 11, Kyiv- 03150, Ukraine
E-mail: lytvynse@hotmail.com
	
Fig. 1. Influence of Fe content on MsFe saturation magnetization and Hc coercive force in EB-PVD condensates of Fe-NaCl.	
Iron nanoparticles in condensates of the system 10…43 wt. % Fe-NaCl obtained by electron beam evaporation and co-condensation in vacuum of molecular beams of Fe and NaCl (EB-PVD method) were studied. After depressurization of the vacuum chamber, small nanoparticles of iron in the porous structure of NaCl are oxidized in air to Fe3O4, and larger ones do not have time to fully oxidize and have a nucleus of pure iron inside. The structure and size of nanoparticles in Fe-NaCl condensates, their phase and chemical composition, and magnetic properties were studied using transmission electron microscopy (TEM), X-ray diffraction (XRD), dynamic light scattering (DLS), and vibration magnetometers. The size of Fe3O4 nanoparticles in condensates depending on the temperature of their synthesis and the size of nanoparticle crystallites depending on the concentration of iron in condensates were determined. The influence of the amount of iron in the condensates on the crystallite size of nanoparticles is shown. According to XRD analysis, the size of Fe3O4 crystallites in the concentration range 2…15 at. % Fe is in the range of 3…14 nm, and in the range of 20…30 at. % Fe - 17…22 nm. The average size of Fe3O4 crystallites (8…15 nm) obtained at a substrate temperature of 45 °C increases as the substrate temperature increases to 25…40 nm (410 °C). It should be noted that in nanoparticles the phase of pure iron is detected when the iron content in the condensate is more than 20 at. % Fe. It is proved that the condensation temperature can be considered as a reliable factor for regulating the size of nanoparticles in the technological process. A study of the distribution of the hydrodynamic size of aggregates of Fe3O4 nanoparticles in aqueous colloids with dextran was performed. An increase in the saturation magnetization and coercive force of Fe-NaCl condensates with magnetite nanoparticles with increasing iron content was revealed.