title: Microwave resonant and zero-field absorption study of doped magnetite prepared by a co-precipitation method.
abstract: Fe3O4 and ZnxFe3-xO4 pure and doped magnetite magnetic nanoparticles (NPs) were prepared in aqueous solution (Series A) or in a water-ethyl alcohol mixture (Series B) by the co-precipitation method. Only one ferromagnetic resonance line was observed in all cases under consideration indicating that the materials are magnetically uniform. The shortfall in the resonance fields from 3.27 kOe (for the frequency of 9.5 GHz) expected for spheres can be understood taking into account the dipolar forces, magnetoelasticity, or magnetocrystalline anisotropy. All samples show non-zero low field absorption. For Series A samples the grain size decreases with an increase of the Zn content. In this case zero field absorption does not correlate with the changes of the grain size. For Series B samples the grain size and zero field absorption behavior correlate with each other. The highest zero-field absorption corresponded to 0.2 zinc concentration in both A and B series. High zero-field absorption of Fe3O4 ferrite magnetic NPs can be interesting for biomedical applications.
authors.affiliation: LAFMACEL, Fac. de Ingeniería, UBA, Paseo Colón 850, C1063EHA Buenos Aires, Argentina. caphestegu@fi.uba.ar.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Aphesteguy
authors.affiliation: LAFMACEL, Fac. de Ingeniería, UBA, Paseo Colón 850, C1063EHA Buenos Aires, Argentina. silviajacobo@gmail.com.
authors.forename: Silvia E
authors.initials: SE
authors.lastname: Jacobo
authors.affiliation: Depto. Química Inorgánica, Universidad del País Vasco UPV-EHU, 48940 Leioa, Spain. luis.lezama@ehu.es.
authors.forename: Luis
authors.initials: L
authors.lastname: Lezama
authors.affiliation: Depto. de Electricidad y Electronica, Universidad del País Vasco UPV-EHU, 48940 Leioa, Spain. galina@we.lc.ehu.es.
authors.forename: Galina V
authors.initials: GV
authors.lastname: Kurlyandskaya
authors.affiliation: Institute of Metal Physics UD RAS, 620041 Ekaterinburg, Russia.
authors.forename: Nina N
authors.initials: NN
authors.lastname: Schegoleva
mesh_terms: D016880:Anisotropy; D052203:Ferrosoferric Oxide; D058185:Magnetite Nanoparticles; D008872:Microwaves
chemical_list: D058185:Magnetite Nanoparticles; D052203:Ferrosoferric Oxide