%0 Journal Article
%A Cobos Fernández, Miguel Ángel
%A Presa Muñoz De Toro, Patricia Marcela De La
%A Llorente, I.
%A Alonso Rodríguez, José María
%A Garcia Escorial, A.
%A Marín Palacios, María Pilar
%A Hernando Grande, Antonio
%A Jiménez, J. A.
%T Magnetic phase diagram of nanostructured zinc ferrite as a function of inversion degree delta
%D 2019
%@ 1932-7447
%U https://hdl.handle.net/20.500.14352/13645
%X Magnetic properties of spinel zinc ferrites are strongly linked to the synthesis method and the processing route since they control the microstructure of the resulting material. In this work, ZnFe_2O_4 nanoparticles were synthesized by the mechanochemical reaction of stoichiometric ZnO and alpha-Fe2O3, and single-phase ZnFe_2O_4  was obtained after 150 h of milling. The as-milled samples, with a high inversion degree, were subjected to different thermal annealings up to 600 ºC to control the inversion degree and, consequently, the magnetic properties. The as-milled samples, with a crystallite size of 11 nm and inversion degree delta = 0.57, showed ferrimagnetic behavior even above room temperature, as shown by Rietveld refinements of the X-ray diffraction pattern and superconducting quantum interference device magnetometry. The successive thermal treatments at 300, 400, 500, and 600 degrees C decrease delta from 0.15 to 0.18, affecting the magnetic properties. A magnetic phase diagram as a function of delta can be inferred from the results: for delta < 0.25, antiferromagnetism, ferrimagnetism, and spin frustration were observed to coexist; for 0.25 < delta < 0.5, the ferrimagnetic clusters coalesced and spin glass behavior vanished, with only a pure ferrimagnetic phase with a maximum magnetization of M_s = 3.5 mu_B remaining. Finally, for delta > 0.5, a new antiferromagnetic order appeared due to the overpopulation of nonmagnetic Zn on octahedral sites that leads to equally distributed magnetic cations in octahedral and tetrahedral sites.
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