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Col. Bosques de las Lomas, Mexico

Sanchez-De Jesus F.,Autonomous University of the State of Hidalgo | Cortes C.A.,Research Center e Innovacion Tecnologica del | Valenzuela R.,National Autonomous University of Mexico | Ammar S.,University Paris Diderot | Bolarin-Miro A.M.,Autonomous University of the State of Hidalgo
Ceramics International | Year: 2012

Yttrium iron garnet, Y 3Fe 5O 12 (YIG) powders were synthesized by mechanochemical processing (MCP) from Fe 2O 3 and Y 2O 3, followed by an annealing. The aim of this work was to demonstrate that MCP followed by annealing at relative low temperatures can induce the formation of nanostructured YIG. The effect of synthesis process on the final magnetic properties was also studied. The precursors mixed in a stoichiometric ratio to obtain YIG were milled at room temperature in a shaker mixer mill with a ball:powder weight ratio of 10:1. In order to achieve a single-phase of nanostructured YIG a short thermal annealing at temperatures from 700 to 1100°C was done. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the synthesized powders. The milling process promotes the formation of a perovskite phase (orthoferrite YFeO 3) independent from the milling time; garnet could only be obtained after an annealing process. The partial formation of the garnet phase was observed in mixtures milled for 5 h. In order to obtain a pure YIG, it is necessary to do a post-treatment of an annealing at temperatures of 900°C, around 400°C lower than those used to prepare the material by solid state reaction. Also, the effect of synthesis method into the magnetic behavior of the garnet was shown. © 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Source


Sanchez-De Jesus F.,Autonomous University of the State of Hidalgo | Bolarin-Miro A.M.,Autonomous University of the State of Hidalgo | Cortes-Escobedo C.A.,Research Center e Innovacion Tecnologica del | Valenzuela R.,National Autonomous University of Mexico | Ammar S.,University Paris Diderot
Ceramics International | Year: 2014

M-type strontium hexaferrite was prepared by mechanosynthesis using high-energy ball milling. The influence of milling parameters, hematite excess and annealing temperature on magnetic properties of SrFe12O 19 were investigated. Commercial iron and strontium oxides were used as starting materials. It was found that mechanical milling followed by an annealing treatment at low temperature (700 C) promotes the complete structural transformation to Sr-hexaferrite phase. For samples annealed at temperatures from 700 to 1000 C, saturation magnetization values (Ms) are more sensitive to annealing temperature than coercivity values (Hc). The maximum Ms of 60 emu/g and Hc of 5.2 kOe were obtained in mixtures of powders milled for 5 h and subsequently annealed at 700 C. An increase in the annealing temperature produces negligible changes in magnetic saturation and coercivity. An excess of hematite as a second phase produces a slight decrease in the saturation magnetization but leads to a significant increase in coercive field, reaching 6.6 kOe. © 2013 Elsevier Ltd and Techna Group S.r.l. Source


Bolarin-Miro A.M.,Autonomous University of the State of Hidalgo | Sanchez-De Jesus F.,Autonomous University of the State of Hidalgo | Cortes-Escobedo C.A.,Research Center e Innovacion Tecnologica del | Valenzuela R.,National Autonomous University of Mexico | Ammar S.,University Paris Diderot
Journal of Alloys and Compounds | Year: 2014

Solid solutions of yttrium-gadolinium orthoferrites GdxY 1-xFeO3 (0 ≤ x ≤ 1) were prepared by high-energy ball milling. The aim of this work was to study the influence of the synthesis parameters on the crystal structure and the magnetic behavior of these solid solutions. The precursors, Fe2O3, Y 2O3 and Gd2O3, mixed in a stoichiometric ratio to obtain these orthoferrites, were milled for different times (up to 5 h). X-ray diffraction and Rietveld refinement were used to elucidate the phase transformation as a function of the milling time. Results showed the complete formation of orthoferrite with an orthorhombic structure (S.G. Pbnm) without any annealing after 5 h of milling for all of the compositions. The effect of the synthesis process and the x value on the crystal structure and the magnetic properties were also studied. All of the synthesized powders demonstrated weak ferromagnetic behavior. In particular, an increase in the maximum magnetization for all the compositions was found, with a maximum that reached 7.7 emu/g for Gd0.75Y0.25FeO3. For Gd0.5Y0.5FeO3, the magnetization decreases down to 2.1 emu/g. A small contamination of metallic Fe was confirmed through electron spin resonance experiments. © 2012 Elsevier B.V. All rights reserved. Source


Sanchez-De Jesus F.,Area Academica de Ciencias de la Tierra y Materiales | Bolarin-Miro A.M.,Area Academica de Ciencias de la Tierra y Materiales | Torres-Villasenor G.,National Autonomous University of Mexico | Cortes-Escobedo C.A.,Research Center e Innovacion Tecnologica del | Betancourt-Cantera J.A.,Area Academica de Ciencias de la Tierra y Materiales
Journal of Materials Science: Materials in Medicine | Year: 2010

We report on an alternative route for the synthesis of crystalline Co-28Cr-6Mo alloy, which could be used for surgical implants. Co, Cr and Mo elemental powders, mixed in an adequate weight relation according to ISO Standard 58342-4 (ISO, 1996), were used for the mechanical alloying (MA) of nano-structured Co-alloy. The process was carried out at room temperature in a shaker mixer mill using hardened steel balls and vials as milling media, with a 1:8 ball:powder weight ratio. Crystalline structure characterization of milled powders was carried out by X-ray diffraction in order to analyze the phase transformations as a function of milling time. The aim of this work was to evaluate the alloying mechanism involved in the mechanical alloying of Co-28Cr-6Mo alloy. The evolution of the phase transformations with milling time is reported for each mixture. Results showed that the resultant alloy is a Co-alpha solid solution, successfully obtained by mechanical alloying after a total of 10 h of milling time: first Cr and Mo are mechanically prealloyed for 7 h, and then Co is mixed in for 3 h. In addition, different methods of premixing were studied. The particle size of the powders is reduced with increasing milling time, reaching about 5 μm at 10 h; a longer time promotes the formation of aggregates. The morphology and crystal structure of milled powders as a function of milling time were analyzed by scanning electron microscopy and XR diffraction. © 2010 Springer Science+Business Media, LLC. Source


Bolarin-Miro A.M.,Autonomous University of the State of Hidalgo | Vera-Serna P.,Autonomous University of the State of Hidalgo | Sanchez-De Jesus F.,Autonomous University of the State of Hidalgo | Cortes-Escobedo C.A.,Research Center e Innovacion Tecnologica del | Martinez-Luevanos A.,Autonomous University of Coahuila
Journal of Materials Science: Materials in Electronics | Year: 2011

Manganese ferrites, MnFe 2O 4±δ, synthesized via mechanosynthesis from different manganese sources, MnO, Mn 2O 3 and MnO 2, and mixed with Fe 2O 3, were studied. XRD, SEM and magnetometry were used to characterize the synthesized powders. The MnFe 2O 4 spinel phase appeared after 12 h of milling when MnO and MnO 2 mixed with Fe 2O 3 were used as the precursors and showed the maximum saturation magnetization value (49.77 emu/g). Manganese ferrite did not form when MnO 2 was used. Manganese ferrite obtained from Mn 2O 3 showed the lowest saturation magnetization value. An increase in the milling time promoted the increase in the saturation magnetization values. © 2010 Springer Science+Business Media, LLC. Source

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