Structure and magnetic properties of Gd x Y 1x FeO 3 obtained by mechanosynthesis A.M. Bolarín-Miró a , F. Sánchez-De Jesús a,⇑ , C.A. Cortés-Escobedo b , R. Valenzuela c , S. Ammar d a Área Académica de Ciencias de la Tierra y Materiales, Universidad Autónoma del Estado de Hidalgo Mineral de la Reforma, Hidalgo 42184, Mexico b Centro de Investigación e Innovación Tecnológica del IPN, Distrito Federal 02250, Mexico c Depto. de Materiales Metálicos y Cerámicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México D.F. 04510, Mexico d ITODYS, UMR 7086, Université de Paris-Diderot, 75250 Paris Cedex, France article info Article history: Available online 13 April 2013 Keywords: Mechanochemistry Orthoferrite Doped GdFeO 3 Doped YFeO 3 Mechanochemical processing abstract Solid solutions of yttrium–gadolinium orthoferrites Gd x Y 1x FeO 3 (0 6 x 6 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, Fe 2 O 3 ,Y 2 O 3 and Gd 2 O 3 , 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 orthorhom- bic 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 Gd 0.75 Y 0.25 FeO 3 . For Gd 0.5 Y 0.5 FeO 3 , the magnetization decreases down to 2.1 emu/g. A small contamination of metallic Fe was confirmed through electron spin resonance experiments. Ó 2013 Elsevier B.V. All rights reserved. 1. Introduction Ceramics with a perovskite structure have been a subject of interest for researchers due to their potential technological appli- cations [1,2]. In particular, yttrium orthoferrite, YFeO 3 , and its re- lated solid solutions (substituted orthoferrites) are among a wide variety of functional materials that are used in many electronic applications and are attractive materials for use in other applica- tions, such as in the memory elements of logic devices in computer engineering, as well as for use in catalysis, gas separation systems, cathodes of solid oxide fuel cells, sensors, magneto-optical sys- tems, magnetic field sensors and information recording and stor- age systems [2–5]. Rare earth orthoferrites, RFeO 3 , where R is the rare earth, crys- tallize in the perovskite structure [6], with the Fe 3+ ion surrounded by six oxygen ions in the B-sites [7] and with R in the A-sites. YFeO 3 , which is weakly ferromagnetic due to a canted antiferro- magnetic structure [8], presents a polymorphic behavior and crys- tallizes in either orthorhombic or hexagonal structures, depending on the synthesis conditions [9]. When magnetic Gd 3+ is partially substituted for non-magnetic Y 3+ in YFeO 3 , the generation of new magnetic interactions [10] and the ensuing changes in the material’s magnetic behavior are expected. The incorporation of a bigger cation, such as substituting Gd 3+ (ionic radii 0.938 Å) for Y +3 (ionic radii 0.90 Å) into the YFeO 3 structure in the A sites, increases the Goldschmidt’s tolerance fac- tor, presumably helping to induce variations in the lattice param- eters with respect to the Pbnm structure that is found at lower Gd 3+ concentrations. This structural change or distortion of the crystal structure should modify the magnetic behavior of the cera- mic [11]. To obtain orthoferrites, several synthesis methods have been developed [12–16]. The mechanochemical process (MCP) is an effective, economical and versatile way to produce RFeO 3 using powder oxide mixtures. The effectiveness of the high-energy ball milling technique to promote the mechanosynthesis of the nano- structured ferrites by the mechanical activation of oxide com- pounds has been shown to yield excellent results [17–20] for diverse types of orthoferrites, such as YFeO 3 [21], LaFeO 3 [22], La 1x Y x FeO 3 [11], Ca 1x La x FeO 3 [23] and Bi 1x Y x FeO 3 [24]. To the best of our knowledge, there are no references about the use of this technique to obtain solid solutions of Gd 1x Y x FeO 3 orthoferrites. Because in this process the magnetic ion is incorporated into the 0925-8388/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jallcom.2013.04.029 ⇑ Corresponding author. Tel.: +52 7717172000x2280. E-mail address: fsanchez@uaeh.edu.mx (F. Sánchez-De Jesús). Journal of Alloys and Compounds 586 (2014) S90–S94 Contents lists available at SciVerse ScienceDirect Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jalcom