1 MECHANOCHEMICALLY ASSISTED SYNTHESIS OF YTTRIUM-LANTHANUM ORTHOFERRITE: STRUCTURAL AND MAGNETIC CHARACTERIZATION A.A. Cristóbal 1 , P.M. Botta 1* , P.G. Bercoff 2 , E.F. Aglietti 3 , H.R. Bertorello 2 and J.M. Porto López 1 1 Instituto de Investigaciones en Ciencia y Tecnología de Materiales (INTEMA), CONICET-UNMdP. J B Justo 4302 (B7608FDQ) Mar del Plata, Argentina. 2 Facultad de Matemática, Astronomía y Física (FaMAF), UNC, Ciudad Universitaria (5000) Córdoba, Argentina. IFEG, CONICET. 3 Centro de Tecnología de Recursos Minerales y Cerámica (CETMIC), CIC-CONICET. Camino Centenario y 506 (B1897ZCA) Gonnet, Argentina Abstract Polycrystalline Y 0.5 La 0.5 FeO 3 powder was synthesized by mechanochemical activation of Fe 3 O 4 - La 2 O 3 -Y 2 O 3 reactive mixtures. X-ray diffraction was used to follow the evolution of the formation of this orthoferrite. Peaks corresponding to reactants were no longer observed after 3h of activation, showing the completion of the reaction after this time. Magnetic hysteresis loops measured at room temperature revealed a gradual decrease of saturation magnetization, consistent with the consumption of ferrimagnetic Fe 3 O 4 and the formation of antiferromagnetic Y 0.5 La 0.5 FeO 3 . However, a small ferromagnetic contribution was observed even after 3 h of milling, which can be attributed to a canting in the alignment of the two sub-lattices in the orthoferrite structure. This uncompensated antiferromagnetism disappeared when the solid was heated, giving rise to a nearly antiferromagnetic structure. Keywords: A. magnetically ordered materials, B. mechanochemical processing, D. magnetic measurements * To whom correspondence should be addressed.