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Structural and Magnetic Properties of Pure and Mn-Doped Bismuth Ferrite Powders Hector A. Chinchay Espino 1, Gina M. Montes-Albino 2, Christian O. Villa Santos3, Oscar J. Perales Perez4 1

Department of Physics, University of Puerto Rico, Mayaguez Campus, Mayaguez, PR, United States. 2 Department of Mechanical Engineering, University of Puerto Rico, Mayaguez Campus, Mayaguez, PR, United States. 3 Department of Chemical Engineering, University of Puerto Rico, Mayaguez Campus, Mayaguez, PR, United States. 4 Department of Engineering Sciences and Materials, University of Puerto Rico, Mayaguez Campus, Mayaguez, PR, United States. ABSTRACT Multiferroic materials are of great interest from the scientific and technological viewpoints based on their multifunctional behavior involving ferroelectricity, ferromagnetism, ferroelasticity and strong electromagnetic coupling properties. Among these materials, BiFeO3 (BFO), is a well-known multiferroic with simultaneous ferroelectricity (TC=1103K) and G-type antiferromagnetism (TN=643K). In this work, we doped BiFeO3 with Mn species and studied the doping effect on the corresponding magnetic properties, expected from the substitution of Bi3+ by Mn2+. Additionally, the optimum processing conditions to minimize the formation of any impurity phase were also identified. X-Ray Diffraction (XRD) characterization confirmed the formation of powdered impurity-free BFO in pure and 7 at.% Mn-BFO only after annealing of the precursor compounds at suitable temperatures and time (700°C, 15 minutes). Scanning Electron Microscopy (SEM) analyses were used to determine the size and morphology of synthetized powders. Vibrating sample magnetometry (VSM) measurements showed that maximum magnetization values increased with doping and reached a maximum value in the 7 at.% Mn-doped BFO annealed at 700°C for 15min; the corresponding magnetization in the nonsaturated MH loops reached 0.68 emu/g. This behavior can be attributed to the actual incorporation of Mn species into the BFO lattice and the substitution of non-magnetic Bi species. INTRODUCTION Multiferroic materials show a spontaneous, switchable internal alignment of electric charges in the case of ferroelectricity, spin alignment in the case of ferromagnetism, and strain alignment in ferroelasticity. The electromagnetic coupling allows tuning of ferroelectricity or ferromagnetism using either magnetic or electric field [1-2]. Bismuth ferrite (BiFeO3 or BFO) is undoubtedly one of the most intensively studied multiferroic material; it has a perovskite structure with an antiferromagnetic (Neel temperature of ~370 °C), and ferroelectric character with a Curie temperature of ~850°C. These properties make BFO an excellent candidate for applications in data storage, spintronic, electronic devices, and solar energy devices [3-5]. Hydrothermal [6], sol-gel [4, 7, 8], solid state [9], and other methods have been used to synthetize BFO powders. Sol-gel is the most used method for synthesis of BFO nanosize powders, because it is easy, inexpensive, and highly re