Structural and Magnetic Properties of Nano Manganite La_0.6Sr_0.4MnO₃ Obtained by Mechanochemical Synthesis Influenced by Preparation Conditions

Single phase La 0.6 Sr 0.4 MnO 3 nanoparticles with perovskite structure ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="normal">R</mml:mi> <mml:mover accent="true"> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> <mml:mo>̅</mml:mo> </mml:mover> <mml:mi mathvariant="normal">C</mml:mi> </mml:math> symmetry) were successfully prepared by ball milling (mechanochemical synthesis) for 1 and 10 h followed by annealing treatment at temperature 900 or 1100 °C. It was found that, the lattice parameters increase with the increase of milling time or annealing temperature. The increase of the annealing temperature results in the increase of crystallite size and the particle size. The obtained samples were found to be ferromagnetic at room temperature. The sample obtained by one hour of milling and 900 °C annealing showed high value of saturation magnetization (about 56 emu g −1 ) and small value of coercivity (about 31 Oe) at room temperature, while the other samples show reduced value of magnetization and higher value of coercivity. The obtained magnetic results are discussed in light of the core/shell model of nanoparticles. The effect of the presence of oxygen vacancies on the lattice parameters and magnetic properties of the obtained samples is also discussed.