Abstract

CAMPILLO FIGUEROA, Gloria et al. INFLUENCE OF BALL MILLING PROCESS ON STRUCTURAL AND MAGNETIC PROPERTIES OF La_0.7Sr_0.3MnO₃ MANGANITE. Rev.EIA.Esc.Ing.Antioq [online]. 2014, n.spe1, pp.31-38. ISSN 1794-1237.

This investigation presents the magnetic and structural properties of ferromagnetic manganite La_0.7Sr_0.3MnO₃, (LSMO), subjected to ball milling processes. The LSMO powder sample was obtained by solid state reaction from high purity precursors. From X-ray diffraction (XRD), the sample showed the characteristic peaks of this phase. By means of thermogravimetric analysis (TGA) assisted by magnetic field, used as first method to measure the Curie temperature TC, the NM (non-milling) LSMO powders exhibited a TC=369.69 K (96.96 oC), which agrees with the magnetization measurements. In order to study size dependent properties, LSMO powder was subjected to mechanical milling processes during 3, 6 and 12 hours. From Rietveld refinement of XRD patterns, a reduction in crystallite average size (Dv) and a stabilization of crystalline structure (the R3c space group), with milling time (tM), were observed. These results are consistent with the Scanning Electron Microscopy (SEM) images, which showed more homogeneity in the grain distribution with longer milling times. From magnetic characterization results, it was found that the saturation magnetization decreases with decreasing grain size (smaller Dv). This behavior is attributed to surface effects that induce magnetically disordered states in smaller particle sizes. However, the TC is kept constant around 365 K and it is independent of tM.

Keywords : Manganites; Colossal Magnetoresistance; Nanoparticles; Magnetic Properties.

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