| چکیده انگلیسی مقاله |
In recent years, there has been a significant interest in lanthanum-based perovskites due . Lanthanum strontium manganite (LSMO) is one of the most well-known materials. In this research, the synthesis and investigation of the effect of oleic acid on the structural and magnetic properties of La0.7Sr0.3MnO3 nanoparticles by the combustion sol-gel method is discussed. The structural and magnetic properties of the prepared samples were investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), magnetic properties analysis (VSM), and field emission electron microscopy (FESEM). In the XRD study, it was found that the crystal structure of the samples is hexagonal. Also, the average crystal size in the samples increased from 18 nm to about 33 nm as a result of adding oleic acid. The images obtained from FESEM show that the presence of oleic acid in the synthesis of nanoparticles caused it to affect the shape of the particles as a surface layer. Synthesized nanoparticles have a particle size between 20-100 nm, and with the increase of oleic acid, the particle size becomes more than 100 nm. FTIR spectroscopy revealed the effective bonding between LSMO nanoparticles and oleic acid, based on these results, it clearly shows the presence of oleic acid molecules on the surface of magnetic particles. In the investigation of magnetic properties, it was found that the presence of non-magnetic sodium oleate surface layer, which due to the addition of oleic acid on nanoparticles, the saturation magnetization value decreased from 38.55 emu/g to 28.46 emu/g.
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