Synthesis of magnetoresistive La_(0.7)Sr_(0.3)MnO_3 nanoparticles by an improved chemical coprecipitation method

摘要

La_(0.7)Sr_(0.3)MnO_3 nanoparticles were prepared by a simple chemical coprecipitation route. Structural, magnetoresistance (MR), and magnetic properties were investigated. Rietveld refinement of X-ray powder diffraction result shows that the sample is single-phase with the space group of R3C. The result of field-emission scanning electronic microscopy shows that most of the grain sizes are distributed from 50 to 200 nm. The composition determined by energy-dispersive spectroscopy is the stoichiometry of La_(0.7)Sr_(0.3)MnO_3. The ferromagnetic to paramagnetic transition is sharp with Curie temperature T_C = 367 K, which further confirms that the sample is single-phase. The steep change in MR at low fields is attributed to the alignment of the magnetization, while the high-field MR is due to the grain boundary effect.