Facile synthesis of Ca-doped manganite nanoparticles by a nonaqueous sol–gel method and their magnetic properties

Perovskite manganite La1−xCaxMnO3 (x=1/3x=1/3, 1/2 and 2/3) nanoparticles with the average particle size of about 20 nm have been synthesized by a facile nonaqueous sol–gel method using methanol as a solvent and characterized by X-ray diffraction, transmission electron microscopy and superconducting quantum interference device magnetometer. Magnetic measurements reveal that although their bulk counterparts have quite different magnetic ground states, the three-nanosized samples exhibit similar ferromagnetic behaviors below about 270 K. This result implies that with the particle size reduced to nanoscale, the ferromagnetism for x=1/3x=1/3 is weaken, while it is enhanced, accompanied by the suppression of the charge ordering, for x=1/2x=1/2 and 2/3. Moreover, the exchange bias phenomena are observed in the two latter nanoparticles, which is of special interest for potential applications.