La0.7Ca0.3MnO3 perovskite synthesized by reactive milling method: The effect of particle size on the magnetic and electrical properties

Nanocrystalline samples of La0.7Ca0.3MnO3 were synthesized by reactive milling method and annealed at various temperatures. Effect of particle size on the magnetic and electrical properties was investigated. While the ferromagnetic–paramagnetic transition temperature TC does not show significant change, metal–insulator TMI is markedly affected by particle size. Experimental data indicates linear relationship of magnetization and resistivity to the surface/volume ratio of the particles with different mean sizes. A phenomenological model, describing competition between the FM and PI phases used to elucidate temperature dependence of the resistivity with and without magnetic field, agrees quantitatively with experimental observations.