Synthesis, structure and magnetic properties of nanostructured La1−xAxFe0.5Mn0.5O3 (A = Ca, Sr and Pb; x = 0 & 0.25) perovskites

The effect of hole doping on magnetic properties of LaFe0.5Mn0.5O3 have been investigated. All the ceramics samples La1−xAxFe0.5Mn0.5O3 (A = Ca, Sr and Pb; x = 0 & 0.25) were synthesized at 500 °C by sol-gel method and the particles size were found to be in nanodimension. The samples were characterized by X-ray and electron diffraction, HRTEM and both dc and ac-magnetization measurements. The X-ray and electron diffraction patterns were indexed by cubic Pm-3m space group. The particle size of the LaFe0.5Mn0.5O3 is ∼100 nm, whereas the Pb-doped sample is ∼50 nm and for Ca or Sr doped samples the size is ∼10-30 nm. Both dc and ac-susceptibility measurements suggest that the effect of hole doping and A-site cationic radius in LaFe0.5Mn0.5O3 have no significant role on magnetic properties. However, the particle size plays an important role on magnetic property due to the development of surface ferromagnetic cluster at nanoscale. The competing interactions lead to magnetic phase separation where local ferromagnetic clusters coexist within the antiferromagentic matrix in all the samples.