Synthesis and characterization of manganese-copper spinel ferrite powders

Magnetic Mn _1-xCu _xFe ₂O ₄(x=0.2, 0.5, 0.8 and 1.0) nanoparticles were synthesized by single citrate precursor method. The samples were characterized by powder X-ray diffraction, vibrating sample magnetometry and electron paramagnetic resonance(EPR). For samples with a low copper content(x<0.5), the copper ions have a tendency to occupy and substitute the Fe ³⁺ at the tetrahedral(A) sites. For samples with a high copper content(x>0.5), most Cu ²⁺ enter into the octahedral(B) sites. Transfer of Fe ³⁺ from octahedral sites to tetrahedral sites leads to the decrease of the saturation magnetization. Maximum coercivity is observed for CuFe ₂O ₄, nanoparticles due to the strengthened magnetic anisotropy arisen from the Jahn-Teller effect of the octahedral copper ions. The dependence of magnetic properties of Mn _0.8Cu _0.2Fe ₂O ₄ nanoparticles on calcination temperature was investigated. The cation distribution in Mn _0.8Cu _0.2Fe ₂O ₄ is sensitive to the calcination temperature.