Ferromagnetic properties of the Zn-Mn-O system.

Polycrystalline Zn-Mn-O samples with nominal manganese concentration x = 0.01 and 0.10 were synthesized by a solid state reaction route using (ZnC(2)O(4)·2H(2)O)(1-x) and (MnC(2)O(4)·2H(2)O)(x). Thermal treatment of the samples was carried out in air at temperatures of 673, 773 and 1173 K. The samples were investigated by x-ray diffraction, thermogravimetry, differential thermal analysis, transmission electron microscopy, magnetization measurements and electron paramagnetic resonance. Room temperature ferromagnetism is observed in Zn-Mn-O samples with x = 0.01 thermally treated at low temperatures (673, 773 K). It seems that the ferromagnetic phase could originate from interactions between Mn(2+) ions and acceptor defects incorporated in the ZnO crystal lattice during the thermal treatment of the samples.