Ferromagnetic behaviour of the Zn-Mn-O system

Abstract

Polycrystalline Zn-Mn-O samples with nominal manganese concentrations x = 0.0 1, 0.04 and 0.10 were synthesized by a solid state reaction route using (ZnC(2)O(4 center dot)2H(2)O)(1-x) and (MnC(2)O(4)-2H(2)O)(x). Thermal treatment of the samples was performed in air at temperatures 673, 773, 873, 973 and 1173 K for x = 0.01 and at the temperature 773 K for x = 0.04 and 0.10. The samples were investigated by X-ray diffraction, thermogravimetry, differential thermal analysis, transmission electron microscopy, magnetization measurements and electron paramagnetic resonance. X-Ray diffraction was also performed on MnO(2) thermally treated at temperatures 673, 773, 873, 973, 1073 and 1173 K. Room temperature ferromagnetism was observed in the Zn-Mn-O samples with x = 0.0 1 thermally treated at low temperatures (673 and 773 K) and in the sample with x = 0.04 thermally treated at 773 K. It seems that the ferromagnetic phase could originate from interactions between Mn(2+) and acceptor defects incorporated in the ZnO crystal lattice during the thermal treatment of the samples.