Abstract
Co-doped ZnO samples with above-room-temperature Curie point were fabricated by the standard solid-state reaction method. Ferromagnetic behavior varied with different quenching temperatures ranging from 1173 K to 573 K after calcination. Extensive analyses on structural and composition revealed that cobalt is homogeneously incorporated into the ZnO lattice forming solid solution instead of precipitation when x≤ 0.02 in Zn 1-x Co x O. In the case of Zn 0.98 Co 0.02 O, ferromagnetism was enhanced by decreasing the quenching temperature until 573 K. The coercive field measured by a vibrating sample magnetometer (VSM) at room temperature is around 60-80 Oe. The implication of the effect of quenching temperature in bulk Zn 0.98 Co 0.20 is also discussed. © 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.