Magnetism of Zn0.98Co0.02O nanopowders

We prepared Zn0.98Co0.02O nanopowders by conventional sol-gel method. The powders were sintered at different temperatures. The X-ray diffraction patters showed only wurtzite structure without any impurity phase, better crystalline structure and larger grain size with higher sintering temperature. The magnetic measurements showed that all the powders exhibited paramagnetism with weak antiferromagnetic exchange interaction. The quenched magnetic moment of Co ions was attributed to the weak antiferromagnetic exchange interaction between single Co ions and the antiparallel spin alignment of neighboring aggregated Co ions.