Distinct magnetic response of nanograined Zn1−xMnxO (x = 0, 0.02, 0.1) powders and thin films: Focus on the effect of the working atmosphere

► Nanocrystalline ZnO powders and thin films have successfully be produced. ► Wet chemistry method is used to synthesize the ZnO nanopowders. ► ZnO nanoowders show no ferromagnetic signal. ► Collective magnetism in ZnO films seems to be induced by vacancies. ► Only sufficiently high concentrations of vacancies may lead to an FM phase.