Structural, EPR and optical properties of Zn0.75TM0.25O (TM = Mn, Fe, Co, Ni) aerogel nanoparticlesAmor Sayari, Lassaad El Mir and Hans Jürgen von BardelebenEur. Phys. J. Appl. Phys., 67 1 (2014) 10401DOI: https://doi.org/10.1051/epjap/2014140074