Hyperfine Interact (2008) 184:135–141 DOI 10.1007/s10751-008-9778-6 (Ni, Zn, Sn) Ru and (Ni, Sn) Sn substituted barium ferrite prepared by mechanical alloying A. González-Angeles · J. Lipka · A. Grusková · V. Jan ˇ cárik · I. Tóth · J. Sláma Published online: 5 October 2008 © Springer Science + Business Media B.V. 2008 Abstract NiRu, ZnRu, SnRu and SnSn mixtures considerably improved the satura- tion magnetization, M s with low substitution values; diminishing quickly at the same times the coercivity, H ci to suitable values for high-density magnetic recording appli- cations. On the other hand, the NiSn mixture also decreased the coercivity rapidly however without enhancing the saturation magnetization. The shown differences on magnetic properties were mainly due both to magnetic nature of divalent ion and to secondary phase apparitions. The mixtures with Sn 2+ as partner ion diminished markedly to T c . The tetravalent Ru 4+ ion has a special effect on magnetic properties of hexagonal ferrites (increases M s and diminishes fast H ci with low substitutions). Keywords Magnetic materials · Magnetic properties · Nanocrystalline materials PACS 75.50.-y · 75.75.+a · 81.07.Bc 1 Introduction Nowadays, the development of microwave communications technology and the need for anti-electromagnetic interference coatings has induced to an intense study of elec- tromagnetic wave absorbing materials in last years [1]. The most studied materials have been ferrites with spinel, garnet and hexagonal structure. Barium hexagonal ferrite is anisotropic and has a larger intrinsic magneto-crystalline anisotropy field. Because of their anisotropic plane, the natural resonance occurs in GHz range A. González-Angeles (B ) Facultad de Ingenieria, Universidad Autónoma de Baja California, Blvd. Benito Juárez s/n, Cp 21280, Mexicali, B. C., México e-mail: gangelesa@yahoo.com.mx J. Lipka · A. Grusková · V. Janˇ cárik · I. Tóth · J. Sláma Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovi ˇ cova 3, 81219 Bratislava, Slovak Republic