Characteristics of magnetic properties of substituted hexagonal ferrites

The samples of barium hexaferrite BaFe 12-2x (Me 1 Me 2 ) x O 19 with x from 0.0 to 0.6 were prepared by variousmethods. The cationic preference of mainly divalent Me 1 = Zn, Co, Ni, Sn ions and tetravalent Me 2 = Ti, Zr, Ir, Sn, Ru ionsand their combinations in substituted Ba ferrites was investigated. The substitutions were performed to reduce the grain sizeand high magnetic uniaxial anisotropy field of the M-type Ba ferrite without affecting the magnetic polarisation. The goal isto reach the properties of ferrite proper for high-density magnetic recording and microwave absorption devices. Magneticproperties were determined as a function of the substitution level x. The specific saturation magnetic polarisation Js–m andremanence Js–rincreased with small x due to the substitution of non-magnetic and less magnetic ions in 4f 1 and 4f 2 sites. Thesteep decrease of coercivity Hc with increasing x may be caused by the Co 2+ preference of 4f 2 site and Ti 4+ or Zr 4+ ions preference of 2b and slightly in 4f 1 sites. The temperature coefficient of the coercivity TKHc was very low (0.01kA.m -1 .°C -1 )for the Co-Zr substitutions and positive for the rest of samples.