Effect of different rare-earth elements substitution on microstructure and microwave absorbing properties of Ba0.9RE0.1Co2Fe16O27 (RE=La, Nd, Sm) particles

Rare-earth (RE) ions substituted W-type hexaferrite Ba0.9RE0.1Co2Fe16O27 (RE =La3+, Nd3+ Sm3+) were prepared by solid-state reaction method at 1250 degrees C for 5 h. The microstructure was investigated using the powder X-ray diffractometer and the scanning electron microscope. The results showed that rare-earth ions substituted barium ferrite was single phase of W-type, and appeared hexagonal platelet-like shape. The lattice parameters 'a' and 'c' decreased gradually with the decrease of rare-earth ionic radius. The complex permittivity and complex permeability in the range from 0.5 to 18.0 GHz were measured by vector network analyzer. The microwave absorption properties were characterized by tan delta, which was calculated using the formula of tan delta = tan delta(e) + tan delta(m). Furthermore, the reasons of those phenomenons were discussed using the interfacial polarization, intrinsic electric dipole polarization and ferromagnetic theory. (C) 2011 Elsevier B.V. All rights reserved.