Electromagnetic properties and microwave absorption of W-type hexagonal ferrites doped with La 3+

Abstract

W-type barium hexaferrites with compositions of Ba 1Co 0.9Zn 1.1Fe 16O 27 and Ba 0.8La 0.2Co 0.9Zn 1.1Fe 16O 27 were synthesized by the sol–gel method. The electromagnetic properties and microwave absorption behavior of these two ferrites were studied in the 2–18 GHz frequency range. The microstructure and morphology of the ferrites were characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM) techniques. The complex permittivity spectra, the complex permeability spectra and microwave reflection loss were measured by a microwave vector network analyzer. The XRD patterns show that the main phase of the Co 2W ferrite forms without other intermediate phases when calcined at 1200 °C. The SEM images indicate that flake-like hexagonal crystals distribute uniformly in the materials. Both the magnetic and dielectric losses are significantly enhanced by partial substitution of La 3+ for Ba 2+ in the W-type barium hexaferrites. The microwave absorption property of the La 3+ doping W-type hexaferrite sample is enhanced with the bandwidth below −10 dB around 8 GHz and the peak value of reflection loss about −39.6 dB at the layer thickness of 2 mm.