Preparation and microwave properties of Co- and Ti-doped barium ferrite by citrate sol–gel process

The citrate sol–gel synthesis method has been used to prepare Ba(CoTi)xFe12−2xO19 (x varies from 0.2 to 1.0 in steps of 0.2) hexaferrites. Several methods such as X-ray diffractometry, scanning electron microscopy (SEM) and network analyzer (HP8753E) have been used to obtain detailed information on the crystallography and microwave properties of the precursor powders calcined at different temperature. The correlations of Co2+Ti4+ substitution, annealing temperature and frequency with complex permeability, permittivity, microwave absorption of Ba(CoTi)xFe12−2xO19 ferrites have been studied. All the ferrites annealed at 1100 and 1200 °C exhibit significant dispersion in complex permeability. The dispersion in complex dielectric constant is significant for the samples sintered at 1200 and 1100 °C. The variations of reflection loss have been studied as a function of frequency, Co2+Ti4+ content, and thickness of the absorber.