High-frequency absorption properties of gallium weakly doped barium hexaferrites

Abstract

ABSTRACTThe BaFe12-xGaxO19 (x < 1.2) hexaferrites were synthesised by usual ceramics technology. The Bi2O3 additive in the amount of 3 wt% was applied. The features of crystal structure and unit cell parameters were refined using powder X-ray diffraction at 300 K. It is shown that with the substitution level increase the parameters of unit cell monotonically decrease. The magnetisation and susceptibility versus temperature and field for these solid solutions were investigated by the vibration magnetometry method. The concentration dependence of the main magnetic parameters is constructed. It is shown that with the substitution level increase the magnetic parameters monotonically decrease. The microwave properties of the samples including the external magnetic bias field are also investigated at 300 K. It is shown that with the increase of Ga3+ concentration from x = 0.1 to x = 0.6 the frequency value of natural ferromagnetic resonance (NFR) decreases in the beginning, and at further increase in concentration up to x = 1.2 it increases again. With the increase in Ga3+ concentration, the line width of the NFR increases that indicates the increase of frequency range where there is an intensive absorption of electromagnetic radiation (EMR). At the same time, the peak amplitude of the resonant curve changes slightly. The frequency shift of NFR in the external magnetic bias field takes place more intensively for the samples with small Ga3+ concentration. It is shown the prospects of use of the Ga-substituted barium hexagonal ferrite as the material effectively absorbing the high-frequency EMR.