A Neutron Diffraction Investigation of High Valent Doped Barium Ferrite With Super-wide Tunable Microwave Absorption

The Barium ferrite BaTixFe12-xO19 (x = 0.2, 0.4, 0.6, 0.8) ceramics doped by Ti4+ (BFTO-x) were synthesized by a modified sol-gel method. The crystal structure and magnetic structure of the samples were determined by neutron diffraction, and confirm that the BFTO-x ceramics were high quality single phase with sheet micro-structure. With x increasing from 0.2 to 0.8, the Ms decreases gradually but the change of Hc is complex under the synergy of the changed grain size and the magnetic crystal anisotropy field. Relying on the high valence of Ti4+, double resonance peaks are obtained in the curves of μ′′ and the resonance peaks could move towards the low frequency with the increase of x, which facilitate the samples perform an excellent wide-band modulation microwave absorption property. In the x = 0.2 sample, the maximum reflection loss can reach –44.9 dB at the thickness of only 1.8 mm, and the bandwidth could reach to 5.28 GHz at 2 mm when the RL is less than –10 dB. All the BFTO-x ceramics show excellent frequency modulation ability varying from 18 GHz (x = 0.8) to 4 GHz (x = 0.4), which covers 81% of the investigated frequency in microwave absorption field.