Abstract
The barium ferrite BaTixFe12−xO19 (x = 0.2, 0.4, 0.6, 0.8) (BFTO-x) ceramics doped by Ti4+ 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 microstructure. With x increasing from 0.2 to 0.8, the saturation magnetization (Ms) decreases gradually but the change trend of coercivity (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 the imaginary part of magnetic conductivity (μ″) and the resonance peaks could move toward the low frequency with the increase of x, which facilitate the samples perform an excellent wideband modulation microwave absorption property. In the x = 0.2 sample, the maximum reflection loss (RL) can reach −44.9 dB at the thickness of only 1.8 mm, and the bandwidth could reach 5.28 GHz at 2 mm when RL is less than −10 dB. All the BFTO-x ceramics show excellent frequency modulation ability varying from 18 (x = 0.8) to 4 GHz (x = 0.4), which covers 81% of the investigated frequency in microwave absorption field. This work not only implements the tunable of electromagnetic parameters but also broadens the application of high-performance microwave absorption devices.
Highlights
The rapid development of electronic informationJ Adv Ceram 2022, 11(2): 263–272reflection loss (RL) and broadening the effective bandwidth [4,5,6]
The powder mixed with polyvinyl alcohol (PVA) was pressed into wafers of 13 mm in diameter and sintered at 600 °C for 4 h to eliminate the binder, and the wafers were sintered at 1200 °C for 4 h in air atmosphere to obtain the BFTO-x ceramics
The neutron diffraction patterns of BFTO-x (x = 0.2, 0.4, 0.6, 0.8) ceramics are shown in Fig. 1(a), which contains the complete neutron diffraction pattern before and after refinement using Rietveld method
Summary
RL and broadening the effective bandwidth [4,5,6]. The microwave absorption materials can be classified into a resistive type, a dielectric type, and a magnetic medium type according to the loss mechanism [7,8,9]. The attenuation of the electromagnetic wave by the magnetic medium type absorbing materials mainly comes from resonance and hysteresis loss, such as ferrite and carbonyl iron [12,13]. Among all these materials, the ferrite is an ideal microwave absorbing material for the simple preparation process and the stable performance [14,15,16]. M-type barium ferrite (BaFe12O19, abbreviated as BaM), a versatile material, performs excellent electromagnetic properties due to the large magnetic loss at the natural resonance frequency. The modified M-type barium ferrite exhibits better tunability for electromagnetic properties, which has a positive role on the exploration of the novel microwave absorbing materials
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