The Microwave Absorbing Performance of Co2+ - Ti4+ Co-doped Barium Ferrite Ceramics

M-type barium ferrite BaFe12O19 (BaM) is widely used in magnetic recording and microwave absorbing and doped BaM generally has a better performance on microwave absorbing property. The magnetic performance and microwave absorbing property for doped barium ferrite $\mathbf{Ba}(\mathbf{CoTi})_{\boldsymbol{x}}\mathbf{Fe}_{12-2\boldsymbol{x}}\mathbf{O}_{19}\ (\boldsymbol{x}=0.2,\ 0.4,\ 0.6)$ synthesized by sol-gel method are investigated in this work. With the increase of doping amount, the $\boldsymbol{M}_{\mathbf{r}}$ and $\boldsymbol{H}_{\mathbf{c}}$ decrease rapidly which may be attributed to the doping of Co²⁺ and Ti⁴⁺ ions decreases the magnetic and the magnetic anisotropy constant quickly. The microwave absorbing results show that the property of reflection loss can be modulated by thickness. The maximum reflection loss of absorber Ba(CoTi)0.4Fe11.2O19-PVA can reach −36.37 dB at 15.44 GHz at 4.5 mm with a bandwidth over −-10 dB 2.08 GHz while Ba(CoTi)0.6Fe10.8O19-PVA can reach −29.51 dB at 17.92 GHz at 3.6 mm.