Study On The Properties Of Ru-doped CoFe₂O₄ And Co-Ru Co-doped SrFe₁₂O₁₉

Ferrite magnetic materials play an important role in production,life,military,medical treatment and other aspects.Changing the performance of ferrite materials can adapt them to more application scenarios.In this paper,ion doping,which is widely used in modification of ferrite,was selected as a method to change the performance.The following contents were completed:Powder samples CoFe_2-xRu_xO₄?x=0,0.1,0.3,0.5 and 0.7?with spinel structure were prepared by solid-state reaction,and measured the X-ray diffraction?XRD?,Fourier transform infrared?FT-IR?,ultraviolet-visible?UV-Vis?and hysteresis loops of the samples.XRD results show that the space group of the samples is Fd-3m.Combined with the results of FT-IR,it is inferred that Ru⁴⁺occupies the tetrahedral A sites in the spinel.UV-Vis results show that the band gaps gradually decrease from1.42 eV at x=0 to 1.08 eV at x=0.7,indicating that the doping of Ru⁴⁺introduced impurity energy level.The magnetic results at room temperature show that the saturation magnetization M_s of the sample decreases with the increase of Ru⁴⁺content.The residual magnetization M_r,the rectangular ratio M_r/M_s and the coercive force H_c first increase with the increase of Ru content,and then decrease after x=0.3.All three of them achieve the maximum value at x=0.3.Hysteresis loops at T=2K show that the saturation magnetization M_s is the largest when x=0.1,which is 103.15emu/g,The coercive force is the largest when x=0.5,which is 1541 Oe.SrFe_12-2xCo_xRu_xO₁₉?x=0.1,0.3,0.5,0.7,0.9,1.1 and 1.3?with the space group P6₃/mmc was synthesized by solid-state reaction.As x increases,the lattice parameters a increases and c decreases.This is because Co²⁺-Ru⁴⁺co-doping reduces the c-axis magnetocrystalline anisotropy.Combined with the analysis of FT-IR,it is speculated that Co²⁺ions are at the octahedral 2a and 4f₂ sites,most of Ru⁴⁺ions are at the tetrahedral 4f₁ sites with some at the octahedral 2a and 4f₂ sites.The UV-Vis results reflect the maximum band gap of the samples is 1.64 eV when x=0.Hysteresis loops at room temperature indicate that the residual magnetization and coercive force decrease with increasing x content.Co²⁺-Ru⁴⁺co-doping reduces the c-axis magnetocrystalline anisotropy.The saturation magnetization reaches the maximum value at x=0.3,which is 69.32 emu/g.In the range of 0 GHz-18 GHz,Co²⁺-Ru⁴⁺co-doping improves the microwave absorption performance of all SrFe_12-2xCo_xRu_xO₁₉ with x>0.1.In x=0.3,the minimum value of the reflection loss is RL=-57 dB with a wide bandwidth 5.4GHz,and the optimal absorption thickness is 3.7 mm In x=1.1,the bandwidth of reflection loss?RL?<-10 dB is broader than14.10 GHz of 3.90 GHz to>18 GHz.SrFe_12-2xCo_xRu_xO₁₉ shows good potential as a microwave absorption material,which provides a certain reference for future researches of microwave absorption materials improved by strontium ferrite.