Study On The Properties Of Sn-Ni And Sn-Zn Co-doped SrFe₁₂O₁₉ And Fe,Mn,Cu,Ni Doped La₂CoMO₆

In this paper,the effects of Sn-Ni and Sn-Zn ions replacing SrFe₁₂O₁₉and Adding Fe,Cu,Mn and Ni ions on the structure,magnetic properties,optical properties and absorbing properties of double perovskite were studied,and the results are as follows:SrFe_12-2xSn_xNi_xO₁₉（x=0.1,0.3,0.5,0.7,0.9）samples were prepared by sol-gel method.By analyzing XRD images,it can be seen that the generated samples x=0.1,0.3,0.5,0.7,0.9 are single phase.When x=1.1,Fe₂O₃impurities will appear at31.5°.The improved experimental method can not eliminate the impurities,which is because the solution limit of the sample has reached.The coercivity and saturation magnetization decrease with the increase of Sn-Ni ion replacing SrFe₁₂O₁₉.Because Sn⁴⁺-Ni²⁺occupies the Fe³⁺crystal position which determines the magnetization of the lattice preferentially,and the magnetic moment after Replacing Fe³⁺by Ni²⁺is2μ_B,less than 5μ_B of Fe³⁺magnetic moment.Sn⁴⁺-Ni²⁺co-doped SrFe_12-2xSn_xNi_xO_19,with the increase of doping amount,the absorption performance is constantly improved.When the doping content is x=0.9 and the thickness is 2.5mm,the widest absorption band with RL<-10d B is in the range of 10.46GHz-14.07GHz.In the frequency range of 10.2GHz-15.1GHz,the reflection loss of samples in the thickness range of 2.5mm-4.5mm is less than-10d B.Sn-Ni doping can improve the microwave absorption of strontium ferrite.In order to further explore the effect of doping ions on the microwave absorption performance of strontium ferrite,Sn-Zn ion doped strontium ferrite was studied as a control experiment.SrFe_12-2xSn_xZn_xO₁₉（x=0.1,0.3,0.5,0.7,0.9,1.1）was prepared by sol-gel method.XRD analysis shows that the samples are all single phase and the crystal space group structure is hexagonal ferrite.Sn⁴⁺-Zn²⁺replaces Fe³⁺,and lattice parameters A,C and cell volume V increase gradually when doping amount x=0.1,0.3,0.5,0.7,0.9.The saturation magnetization of the sample increases with the increase of doping amount,because the magnetic moment increases when Sn-Zn ion replaces Fe ion.In terms of magnetic loss,when doping amount x=0.9,the virtual part of permeability（）increases significantly with frequency.In terms of dielectric loss,there is no obvious change,so the main loss mode of SrFe_12-2xSn_xZn_xO₁₉is magnetic loss.The absorption performance of Sn⁴⁺-Zn²⁺co-doped SrFe_12-2xSn_xZn_xO₁₉improved with the increase of doping amount.When x=0.9 and thickness 2.1mm,the best reflection loss RL=-40.1d B,and the maximum frequency band width of RL<-10d B,covering10.37-18ghz.x=0.9,1.5 mm to 4.5 mm in thickness range,RL<-10 d B of the absorption band completely covered 9.6 GHz-18 GHz frequency range.Therefore,SrFe_10.2Sn_0.9Zn_0.9O₁₉sample has the best performance on electromagnetic wave loss.Compared with Sn-Ni doped strontium ferrite,the microwave absorption performance of Sn-Zn doped strontium ferrite is significantly improved,the effective absorption thickness decreases,and the effective absorption bandwidth increases.In conclusion,SrFe_10.2Sn_0.9Zn_0.9O₁₉is superior to other M-type ferrites and most advanced materials.La₂CoFeO₆,La₂CoCuO₆,La₂CoMnO₆and La₂CoNiO₆were prepared by sol-gel reaction method.It can be seen from the XRD diagram that the crystal structure is,and the generated samples are single-phase.The tolerance factor of the samples was calculated according to the atomic radius,and the samples were of double perovskite structure.UV-Vis measurement of the sample shows that the band gap is the smallest when La₂CoMO₆is doped with Mn,which is 1.16 e V.Therefore,the addition of Mn will introduce more impurity levels and improve the optical properties of the sample.In terms of microwave absorption RL curve,the best reflection loss RL=-34.68d B occurs when the sample thickness is D=9.9mm and the frequency is 9.07GHz when La₂CoMO₆is doped with Mn.In the thickness range of 2.7mm-4.5mm,the absorption band with RL<-5d B completely covers the frequency range of5.8GHz-15GHz.Therefore,Mn doped double perovskite can improve microwave absorption performance.