Effect Of Ru Doping On Microwave Absorption Of SrFe₁₂O₁₉ And Magnetic Properties Of MnCo₂O₄

Microwave absorbing materials with a working frequency of 1-18 GHz are widely used in commercial,industrial and defense industries.Currently,the electronics industry has rapidly developed into this frequency range.Microwave absorbing materials can convert electromagnetic waves into thermal energy by using dielectric loss or magnetic loss.Among them,BaFe₁₂O₁₉9 and SrFe₁₂O₁₉ are considered to be important permanent magnet materials with high magnetization,high stability,low cost and easy manufacturing.BaFe₁₂O₁₉9 and SrFe₁₂O₁₉ with high coercive field have a resonance frequency1)1)higher than 40 GHz.In the 18 GHz range,there is no microwave absorbing property,so in order to improve its microwave absorption characteristics,it is necessary to reduce the resonance frequency of the microwave absorbing material because1)1)is related to the anisotropy fieldand has 21)1)=for the c-axis anisotropy.As the easy magnetization direction?EMD?changes from the c-axis to the ab plane,the anisotropy field is greatly reduced.Changing the EMD direction is a solution.Some researchers domine Co and Ir ions in BaCo_xIr_xFe_12-xO₁₉.When x=0.4,they have a minimum frequency of 2 GHz,since Ir ions are 5d noble metals,and Ru ions are 4d precious metals.Therefore,it is expected that Ru ions should play a similar role.Therefore,we doped Ru ions in SrFe₁₂O₁₉ to improve the microwave absorption characteristics in the frequency range of 1-18 GHz.We did some experiments on the doping of SrFe₁₂O₁₉ and analyzed the experimental results.we also studied various magnetic transitions of MnCo₂O₄ under Ru doping.The electron exchange between different ions in MnCo₂O₄ is the basis of magnetic exchange interaction.Ferrous magnetism has been observed in MnCo₂O₄.It is meaningful to study the magnetic and electrical properties of Mn_1-xRu_xCo₂O₄ by using Ru⁴⁺,which is one more than Mn³⁺,based on the same d-orbital electron Ru⁴⁺doping.Ru is substituted for Mn to make RuCo₂O₄ an antiferromagnetic spin glass.Considering that the magnetic exchange interaction in Mn_1-xRu_xCo₂O₄ is closely related to the electron transfer between different ions,the doping ions may have a great influence on its magnetic properties.Therefore,we also did a series of experiments on Mn_1-xRu_xCo₂O₄ to clarify its magnetic properties.The results show that Mn_1-xRu_xCo₂O₄has a ferrimagnetic transition at 164 K.It occurs at 164 K for x=0,0.05 and 0.1,and decreases to 158 K for x=0.3 and 117 K for x=0.5.There is an antiferromagnetic transition at 102 K,which is 102 K for x?0.3 and 99 K for x=0.5.The coexistence and inertia effect of the doping amount x on the transition temperature in Mn_1-xRu_xCo₂O₄indicates that the magnetic phases are separate and dominated by the FIM phase.At x=0.5,Mn_0.5Ru_0.5Co₂O₄ AFM is the main phase,and there is also a characteristic of the FIM phase.