The Electromagnetic And Microwave Absorption Properties Of Barium Ferrite-based Composites

Ferrite bismuth?BFO?and barium ferrite(BaFe₁₂O₁₉),due to their excellent dielectric and magnetic performance respectively,have great prospective applications prospective in fields such as data storage,sensors,spin electronics,hard magnetic and soft magnetic materials.In recent years,researchers are developing BFO into microwave absorption material due to its good dielectric properties.However the weak magnetism limits its further application.As a classic microwave absorption material,BaFe₁₂O₁₉ possesses a high natural resonance frequency beyond X band.To tune its natural resonance frequency to realize the improvement of x-band magnetic loss is a problem worth studying.Furthermore,a single material is very difficult to possess large electric loss and magnetic loss at the same time,so the composite of BFO/BaFe₁₂O₁₉ is put forward based on their respective excellent dielectric and magnetic properties as well as the possible achievement of electromagnetic matching.At first,we prepared BFO by the sol-gel method and molten-salt method,we try to study the changes of microstructure caused by preparation methods on the performance of electromagnetic and microwave absorption.BFO prepared by sol-gel method has better dielectric properties and microwave absorption performance with a minimum reflection loss of-20 dB.We consider the main difference between the two samples is ion size,a difference between with nanoscale and micron scale.The smaller the particle size is,the greater the paragraphs polarization and conductance are,based on the debye equation.On the other hand due to the small particle size,multiple reflections may happen.BFO prepared by sol-gel method has better microwave absorbing properties.Secondly,Mn,Ti ions were used to substitute BaFe₁₂O₁₉ to modification the magnetic loss.Replacement of Mn,Ti contributes to magnetic exchange interactions decline,and the natural resonant frequency shifting towards lower frequency.At x=5sample we found a perfect natural resonance peak,and the magnetic loss reaches up to 0.8,with a reflection loss of-17 dB,which means the tuning of electromagnetic is achieved.At last,we prepared a series of BFO-BaFe₁₂O₁₉ composites with different volume ratios.When the volume ratio is 3:1,the minimum reflection loss is-40 dB,which almost 2-3 times of that of BFO or BaFe₁₂O₁₉.High intensity absorption is achieved.However,the electromagnetic parameters are not the best among different volume ratios,this is due to the electromagnetic mismatch,the reflection of electromagnetic wave is less.The result verifies the idea that composite with dielectric and magnetic materials leads to a combination of dielectric and magnetic properties and achieves electromagnetic matching,finally enhances the microwave absorption.The composite of BFO/BaFe₁₂O₁₉not only develops a new efficient microwave absorbing material,more importantly provides a way of designing microwave absorbing materials.