Investigation On The Co₂Z Hexalgonal Ferrites Materials With Modifying Elements

For Co₂Z hexaferrite has excellent soft magnetic characteristics such as high initial permeability,high cut-off frequency,low tagent and high themalstablity,it is a soft magnetic ferrite has the potential applications in the fields of anti-electromagnetic interference(EMI).In order to meet the requirements of anti-electromagnetic interferenc materials in different communication fields,the microwave electromagnetic performance of Co₂Z should be improved.Therefore, investigation of Co₂Z doped with oxides has been developed fast.Co₂Z hexaferrite materials were prepared by conventional ceramic technique.In order to improve the microwave electromagnetic performance of Co₂Z,we invesitigated the preparation technology and droping with different ions.The investigation focused on the mechanism that the initial permeability of Co₂Z hexaferrite materials could improve without the losing of cut-off frequency by dopring with strontium ion and comparing the influence of different rare earth ions. The microscopic structure characteristic and phase distribution of the composites were investigated by means of SEM and XRD,and the magnetic performance of the samples were tested.The measurement results showed that,when the Co₂Z hexaferrite materials was doped by strontium,the magnetic anisotropy field was effected,so the cut-off frequency was moved to higher frequency field.At the same time the Z-type phase distribution,microscopic structure characteristic were improved,therefore the initial permeability was also increased.In this group of samples,the sample with x=0.4 had the best magnetic performance,initial permeability increased to 14,and the cut-off frequency increased to 2.45GHz.The doping of rare earth ions could accelerate the growth of Co₂Z hexaferrite's grains with limits,so the initial permeability and the density of samples were increased.In the process,the rare earth ions substituted the ferrous ion at octahedral position,the rare earth ions with different magnetic moment could control the change of initial permeability.Comparing the three groups of sample doped with rare earth irons,the doping of Sm³⁺ ion could get the best magnetic performance,when x=0.025,initial permeability was 16,and the cut-off frequency was 2.021GHz.