Study On Y₂O₃-BaO-Fe₂O₃ Phase Relationship And Its Compound Absorbing Properties

Electromagnetic radiation brought by 5G technology and various electronic devices seriously endangers biological health,and absorbing materials provide a feasible method to solve this problem.High-quality absorbing materials depend on their microscopic morphology,crystal structure,calcination temperature and magnetic properties.material properties.In this project,the solid-phase method was used,and the isothermal cross-section of the Y₂O₃-BaO-Fe₂O₃system at 1473 K was measured by XRD,and the phase relationship between the oxides was studied,so as to provide a reasonable production process and ratio for the compound.Taking the phase diagram as the experimental guide,the sol-gel self-combustion method was used to prepare the YFeO₃ferrite microwave absorbing materials substituted by the alkaline earth metals Ba,Sr and Ca at the A site.The microscopic morphology,crystal structure and element valence were elaborated The relationship between state change and magnetic and absorbing properties.The specific research results are as follows:（1）The phase relationship of the isothermal cross section of the Y₂O₃-BaO-Fe₂O₃system at 1473 K was experimentally determined,and there were 11 single-phase regions,20 two-phase regions,and 11 three-phase regions.When Y₂O₃:Fe₂O₃:BaO=0.5:0.333:0.167,the quaternary phase YBa₃Fe₂O_7.5+δis formed;the measurement results show that YFeO₃and Ba FeO_3+δcan be partially dissolved,and the solid solubility is 3.2at%;the quaternary phase and Ba FeO_3+δalso has a partial solid solution,and the solid solubility is 1.5 at%,that is,Y³⁺has a solid solution phenomenon in Ba FeO_3+δ.（2）Alkaline earth metals have good electrical and thermal conductivity,and rare earth ferrite has excellent magnetic,optical and dielectric properties.Therefore,the sol-gel self-propagation method was used to prepare YFeO₃materials with alkaline earth metal Ba²⁺instead of Y³⁺.Due to the small solid solubility of Ba²⁺in yttrium ferrite,Ba FeO_3+δis generated.With the increase of Ba content,the magnetic behavior of the sample gradually changes from weak magnetic and antiferromagnetic to antiferromagnetic.Due to the damaged structure,the second phase exists,resulting in poor wave absorption performance of the sample.（3）The Y_1-xSr_xFeO₃（x=0,0.05,0.1,0.15）perovskite ferrite absorbing material was studied,and the tested XRD patterns were refined using XRD technology and Full Prof software,which confirmed the orthogonal perovskite Formation of the structure（SG:Pnma）.SEM and TEM results show that the average particle size distribution of the samples is between 110-160 nm.The particle size increases with the increase of Sr²⁺concentration,which is related to the preferred orientation of grain growth and partial substitution of ions.The analysis of element valence states shows that Fe³⁺is always accompanied by Fe²⁺in perovskite,and oxygen vacancies increase obviously after Sr²⁺ion doping,and the sample gradually changes from weak ferromagnetic state to paramagnetic state.At 12.2 GHz,the minimum reflection loss（R_L）of the Y_0.95Sr_0.05FeO₃sample reaches-30.87 d B,where the effective absorption bandwidth（EAB,R_L≤-10 d B）reaches 2.4GHz（11.3-13.7 GHz）.The EAB of the Y_0.85Sr_0.15FeO₃sample reaches 2.64 GHz,corresponding to a frequency range of 9.0-11.6 GHz（X-band）.（4）The diffraction peak of the Y_1-xCa_xFeO₃sample corresponds to the orthorhombic perovskite YFeO₃,and the substitution of Ca²⁺successfully forms a solid solution in the sample.With the increase of Ca doping content,the grain size of the samples gradually decreased,and the oxygen vacancies increased significantly.With the increase of Ca concentration,the magnetic and microwave absorption properties of the samples are effectively improved.When the simulated thickness is 2.0 mm,the reflection loss R_Lof the Y_0.9Ca_0.1FeO₃sample at 11.9 GHz reaches-28.63 d B（99.99%）,and the EAB reaches 4.64GHz,covering Ku-band,with good broadband effect.