Study On Bi₂O₃-Fe₂O₃-Pr₂O₃ Phase Relationship And Its Compound Structure And Properties

With the advent of the digital information age,electromagnetic pollution（EM）has become a concern while enriching people’s lives.To reduce electromagnetic pollution,it is urgent to study the materials that can absorb electromagnetic waves to prevent electromagnetic pollution.As an information diagram of phase equilibrium of the material system,phase diagram has become an important means of scientific research and tract problem-solvingving.Determine the phase equilibrium relationship has certain significance to explore and promote the search for new absorbing materials.In this experiment,the phase equilibrium relationship of the Bi₂O₃-Fe₂O₃-Pr₂O₃system at 1073 K was established by the solid-phase method.On this basis,the sample was synthesized by the sol-gel method,and the effect of a-site element doping on the structure and properties of BiFeO₃was investigatedXRD analysis shows that the Bi₂O₃-Fe₂O₃-Pr₂O₃system at 1073 K has 9 single-phase regions,6 two-phase regions,and 7 three-phase regions,and no quaternary compounds are found under this condition.When Pr³⁺≤0.1,the Pr element is successfully solidly dissolved into the lattice of BiFeO₃,and the R3c-BiFeO₃structure is still rhomboidal.When the content of the Pr element increases gradually,the distortion of BFO is obvious,and it changes to the Pbnm type with an orthogonal structure.It is found that Bi element can be well solubilized into the lattice of Pr FeO₃,and the maximum solubilization of Bi₂O₃in Pr_1-xBi_xFeO₃reaches 57.5 at.%.There is two solid solution phase in the Bi₂O₃-Pr₂O₃binary system.One is Bi_0.775Pr_0.225O_1.5-type with its（Bi₂O₃）_1-x（Pr₂O₃）_xsolid solubility range x is（0.1842≤x≤0.3462）,the other is Pr₆O₁₁-type which the range of solid solution（Pr₂O₃）_1-y（Bi₂O₃）_y,is 0≤y≤0.1.Perovskite Bi_1-xPr_xFeO₃（x=0.0,0.05,0.1,0.15）was prepared by sol-gel self-propagating combustion assisted by organic tartaric acid.The influence of Pr on dielectric properties and permeability was further studied.When 15%Pr is introduced,the lowest reflection absorption loss can reach-32.34 d B,but the absorption bandwidth is only2.25 GHz.However,the minimum reflection loss of the Bi_0.95P_0.05FeO₃sample is-27.31d B,and the effective bandwidth can reach 3.41 GHz.The properties of BPFO perovskite were discussed by analyzing the structural changes in the process of substituting Pr for Bi.The effects of strong interaction force,residual magnetization,and natural resonance on the absorption properties of nano-ceramics were discussed.It provides a reliable candidate material for preparing excellent electromagnetic attenuation ceramic materials.Heavy rare earth non-magnetic Y ion was used to replace Bi ion.With the increase of rare earth Y³⁺content,the structure of the nanoparticles changed from rhomboid phase（R3c）to orthotropic phase（Pbnm）at x=0.15.The size of Bi_1-xY_xFeO₃nanocrystals can be well regulated by Y substitution.The results show that Y substitution reduces the volatilization of Bi element,thus effectively reducing the content of oxygen vacancy and Fe²⁺ions,and effectively improving the magnetic properties.The results show that a certain amount of rare earth Y substitution can significantly promote the electromagnetic wave absorption characteristics of Bi_1-xY_xFeO₃（x=0.0,0.05,0.10,0.15）nanoparticles.The results show that when x=0.1,the RL of the sample is 3.29 GHz when the simulated thickness is 2.2 mm and less than-10 d B Bi_0.9Y_0.1FeO₃nanoparticles have excellent microwave absorption（MA）performance,which is mainly attributed to their multi-polarization,good impedance matching,interface reflection,and magnetic loss.Therefore,Bi_0.9Y_0.1FeO₃nanoparticles can be used as a kind of lightweight and high-performance absorbing nanomaterial.The structure of Bi_1-xCa_xFeO₃perovskite was analyzed by the sol-gel self-propagating combustion method.The effects of structural changes,remanent magnetization,and natural resonance on the absorbing properties of nano-ceramics during the substitution of Ca²⁺for Bi³⁺were discussed.Thus,thin and efficient microwave absorbing materials with effective absorption bandwidth were obtained.The small size of alkaline earth metal Ca²⁺ion（0.99A）can successfully enter the crystal structure and induce the BCFO structure transformation by replacing the large radius of the Bi³⁺ion.When the doping amount reaches 0.15,BCFO changes from the rhomboid R3c phase to Pm-3m phase.SEM results show that the grain size of Bi_1-xCa_xFeO₃decreases.Generally,grain size decreases,and the specific surface area will increase.The main reason for specific surface area growth is particle agglomeration caused by high activity on the surface of nanoparticles,which is consistent with SEM performance.Pore penetration and specific surface area increase,which has a positive effect on the improvement of magnetic properties and absorbing properties.The doping of the Ca element destroys the spin helix modulation structure,and the change of Fe-O-Fe bond angle results in a certain degree of change in octahedral position,thus enhancing the magnetic properties of BCFO.When the simulated thickness is 2 mm,Bi_0.9Ca_0.1FeO₃has a good broadband effect at 10.23 GHz.When the minimum reflection loss is-36.91 d B,the effective bandwidth is up to 2.81 GHz...