Study On Nd₂O₃-Fe₂O₃-Bi₂O₃ Phase Relationship And Its Compound Structure And Properties

In this paper,the ternary system of Nd₂O₃-Fe₂O₃-Bi₂O₃ and related compounds are used as the research object.The ternary system experimental samples at 700°C are synthesized by solid-phase method to determine the phase equilibrium relationship and crystal structure.Bi Fe O₃ nano powder samples were prepared by the sol-gel method,and the effects of rare earth Sm,Nd and Mn doping on the crystal structure,micromorphology,element valence,magnetic properties,and absorbing properties of Bi Fe O₃ were studied.The phase equilibrium relationship of the Nd₂O₃-Fe₂O₃-Bi₂O₃ ternary system at700°C was experimentally determined by X-ray diffraction method.The experiment found that the Nd₂O₃-Fe₂O₃-Bi₂O₃ ternary system at 700°C has 10 single-phase regions,18two-phase regions and 9 three-phase regions.No new ternary compounds were found.The rare earth Nd can be well dissolved into the lattice of the Bi Fe O₃ compound,and it has been found that the crystal structure of Bi Fe O₃ will change with the increase of the doping amount of Nd.When the content of Nd is x?0.1,it belongs to the rhombohedral structure with the R3c space group;when the content of Nd is 0.15?x?0.2,it changes from rhombohedral structure to cubic structure with the Pm???m space group;When the content of Nd is 0.25?x?1,the compound Bi_1-xNd_xFe O₃ has an orthogonal structure with the Pbnm space group.There is the Bi_0.775Nd_0.225O_1.5-type solid solution phase in the Nd₂O₃-Bi₂O₃ binary system,which belongs to the R-3m crystal structure.The solid solubility range x of Bi_1-xNd_xO_1.5 is 0.224?x?0.276.The Bi_1-xNd_xFe O₃?x=0.0,0.05,0.1,0.15?samples were prepared by the sol-gel method.The X-ray diffraction analysis results show that when the content of Nd is x?0.1,the sample has a rhombohedral structure with the R3c space group.When the content of Sm is x=0.15,its spatial structure is transformed into a cubic structure with the Pm???m space group;the doping of rare earth Nd element can effectively inhibit the growth of Bi_1-xNd_xFe O₃ grains,and at the same time can reduce the formation of Fe²⁺ions and oxygen vacancies or defects in the compound.The substitution of rare earth Nd elements for Bi can significantly improve the magnetic and absorbing properties of Bi Fe O₃.When the content of Nd is x=0.1,the Minimum reflection loss value is-33.1d B at 10.7 GHz,and its effective bandwidth?R<-10 d B?actually reaches about 3.2 GHz,which has a relatively excellent bandwidth effect.The Bi_1-xSm_xFe O₃?x=0.0,0.05,0.1,0.15?powers were prepared by the sol-gel method.The X-ray diffraction analysis results show that when the content of Sm is x?0.1,the sample has a rhombohedral structure with the R3c space group.When the content of Sm is x=0.15,its spatial structure is transformed into a cubic structure with the Pm???m space group;the doping of rare earth Sm can effectively inhibit the growth of Bi_1-xSm_xFe O₃ grains,and at the same time can reduce the formation of Fe²⁺ions and oxygen vacancies or defects in the compound.The rare earth Sm doping can significantly improve the magnetic and microwave absorption properties of BFe O₃.When the content of Sm is x=0.1,the best microwave absorption performance is-32.9 d B at a frequency of 11.7GHz.It reaches about 2.6 GHz,which has a relatively good bandwidth effect.Bi Fe_1-xMn_xO₃?x=0.0,0.05,0.1,0.15?samples were successfully prepared by the sol-gel method.The results of X-ray diffraction analysis showed that when the content of Mn is x?0.05,the samples had a rhombohedral structure with R3c space group.When the doping amount of the Mn element exceeds 0.05,the compound changes from a rhombic structure to a cubic structure corresponds to the Pm???m space group.The doping of Mn element can effectively suppress the growth of crystal grains,and at the same time reduce the content of Fe²⁺ions and oxygen vacancies or defects.When the Mn addition amount is0.05,the magnetic properties and wave absorbing properties of Bi Fe_0.95Mn_0.05O₃ are the best.Doping with proper amount of Mn enhances the microwave absorption performance of Bi Fe O₃.When the content of Mn is x=0.05,it has the best microwave absorption performance of-29.5 d B at 11.6 GHz,and its effective bandwidth?RL<-10 d B?is 0.7 GHz.