Study On The Preparation And Performance Control Of Cobalt-Ferrix-based Magneto-electric Coupled Structural Ceramics

With the rapid development of electronic information technology and mobile communication,the miniaturization and multi-function of electronic equipment components have become the inevitable trend of the development of modern science and technology.As a kind of multiferroic functional materials with both ferroelectric and ferromagnetic properties,magnetoelectric composites provide a possibility of polarization controlled by magnetic field or magnetization controlled by electric field,which has become a hot spot in materials science research.The purpose of this paper is to explore the preparation process,composition and microstructure of（1-x）Ba(Ti_1-ySn_y)O₃-x(Ba_1-zCa_z)Ti O₃-Co Fe₂O₄（BCST-CFO）multiphase iron material.The main research contents are as follows:（1）Rare earth ion Lu³⁺doped Ni_0.5Zn_0.5Lu_xFe_2-xO₄（x=0.000,0.004,0.008,0.012,0.016 and 0.020）ferrite was prepared by solid phase sintering method,and the effects of different contents of Lu³⁺on the matrix structure and properties were studied.The results show that the samples of all components are cubic spinel structure and no impurity phase is formed.With the increase of doping amount of Lu³⁺,the lattice constant of the sample increases monotonically.The electron energy spectrum shows that the theoretical proportion of each element in the sample is basically consistent with the actual proportion.The dielectric constant gradually decreases with the increase of the applied electric field frequency and tends to a stable value at high frequency.With the increase of Lu³⁺concentration in the sample,the saturation magnetization of the sample first increased and then decreased,and reached the maximum value at x=0.004,M_smax=71.41emu/g.（2）A series of（1-x）Ba(Ti_1-ySn_y)O₃-x(Ba_1-zCa_z)Ti O₃（x=0.2、0.1,y=0.12、0.1,z=0.3、0.4）composite perovskite ceramics with different ratios were prepared by solid-phase sintering method.The effects of different raw material combinations on the structure and properties of composite perovskite were studied.The results show that all the samples are of perovskite structure and no impurity phase is formed.With the increase of frequency,the dielectric constant decreases monotonically and tends to a stable value at high frequencies.With the increase of temperature,the dielectric constant first increases and then decreases,and the Curie temperature peak appears in the vicinity of100-110℃.All the samples showed obvious ferroelectric hysteresis loops,and the saturation magnetization of the second group was the highest(M_smax=25.2μC/cm²).There is an obvious correlation between the piezoelectric properties of the materials and the polarization strength,and the piezoelectric coefficients of the two groups of samples are the highest,d_33max=366p C/N.（3）A series of BCST-CFO composite ceramics with different proportions（BCST:CFO=0∶10,1∶9,3∶7,5∶5,7∶3,9∶1,10∶0）were prepared by solid phase sintering.The effects of the relative contents of the two groups of materials on the structure and magnetic and electrical properties of the composite ceramics were investigated.The results show that with the increase of ferroelectric phase BCST in the composite,the CFO characteristic peak of the spinel structure of the sample decreases gradually,and the characteristic peak of ferroelectric phase BCST increases gradually.With the increase of the frequency of the applied electric field,the dielectric constant decreases monotonically and tends to a stable value at high frequencies.When BCST is the main component of the sample,its dielectric constant appears an obvious Curie temperature peak near 100℃.The ferroelectric property test results show that there is obvious ferroelectric hysteresis loop when BCST is the main component of the sample.The results of ferromagnetic tests show that the saturation magnetization of the sample decreases monotonously with the increase of ferroelectric phase content.When the sample is pure perovskite structure BCST,the saturation magnetization of the sample is almost zero.The piezoelectric coefficient increases monotonically with the content of ferroelectric phase BCST in the sample increasing.When the sample is pure phase BCST,the piezoelectric coefficient reaches the maximum value,d_33max=370pC/N.