Study On The Synthesis And Properties Of The Laminated Ba(Fe_0.5Nb_0.5)O₃/Ferrite Magnetodielectric Composites

In recent years,the great changes have happened in the electronic industry.The miniaturization,micromation and environment-friendly materials are dramatically increasing in the electronic industry.So the multifunctional materials are greatly urged by the electronic and information devices.A growing number of scholars have taken the attention to the multifunctional materials.And the requirements on the miniaturization of ferroelectric materials and ferromagnetic materials are dramatically increasing due to the fact that they are widely used in electronic information industry.The properties of multifunctional materials can not be obtained by pure ferroelectric or ferromagnetic materials.Single-phase magneto-dielectric materials not only have dielectric properties but also magnetic properties,however,the Curie temperature of single-phase magneto-dielectric materials is much lower than the room temperature.The magneto-electric effect can not be got on condition of room temperature.Meanwhile,the conditions of preparing materials and the price is not are allowed to the application.So the magneto-dielectric composites have stimulated much scientific and technological interest due to the multifunctional properties.Magneto-dielectric composite materials are composed of ferroelectric and ferromagnetic materials.Compared with single-phase magneto-dielectric materials,magneto-dielectric composite materials have higher Curie temperature.According to the structure of composites,the composite materials can be classified into 0-3 type composite,2-2 type composite and 1-3 type composite.The 2-2 type composite is also called laminated composites.According to the different structure of the composites,the magneto-dielectric properties can be improved greatly.In this paper,the lead free magneto-dielectric laminated composites were prepared under the condition of high temperature.In this paper,two methods were adopted to prepare the laminated composites which called solid-state sintering method and tape casting method.Ba(Fe_0.5Nb_0.5)O₃/Bi_0.2Y_2.8Fe₅O₁₂?BFN/BYIG?laminated composites and Ba(Fe_0.5Nb_0.5)O₃/Ni0.8Zn0.2Fe2O4?BFN/NZFO?laminated composites are prepared by this two methods.The mechanism and process of the solid-state sintering method and tape casting method have carried on the detailed introduction.And the results have been measured by the test equipment.Discussion on the experiment result,through a variety of testing methods of layered magneto-dielectric composite materials to analyze the results.X-ray diffractometer?XRD?and scanning electron microscopes?SEM?is used to test the phase composition of raw materials and microstructure of the composite.The dielectric properties and the impedance of the composites were measured using an impedance analyzer.The magnetic hysteresis loops of the composites were performed by a vibrating sample magnetometer.Frequency dependence on the magnetic properties of the composites was measured using an impedance analyzer.?1?The BFN/BYIG laminated composites were prepared by the solid-state sintering method.The microstructure of the composites indicates that BFN and BYIG phases can coexist in the composites.Excellent dielectric properties from 100 Hz to 1 MHz can be obtained.The permeability of the laminated composite is quite high.?2?The BFN/BYIG laminated composites were prepared by the tape casting method.The microstructure of the composites indicates that BFN and BYIG phases can coexist in the composites and the structure is compact.There has not pore on the surface of the laminated composite.Excellent dielectric properties obtained.Compared to the composites which were prepared by the solid-state sintering method,the laminated composites are more compact and very few pores can be observed.And the dielectric properties are more excellent,the dielectric constant is much higher and the dielectric loss is much lower than 0-3 type composites.The main polarization of the BFN/BYIG laminated composite is interfacial polarization at the interface of the two phases.?3?The BFN/NZFO laminated composites were prepared by the solid-state sintering method.The microstructure of the composites indicates that BFN and BYIG phases can coexist in the composites and the structure is compact.Compared with the magneto-dielectric particulate composites,the laminated composites possess higher the dielectric constant and lower loss.And the Ms of the BFN/NZFO increases with the increasing NZFO content.The increase in the values is due to the magnetic phase NZFO.?4?The BFN/NZFO laminated composites were prepared by the tape casting method.Under the temperature of 1300 oC,the microstructure of the composites indicates that the composite is very compact.Meanwhile,BFN and NZFO phases can coexist in the composites.There has not pore on the surface of the laminated composite.The dielectric the dielectric constant is much higher and the dielectric loss is much lower.And the properties are much excellent than the 0-3 type composites which prepared by tape casting method.