Study On Electromagnetic Properties Of Nicuzn-ferrite Ceramic By Cold Sintering Method

The fast development of information technology and the arrival of 5G era pose more severe challenges to the research of electronic devices,which require electronic devices to be more miniaturized,high-frequency,integrated and multi-functional.Ni Cu Zn-based magnetic dielectric functional composites have attracted great attention due to their dielectric properties and high magnetic permeability.However,the traditional high-temperature solid-state sintering method usually needs to be sintered at a very high temperature,which not only easily generates hybrid phases,weakens the performance of the material,but also consumes a lot of energy due to high-temperature.In addition,the excessively high sintering temperature makes it difficult to co-fire these materials with silver electrodes.This work chooses the Ni Cu Zn-based magnetic dielectric complex ceramics as the research object,using cold sintering method,starting from the design and selection of ceramic powders,the design and adjustment of microstructure,and the optimization of experimental process parameters to prepare magnetic dielectric multiphase ceramics with high/close permeability and permittivity.On this basis,combined with the HFSS,the materials used in the microstrip antenna dielectric substrate were simulated and analyzed.The whole research contents are as following:?1?Preparation of ceramic powders Li₂MoO₄?LMO?,Na₂WO₄?NWO?and Ni_0.2Cu_0.2Zn_0.6Fe_1.94O₄?NCZO?: Using traditional high-temperature solid-state synthesis method,the phase formation conditions of three precursor phases were determined,namely: the formation of the phase condition of LMO is 540?/4h,the NWO phase formation condition is 500?/4h,and the NCZO phase formation condition is 900?/2h.The XRD analysis shows that all ceramic powders are singlephase,without second phase,which provides the required precursor materials for the cold sintering of the complex ceramics.?2?Study on properties of magnetic dielectric multiphase ceramics?1-x?LMO-x NCZO: A series of LMO/NCZO magnetic dielectric complex ceramics with deionized water as sintering additive have been prepared by cold sintering method at 150? for 30 min under a pressure of 200 MPa.Traditional Ni Cu Zn-based composite ceramics have a high preparation temperature?1150? ? 1250??.In this paper,relatively high density?>95%?can be achieved by cold sintering method under ultra-low temperature of 150? and applied pressure.And,it has very good performance with low loss,high dielectric constant and permeability.Component 0.46LMO-0.54 NCZO composite material: dielectric constant is 8.2?100 MHz?,dielectric loss is 0.0076?100 MHz?;permeability is 6.4?100 MHz?,magnetic loss is 0.220?100 MHz?.The theoretical calculation values of the composite materials with different compositions are in good agreement with the experimental results,and are expected to be utilized in the dielectric substrate of miniaturized antennas.?3?Study on properties of magnetic dielectric multiphase ceramics?1-x?NWO-x NCZO: A series of?1-x?NWO-x NCZO composite material was prepared by cold sintering method under the condition of temperature as low as 150?.The results show that the density and sintering ability decreased with the increase of the ferrite content,but the ceramics still show good electromagnetic properties.The component 0.4NWO-0.6NCZO composite material has higher dielectric constant and permeability,and these two are almost equal,which can effectively solve the impedance matching problem between the antenna and free space.The dielectric constant is 7.7?100 MHz?,the permeability is 7.6?100 MHz?,the dielectric loss is 0.027?100 MHz?,and the magnetic loss is 0.25?100 MHz?.?4?The three-dimensional electromagnetic simulation software HFSS simulates and analyzes the materials used in the microstrip antenna dielectric substrate: The different components of NWO/NCZO composite material as the microstrip antenna dielectric substrate material have been simulated and analyzed by HFSS.The results show that when a magnetic dielectric material is used for the dielectric substrate of the microstrip antenna,the size of the dielectric substrate can be effectively reduced,and the introduction of the magnetic phase can expand the bandwidth on the basis of little impact on the returned loss.