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Dielectric Properties And Regulation Of Elements Dopping In Co2Y-type Hexaferrites

Posted on:2022-01-15Degree:MasterType:Thesis
Country:ChinaCandidate:P J WangFull Text:PDF
GTID:2480306572480474Subject:Condensed matter physics
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With the rapid development of science and technology,social production and people's life has been inseparable from electronic products,because electronic devices tend to be integrated and intelligent.Nowadays,the preparation of high-performance dielectric materials has become the key to solve the miniaturization of electronic devices.As a functional material,Y-type hexaferrites have been widely studied,because of the excellent magnetoelectric properties,as well as the potential of being a kind of new information carrier.How to enhance and regulate the dielectric properties of Y-type hexaferrites have attracted much attention.In this dissertation,Co2Y-type hexaferrites are used as the matrix to enhance and regulate its dielectric properties through element doping at different positions,and the physical mechanism of its high temperature dielectric is studied.The main contents are as follows:(1)Ba2-xSrxCo2Fe12O22(0?x?0.5)series ceramic samples were prepared by traditional solid phase method,and the structure,microstructure and dielectric properties of the ceramic samples were systematically studied.The results of X-ray diffraction pattern and scanning electron microscopy showed that the lattice parameters decreased monotonously with the increase of the doping amount of Sr at Ba site,and the average grain size presented a complex trend.Dielectric constant measurement results show that in300-650 K of wide temperature zone and 1 k Hz to 1 MHz wide frequency range.the dielectric constant of all samples(??)are greater than 103 and that is a giant dielectric effect.However,with the increase of Sr doping content,the variation of the dielectric constant with respect to the amount of Sr doping is completely different trend at room temperature(300 K)and high temperature(600 K).Through the analysis of dielectric response,complex impedance and electrical conductivity,it is shown that the variation of dielectric constant with relation to the doping amount of Sr at 300 K is mainly determined by relaxation activation energy.The variation of dielectric constant at 600 K is mainly related to the average grain size.(2)Ba2Co2-xMgxFe12O22(0?x?1)series ceramic samples were prepared by the traditional solid-state reaction method.The effects of Mg doping on the dielectric response and relaxation behavior of Ba2Co2-xMgxFe12O22(0?x?1)samples have been experimentally investigated.The experimental results show that the addition of Mg at Co site can achieve large dielectric response(??>103).Mg doping can cause three obvious effects,that is,the number of Co3+ions in the sample is decreased,and then the number of Fe ions is increased in the oxygen octahedron,the relaxation activation energy is improved,and the resistance and capacitance at the grain boundary of the sample are increased.With the increase of the doping content of Mg,the dielectric relaxation gradually changes from the grain dominant to the grain boundary dominant,which may be due to the increase of grain boundary resistance and capacitance caused by doping.
Keywords/Search Tags:dielectric constant, dielectric relaxation, giant dielectric response, hexagonal ferrite
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