| In recent years, BaO-TiO2microwave ceramics has attracted the interest ofthe majority of research workers due to their excellent microwave dielectricproperties. However, the high sintering temperature and the difficulty ofobtaining stable phase have been the bottleneck its development. In this paper,we tried to dope with different content of ZnO/Nd2O5to BaO-TiO2microwaveceramics to reduce the sintering temperature and improve the dielectricproperties. Based on above researches, the dielectric-magnetic compositeceramics have been investigated in the microwave. The microstructure, dielectricand magnetic properties of the ceramics were characterized by X-ray diffraction,scanning electron microscopy, energy dispersive spectroscopy, vibratingspecimen magnetometer and network analyzer.Microwave ceramics based on BaO-R2O3-TiO2（R2O3=0, Sm2O3, Nd2O3）doped with ZnO/Nb2O5were prepared by conventional ceramic technique. Theresults show that the sintering temperature of microwave ceramics was reducedwith doped additive. Especially, the5wt%ZnO/Nb2O5doped microwaveceramics exhibited optimum dielectric properties. The results showed that:（1） BaO-TiO2ceramic with5wt%ZnO/Nb2O5sintered at1240oC for4hexhibited a uniform and compact microstructure, and consisted of BaTi4O9andBa2Ti9O20. And its dielectric properties are followed as: εr=37.4, tanδ＜10-4andαε=-6.9×10-7/oC, αε=-5.4×10-6/oC.（2） A single phase of BaSm2Ti4O12was found in the BaO-Sm2O3-TiO2ceramic with5wt%ZnO/Nb2O5sintered at1240oC for4h. And the sample had auniform and compact microstructure accompanied with εr=79.5andtanδ=4.6×10-4,αε=-4.8×10-6/oC.（3） BaO-Nd2O3-TiO2ceramic with5wt%ZnO/Nb2O5sintered at1260oC for4h exhibited a uniform and compact microstructure, was a single phase ofBaNd2Ti5O14with εr=89.5and tanδ=8.2×10-4.In this paper, BaFe12O19as magnetic materials, Ba2Ti9O20as dielectricmaterial, through the preparation magnetoelectricity composite ceramic, and study the microscopic structure, dielectric and magnetic properties. The resultsshowed that:（1）0-3type Ba2Ti9O20-BaFe12O19composite ceramics had been fabricatedsuccessfully by conventional ceramic processing. The sintering temperature hadno significant effects on the phase structure of the ceramics. The investigationsindicated that the initial Ba2Ti9O20/BaFe12O19ratio has a great effect on thedielectric of the ceramics. In addition, the dielectric constant does not changelargely with increasing BaFe12O19content, whereas the dielectric loss increased.95%Ba2Ti9O20+5%BaFe12O19composite ceramics has optimum dielectricproperties sintered at1240oC for4h, εr=37.4, tanδ=0.03%.（2）2-2type Ba2Ti9O20-BaFe12O19composite ceramics had been fabricatedsuccessfully by tape casting. The composites exhibit high dielectric constant andloss, lower saturation magnetization and remnant magnetization a highercoercive field compared with pure Ba2Ti9O20. The results show that the dielectricconstant firstly increases and then decreases, while the dielectric loss has anopposite variation, the saturation magnetization, the remnant magnetization andthe coercive field decrease with increasing sintering temperature. The compositesintered at1180oC for4h has optimum dielectric and magnetic properties, εr=115,tanδ=0.0054, Ms=21.9Am2/Kg, Mr=12.5Am2/Kg and Hc=63.0KA/m. |
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