| With the rapid development of modern communication technology,in order to realize the miniaturization,light weight and integration of microwave devices,Low Temperature Co-fired Ceramic(LTCC)technology has been widely researched.Moreover,vanadium-based ceramics are becoming a research hotspot due to their excellent dielectric properties,low sintering temperature and low-cost preparation process.In this paper,the dielectric properties of BaMnV2O7 ceramics in vanadate system were reported for the first time.The modification of SrZnV2O7 and BiCaVO5 microwave dielectric ceramics were systematically studied by ion substitution method.The specific research results are as follows:BaMnV2O7 ceramic was prepared by solid-state reaction whose microwave dielectric properties were first reported:εr=11.17,Q×f=20040 GHz,τf=-48.2 ppm/℃.Trace amount of second phase in samples was identified by X-ray Diffraction method.Based on the Rietveld spectrum fitting method,the structure parameters of BaMnV2O7 at different sintering temperatureswere obtained.TEM analysis further concluded that BaMnV2O7 ceramics belongs to the P21/n space group with monoclinic structure.The influence of porosity on dielectric constant and Q×f value of BaMnV2O7 ceramics was systematically investigated.The change of τf value was explained by the V-O bond valence.In addition,the intrinsic dielectric properties of BaMnV2O7 ceramic were obtained by analyzing the far-infrared spectroscopy.BaMnV2O7 ceramics and silver electrodes can be co-fired at low temperature.which can become the potential application in the field of LTCC.The variation of the dielectric properties of SrZnV2O7 by Ni2+ substituted Zn2+was investigated.XRD showed SrZn1-xNixV2O7(X=0,0.01,0.02,0.03)ceramics are pure phases at different sintering temperature.The crystal parameters of the ceramics are obtained by fitting the refined XRD patterns.The variation of the dielectric constant mainly depends on the porosity and polarizability of the ceramics.The change of the Qxf value also has a strong correlation with the porosity.The optimum dielectronic properties of SrZnV2O7 was obtained at 740℃:εr=11.4,Q×f=49541GHz,τf=27.8ppm/℃,which achieved low temperature co-firing with silver electrode.The properties of SrZn0.99Ni0.01 V2O7 ceramics at X=0.01 are εr=11.81,Q×f=55091GHz,τf=-36.4ppm/℃.BiCaVO5 ceramics were prepared by solid-state reaction.The XRD pattern showed that it was a pure phase.The structure parameters of BiCaVOs was obtained by the Rietveld fitting method.The crystal structure of BiCaVOs ceramics indicated that the ceramics belonged to the orthogonal structure of the Pbca space group.The vibration characteristics of BiCaVO5 ceramics were studied by Raman spectroscopy,and the intrinsic dielectric properties of BiCaVO5 ceramics were obtained by far-infrared spectroscopy.The effect of porosity on the εr and Q×f value were analyzed and its dielectric properties at 860℃ the optimum sintering temperature are:εr=16.44,Q×f=55388GHz,τf=-66.4 ppm/℃.In addition,BiCaVOs was able to coexist with silver electrodes.BiCa1-xMnxVO5(X=0.02,0.04,0.06)was prepared by solid state reaction.The phase structure,microstructure and dielectric properties of BiCa1xMnxVO5(X=0.02,0.04,0.06)ceramics were analyzed by XRD,SEM,EDS and other characterization methods.The properties of BiCa0.98Mn0.02VO5 ceramics at 820℃ are εr=15.8,Q×f=60716GHz,τf=-56ppm/℃ with the final Mn2+substitution X=0.02,which improves the dielectric properties and reduces the sintering temperature.Based on the excellent dielectric performance,the device simulation experiment was carried out with HFSS software and a dielectric resonant antenna was designed to realize the engineering application of dielectric ceramics. |
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