| The key to the preparation of the high energy storage density and large value capacitor is to seek a kind of material with the properties of energy storage density and high energy storage efficiency(low energy loss) and rapid store or release electrical behavior simultaneously. Pb-based antiferroelectrical material is the phase transition material with such properties, and it can realize the rapid transition from antiferroelectrical state(AFE) to paraelectric state(P) and AFE to ferroelectric state(FE) induced by temperature, electric field or stress, showing a double hysteresis loop, and the energy be storaged or released.Sol-Gel method was selected to synthesis Pb-based antiferroelectrical ceramic powder with single perovskite structure and differnt components, and the ceramics be sinted into ceramics. Differential thermal-thermo gravimetric analyzer(DSC-TG), X-ray diffraction(XRD), scanning electron microscopy(SEM) and ramam tester(Ramam) was used to ascertained the structure of the ceramic powder, dielectric properties tester and ferroelectric properties tester were used to test the electrical properties of ceramic. The influence of excessive Lead, the types and contents of additives on the structure and micromorphology of Pb-based ceramics powder were discussed. The optimal process parameters for synthesizing PZ with single perovskite structure were obtained. The doping modification of La3+, Ti4+, and the mixture of La3+ and Ti4+ on the synthesis temperatures, grain size,micromorphology and electrical properties of Pb-based antiferroelectrical ceramics powder were investigated.PZ ceramic powder with different excessive Pb were prepared with Sol-Gel method.The experimental results showed that the optimum value of lead excess is 3%. Calcinated at 900℃ and holding for 2h, PZ ceramics powder with single perovskite structure were synthesized, but the powder agglomeration phenomenon is serious.Considering the high synthesis temperature and serious agglomeration phenomenon of the powder, the effects of the addition of DEA and PEG on the phase transition temperatures, grain size and particle morphology of PZ ceramics powder were studied. It founds that the addition of DEA helps to reduce the synthesis temperature of PZ ceramic powder with single perovskite structure. Adding 10% DEA, the synthesis temperature ofPZ ceramics powder(Pb excess3%) is 580℃, while that for PZ is 900℃ without the addition of DEA. Adding 10% PEG helps the dispersion of PZ ceramics powder.The results of element doping modification indicated that the addition of La3+, Ti4+caused lattice distortion of Pb-based antiferroelectric materials, leading to the grain refinement and descreasing the synthesis temperature. The synthesis temperature of PLZ,PZT, PLZT ceramics powder is 540℃, 600℃ and 580℃ respectively, and the theoretical calculation value of grain size is 35.47 nm, 47.50 nm and 45.43 nm.Ramam test illustrated that at room temperature, the phase structure of PZ and PZT are antiferroelectric orthorhombic phase, while that for PLZ and PLZT are antiferroelectric tetragonal phase.The electrical properties test results reflected that the Curie temperature of PZ, PLZ,PZT, PLZT are 226 ℃, 151 ℃, 230 ℃ and 148 ℃ respectively, their dielectric constants are 2264, 3489, 2641 and 3196, the electrical strength of field induced switching are EA-F=13.4 KV/cm,9.9 KV/cm, 12.1 KV/cm and 7.4 KV/cm, while EF-A=10.2 KV/cm, 6.6KV/cm, 7.4 KV/cm and 3.8 KV/cm, and its saturation polarization PS are 11.28 UC/cm2,12.26 UC/cm2, 19.41 UC/cm2 and 22.49 UC/cm2. |
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