| Relaxor-ferroelectric materials are characterized by a high dielectric permittivity, a low loss, a high breakdown strength and a good temperature stability, which are suitable for applications in capacitors with high energy and high power density. In this paper, PMN-PT thick film and ceramic materials were successfully fabricated, the influence of sintering process, components and the doping of sintering aids on phase structure, ferroelectric, dielectric properties, energy-storage density and efficiency were investigated.The PMN-PT powders were synthesized with Swart-Shrout method by two-step. The frst stage, the columbite precursor MgNb2O6was calcined at1100℃for4h to ensure the complete formation of columbite. The second stage was the formation of the perovskite phase PMN-PT powders, which had been fabricated under850℃for2h.PMN-PT thick film materials were prepared on alumina substrates via screen printing method. The dielectric breakdown strength (DBS) of obtained PMN-PT thick film which was processed at850℃for2h is520kV/cm, energy-storage density is1.4J/cm3, and the storage efficiency is to22.7%. The effect of composition adjusting and the sintering on the energy storage properties of thick film are investigated. With the content of PT decreasing, it was found that the energy density as well as the dielectric constant of thick film was improved at room temperature by adjusting the composition of PMN and PT. The addition of Pb3O4could compensate for the volatilization of lead during sintering and improve the density of material. As a result, the addition of Pb3O4improves the breakdown strength of materials and the energy storage properties of thick film. The maximum recoverable energy-storage density and effciency of sample with3wt%Pb3O4were1.9J/cm3and25.7%under700kV/cm.PMN-PT bulk ceramic was also successfully prepared by solid state reaction in this work. The result of ceramic sintering process optimization experiment showed that the0.9PMN-0.1PT ceramics with dielectric breakdown strength of80kV/cm, the maximum energy-storage density of0.47J/cm3, and the energy-storage efficiency of45.8%were obtained by sintering at1225℃for2h. With the decreasing content of PT, we found that the energy-storage density and efficiency of ceramics at room temperature was improved by adjusting the composition of PMN and PT. As a result, the huge recoverable energy-storage density of0.8J/cm3and efficiency of70.3%under80kV/cm was obtained in0.96PMN-0.04PT ceramics. What’s more, the effects of different amounts of PbO-B2O3-SiO2-ZnO(PBSZ) glass additive on the0.96PMN-0.04PT ceramics were investigated. The results show that liquid phase sintering of0.96PMN-0.04PT ceramics with PBSZ glass additive decreased the porosity, increased the densification of ceramics and introducted the second phase, which resulting in decrease of the dielectric constant quickly. And doped PBSZ glass additive also lead to the energy-storage density of PMN-PT ceramics decrease. |
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