Research On Fabrication And Properties Of PIN-PMN-PT Textured Ceramics By Templated Grain Growth

In recent years,relaxor-based Pb(In_1/2Nb_1/2)O₃-Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃（PIN-PMN-PT）ferroelectric single crystals have attracted much attention due to its excellent piezoelectric properties and strain response along the（001）direction,as well as its high Curie temperature,phase transition temperature and large coercive field.However,the complex preparation process,low yield and long period limited its wide application.Template grain growth（TGG）technology can greatly improve the electrical properties of piezoelectric ceramics with<001>orientation,and the preparation process is simple and suitable for large-scale production.In this paper,platelike PbTiO₃（PT）templates were prepared by topochemical molten salt synthesis（TMSS）.And on this basis,plate-shaped Pb(Zr_xTi_1-x)O₃（PZT）grains were synthesized for the first time.Then,0.36PIN-0.30PMN-0.34PT textured ceramics with<001>orientation were prepared by using PT templates as seed crystals and TGG technology.The preparation process and properties of the template and textured ceramics were systematically studied.In the process of preparing platelike PT templates by using TMSS,through adjusting the sintering conditions,pickling concentration and excessive PbO in the synthesis process of PbBi₄Ti₄O₁₅ precursors and templates,the platelike PT template with<001>oriented pure perovskite structure was obtained.Its radial size was 5¹5μm,thickness was 0.3⁰.5μm,and aspect ratio was10³0,which met the selection requirements of template materials.On this basis,<001>oriented platelike PZT grains with different Zr/Ti ratios were synthesized by using the method of TMSS for the first time.It was found that when the Zr/Ti ratio was 5:5,the PZT was near the morphotropic phase boundary,and the optimum platelike morphology was obtained.The radial size was 1⁵μm and the thickness was about 0.2μm,which laid a solid foundation for the development of PZT-based textured ceramics.In the process of fabricating textured ceramics by TGG technology,high-quality ceramic green tape with a thickness of 45-65 um was prepared by adjusting the technological parameters of tape casting.Then,textured ceramic green with well-tiled and uniformly dispersed templates were successfully fabricated after lamination.Subsequently,PIN-PMN-PT textured ceramics with high orientation were prepared by changing the addition of PT template and sintering temperature.The results showed that when the template content was 5 wt%,the textured ceramics obtained after holding for 5 h at 1250℃had the highest Lotgering factor of 63%with<001>orientation.The bulk density and relative density were 7.8641 g/cm³ and 96%,respectively.The quasi-static piezoelectric constant d₃₃ was 658 pC/N,and a large strain S_max of 0.653%was achieved from unipolar S-E under an electric field of 50 kV/cm,corresponding to a high-field coefficients d^*₃₃ of 1306 pm/V.Furthermore,the transition temperature T_R-T and Curie temperature T_C were 196℃and 261℃,respectively.Compared with random oriented ceramics(d₃₃⁴33 pC/N,S_max⁰.206%,d^*₃₃⁴12pm/V,T_R-T¹74℃,T_C²43℃),the properties of textured ceramics have been greatly improved.In terms of ferroelectric properties,the residual polarization P_r of 26.1μC/cm²,and the coercive field E_C of 12.3 kV/cm were slightly weakened.However,compared with the traditional PMN-PT relaxor ferroelectric materials,E_C was nearly its twice.Therefore,0.36PIN-0.3PMN-0.34PT textured ceramics can be used at higher temperature and electric field because of its high temperature stability as well as better strain response and piezoelectric properties under high electric field.