Research On Texturing PT/PZT-based Piezoelectric Ceramics By Templated Grain Growth

With the development of science and technology,classical piezoelectric ceramics have not been able to meet the requirement of market.In the recent years,textured ceramics have sparked extensive interests of the researchers because of their simple preparation method,low costs and excellent electromechanical properties and they have widely used in the field of actuators,sensors and transducers.In this paper,BaTiO₃ template was primarily prepared by molten salt and topological chemical microcrystal conversion method and then the textured 0.675Pb(Mg_1/3Nb_2/3)O₃-0.325PbTiO₃?PMN-PT?and 0.4Pb(Mg_1/3Nb_2/3)O₃-0.25PbZrO₃-0.35PbTiO₃?PMN-PZT?ceramics were synthesized by templated grain growth technique.The preparation technology of templates and textured ceramics and the influences of templates to the properties for textured ceramics were systematically studied.BaTiO₃ template with<001>orientation?f?98%?was obtained by appropriate heating temperature,cooling rate and pickling conditions at each stage during the synthesis of Bi₄Ti₃O₁₂,BaBi₄Ti₄O₁₅ and BaTiO₃.The platelet BaTiO₃ template was perovskite structure without any impurities and exhibited obvious anisotropy.The length and width dimensions of BaTiO₃ template were 5¹5?m and the thickness was 0.5¹?m.The ratio of two dimensions was over 10,indicating BaTiO₃ templates were suitable to elicit the oriented growth of the grain.PMN-PT green tape and textured ceramics were prepared by tape-casting process and templated grain growth technology,respectively.It was found that highly oriented PMN-PT textured ceramic with a maximum Lotgering factor f of 66%was obtained when sintered at 1180oC for 5 h and the addition amount of BaTiO₃ template was 6 wt%.The density and relative density of PMN-PT textured ceramic were 7.6896 g/cm³ and 95%,respectively.The quasi-static piezoelectric coefficient d₃₃3 was615 pC/N.Furthermore,a large strain S_m of 0.317%was achieved from unipolar S-E under an electric field of 40 kV/cm,corresponding to a high-field coefficients d^*₃₃ of 793 pm/V.The piezoelectric coefficients of textured ceramic were larger than those of random oriented ceramic(d₃₃⁴03 pC/N,d^*₃₃⁴55 pm/V),indicating an enhancement in piezoelectricity.Besides,the addition of BaTiO₃template had little influence on Curie temperature T_c,which was around 150oC for the textured ceramics with different Lotgering factor.PMN-PZT textured ceramics were prepared in the same method mentioned above with a Lotgering factor f of 56%.The quasi-static piezoelectric coefficient d₃₃,strain S_m,high-field coefficients d^*₃₃,remanent polarization and coercive electric field were 432 pC/N,0.257%,643 pm/V,41.44?C/cm² and 9.99 kV/cm,respectively.All the crucial physical parameters of textured ceramic were better than those of random oriented ceramic(d₃₃³53 pC/N,S_m⁰.196%,d^*₃₃⁴90 pm/V?P_r²5.97?C/cm,E_c¹1.2 kV/cm).Moreover,both of T_c for textured and random oriented ceramic were about 210oC.Therefore,ceramic texturation could improve the piezoelectric properties at the lowest expense of reducing T_c.