The Influence Of Piezoelectric Phases On The Performances Of 1-3 Piezoelectric Composites

Piezoelectric composites are used widely in many fields,such as sensor,brake,transducer,etc.1-3 piezoelectric composites are the most important materials in the field of piezoelectric composites.Our team has researched on the process of fabricating 1-3 piezoelectric composites and piezoelectric fibers by extruding powder and sol.Influence of different piezoelectric phases on compo sites are mainly studied in this paper,thus preparing and Modifying piezoelectric powders, and study on properties of the composites prepared by modified piezoelectric powders.Variation of properties in composites are similar to piezoelectric fibers,thus properties of composites could be modified by modifying piezoelectric powders.The composites prepared by PZT5H(ternary system piezoelectric ceramic PMN-PZT) are better than other three kinds,Piezoelectric strain constant d₃₃ was 360 pC/N,piezoelectric voltage constant was 428.88,but its anisotropic property K_t/K_p was 1.735,which need to improved.To improve its anisotropic property,this paper choose PMN-PT as piezoelectric phases to modification.PMN-PT ceramics with compelx perovskite structure are prepared by secondary synthesis.The formation of pyrochlore phase is inhibited by secondary synthesis,meanwhile the synthesis temperature of perovskite phase is decreased, reducing the volatilization of PbO in maximum.The testing results show that:the density of 0.67PMN-0.33PT being prepared was 7.95g/cm3,and the piezoelectric strain constant was 450 pC/N.The research of doping modify in PMN-PT show that: when doping La³⁺ in 2mol%,piezoelectric strain constant,relative permittivity and anisotropic property of PMN-PT were greatly enhanced,permittivity loss and mechanical quality factor were slightly decreased.The effect of doping Sn⁴⁺ and Mn⁴⁺ were both enhancing anisotropic property and mechanical quality factor, decreasing permittivity loss and piezoelectric strain constant.The difference is that the former enhancing the relative permittivity,but the latter was contrary. 1-3 piezoelectric composite was prepared by PMN-PT which doping La³⁺ in 2mol%,and the results show that:the anisotropic property K_t/K_p,of composites was greatly enhanced,which was reached 2.45,the thickness resonance modle have no interference.Piezoelectric strain constant d₃₃ was 360 pC/N and piezoelectric voltage constant was 428.88,which were both relatively great.So it's a good sensor material.