Improvement On Poling Property Of 0-3 Ceramics/Polymer Piezoelectric Composites

0-3 ceramic/polymer piezoelectric composites are widely used in the fields of hydroacoustic transducers,medical sensors and so on due to its high mechanical strength,low acoustic impedance and good matching ability with water and organisms.The piezoelectric ceramics phase in the 0-3 piezoelectric composites mainly distributes in the form of grains and the large difference between the dielectric constants of ceramics and polymer results in low poling voltage applied on the ceramics phase during the poling process.So it's difficult to pole 0-3 ceramic/polymer piezoelectric composites.In order to improve the poling property of 0-3 ceramic/polymer piezoelectric composites,the poling approach can be changed or the poling voltage applied on the ceramics phase can be improved.In this work,two ways were proposed to improve the poling property of 0-3 ceramic/polymer piezoelectric composites.First,lead stibium zirconate titanate(PSZT) piezoelectric ceramics with low curie temperature were prepared via doping barium into PSZT piezoelectric ceramics,then 0-3 PSZT/PVDF piezoelectric composites were prepared and poled by a high temperature poling method.Second,a model for 0-3 piezoelectric composites with an interlayer was established,then calcium titanate(CaTiO₃) as the interlayer was introduced into the 0-3 PZT/PVDF piezoelectric composites to improve the poling property of the composites.The PSZT ceramics with compositions of 0.98Pb_1.0-xBa_xTi_0.48Zr_0.52O₃-0.02PbSbO₃(x=0.14～0.24) have been prepared by a conventional solid reaction process.The barium doping leads to the changes of PSZT ceramics' structure, curie temperature,dielectric property and piezoelectric property.It is found that as the barium content around 0.22,the PSZT ceramic specimen is characterized with a low curie temperature 156℃,and satisfied dielectric and piezoelectric properties with the relative dielectric constant 5873,dielectric loss factor 0.0387, piezoelectric strain constant 578 pC/N.0-3 PSZT/PVDF piezoelectric composites with low curie temperature have been prepared by self-made slobbering device and poled with high temperature poling method.The analysis of XRD and piezoelectric strain constant indicates that the poling property of the piezoelectric composites can be improved by improving the final poling voltage,compared with the regular poling method,high temperature poling method can low the poling voltage of piezoelectric composites.A model for 0-3 piezoelectric composites with an interlayer has been developed and the preliminary expressions for this model consequently have been derived based on the Furukawa's model of 0-3 piezoelectric composites without interlayer.Effects of the interlayer volume fraction,the dielectric constant ratio of interlayer and polymer matrix on the electric field in ceramic are analyzed. The predicted results show that the electric field on ceramic and composite dielectric constant can be improved by introducing an interlayer with appropriate volume fraction and dielectric constant into the 0-3 piezoelectric composite.PZT piezoelectric ceramics powders have been coated with calcium titanate (CaTiO₃) of different volume fractions.0-3 PZT/PVDF piezoelectric composites with the CaTiO₃ interlayer(the volume fractions of CaTiO₃ are 0%,7%,14%, 21%,28%and 35%) have been prepared.When the volume fraction of CaTiO₃ is below 21%,the experimental and theoretical dielectric constants are generally consistent,but when the volume fraction of CaTiO₃ is above 21%,the deviation between experimental and theoretical data occurs.When the volume fraction of CaTiO₃ increases from 0 to 14%,the piezoelectric strain constant of the 0-3 PZT/PVDF piezoelectric composites increases from 12.4 to 17.2 pC/N.So that, introducition of CaTiO₃ interlayer with appropriate volume fraction can improve the poling property of 0-3 piezoelectric composites.