Aided Sintering And Piezoelectric Performances Of BCT-BCT Lead-free Ceramics

Ferroelectric ceramic is a kind of functional ceramic that can transform electric energy and mechanical energy into each other,and it is widely used.Over the past few decades,the lead-based piezoelectric ceramics PZT dominantly occupy the market of piezoelectric ceramics.Though it has excellent properties,the hazardous pollution holdback its application.Therefore,it is significant to explore excellent performances of lead-free piezoelectric ceramics.x(Ba0.7Ca0.3)Ti O3-(1-x)Ba(Zr0.2Ti0.8)O3(abbreviated to x BCT-(1-x)BZT or BCZT),environmental materials,ceramics have outstanding electrical properties.However,the shortcomings such as the high sintering temperature,high cost,low economy hinder its potential development.The previous investigations indicates that BCZT lead-free piezoelectric ceramics have large piezoelectric coefficients near the morphotropic phase boundary,the optimal sintering temperature can be reduced by suitable sintering aids,the electrical properties could be also improved.In this work,0.48[(Ba0.7Ca0.3)Ti O3]-0.52[Ba(Zr0.2Ti0.8)O3] ceramic materials were prepared by the conventional solid-state reaction method.The sintering characteristics and dielectric,piezoelectric,ferroelectric properties from 1350 ? to1450 ? was explored.The results showed that the samples sintered at 1350 ?,1370 ?,1430 ? and 1450 ? presented pure perovskite structures.The pyrochlore phase appeared in the samples at the sintering temperature of 1390 ?and 1410 ?.The samples sintered at 1430 ? achieved the best performance: the density was5.267 g/cm3,the remanent polarization was 10.24 ?C/cm2,the piezoelectric constant(d33)was 413 p C/N and the reverse piezoelectric coefficient(d33*)was 790 pm/V.Based on this,in this paper,Li Nb O3 and Na Cl were chosen as sintering aids to investigate the influence of different doping concentrations on the sintering and electrical properties of 0.48 [(Ba0.7Ca0.3)Ti O3]-0.52[Ba(Zr0.2Ti0.8)O3].The results showed that 0.2wt% Li Nb O3 sintering aids can reduce the sintering temperature ofBCZT ceramic from 1430 ? to 1370?: the grain growth was uniform,the density was 5.472 g/cm3,the piezoelectric coefficient(d33)was 502 p C/N,the maximum polarization(Pmax)was 16.9 ?m/cm2,the remanent polarization(Pr)was 9.9 ?m/cm2 and the coercive field(Ec)was 3.32 k V/cm and the reverse piezoelectric coefficient(d33*)was 837 pm/V.Na Cl sintering aid with the concentration of 0.4wt%can reduce the sintering temperature of BCZT ceramic system from 1430 ? to1410 ?.The grains of the samples grew homogeneously with obvious liquid phase between the grains,the density was 5.472g/cm3,the piezoelectric coefficient(d33)was462 p C/N,the maximal polarization(Pmax)was 16.6 ?m/cm2,the remanent polarization(Pr)was 11.2 ?m/cm2,the coercive field(Ec)was 3.28 k V/cm and the inverse piezoelectric coefficient(d33*)was 852 pm/V.