Effect Of Yttrium Doping On The Structure And Piezoelectric Properties Of BCT-BZT Lead-free Ceramic

Ferroelectric piezoelectric materials have become one of the important functional materials because of their good piezoelectric properties,ferroelectric and pyroelectric properties and are widely used in the memory,sensors,communication equipment and transducers.At present,the most outstanding,the most widely used ceramic materials are lead zirconate titanate ceramic materials.However,its raw materials containing lead elements,will cause environmental pollution in the production and disposal process.Lead-free piezoelectric ceramics that can replace lead-based materials have become one of the focus of researches.A non-Pb pseudobinary ferroelectric system Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)Ti O3,named BZT-BCT,lead-free piezoelectric ceramics has the superior performance and its homogeneous phase boundary region can be adjusted by the composition design.It attracts the attentions of the majority of scholars and it has become one of the alternatives to lead-based ceramic materials.Doping modification is a common method to improve the performance of ceramic materials.By introducing appropriate dopants,certain properties of the ceramic can be improved.In this paper,yttrium oxide was chosen as the dopant.The effect of yttrium on the properties of BZT-BCT ceramics was studied.In this paper,50BCT-50 BZT lead-free ceramics were prepared by traditional solid-state reaction method and the sintering properties of ceramics were explored.The samples were analyzed by phase analysis and the samples show typical ABO3 perovskite structure and there was no impurity phase formation.The doped Yttrium was successfully dissolved into the lattice of 50BCT-50 BZT ceramics,and formed a uniform and stable solid solution.It was observed that the introduction of yttrium dopant made ceramic pores decrease and density increase by scanning electron micrographs.The relative dielectric constant and dielectric loss of samples at different temperatures and different frequencies were measured.And it is found that the introduction of yttrium can improve the dielectric properties of ceramic samples.At the frequency of 100 Hz,the relative dielectric constant of the ceramic samples doped with 0.6 mol% was the highest,about 2175.With the increase of yttrium doping content,the loss of ceramic samples increased slightly.The effect of yttrium on the ferroelectric and piezoelectric properties of 50BCT-50 BZT ceramics was investigated by testing the ferroelectric and piezoelectric properties of the samples.With the increase of the doping content,the polarization intensity of the sample increases first and then decreases.When the doping content is 0.4 mol%,the sample has the largest remanent polarization,Pr =6.38 ?C/cm2 The inverse piezoelectric coefficient d33* is calculated from the butterfly curve of the strain / voltage of the ceramic sample.With the increase of yttrium doping content,the inverse piezoelectric coefficient of the sample first increases and then decreases.When the doping content is 0.2 mol%,the sample has the largest inverse piezoelectric coefficient,d*33 =494 pm/V.