Influence of Cd doping on the electro-strain of barium zirconate titanate ceramics

Cadmium doped barium zirconate titanate (Ba1-x,Cd-x(Zr0.13Ti0.87)O-3 (BCDZT) ferroelectric ceramic compositions with x=0, 0.02, 0.04 and 0.06 have been prepared by solid state reaction method. X-ray diffraction studies reveal a pseudocubic structure. For increasing Cd content, the bulk ceramic micro-structure reveals an increasing grain size and density. Variations in the dielectric, piezoelectric and unipolar electric field induced strain characteristics are discussed. Increasing Cd content reduces the coercive field, increases the remnant polarization and does not affect the ferroelectric-paraelectric phase transition temperature (similar to 60 degrees C). An optimum Cd content x=0.06 produces highly resistive ceramics with low dielectric loss (tan delta=0.019), and a maximum value of piezoelectric charge constant d(33)=114 pC/N and unipolar electro-strain of similar to 0.07%.