Bulk dense fine-grain (1-x)BiScO3-xPbTiO3 ceramics with high piezoelectric coefficient

High density fine grain (1-x)BiScO3-xPbTiO(3) ceramics were successfully prepared by two-step sintering and their ferroelectric properties were investigated. Experimental evidence indicates the existence of a morphotropic phase boundary at the composition x=0.635, which exhibits a piezoelectric coefficient d(33) of 700 pC/N at room temperature, significantly higher than the reported values to date. Furthermore, a higher electromechanical coupling factor Kp=0.632 and a larger remnant polarization P-r=47.3 mu C/cm(2) were obtained. The paraelectric-to-ferroelectric phase transition occurs at 446 degrees C, slightly lower than in the coarse grain ceramics with a similar composition, suggesting a grain size effect. The local effective piezoelectric coefficient d(33)(*) was estimated to be 795 pC/N at 2.29 V, measured by scanning probe microscopy. Further atomic force microscope observation revealed the existence of 90 degrees domains of about 60-70 nm in width, confirming the previous results that small domain structure enhances the piezoelectric properties.