Evolution of piezoelectric response in (1-x)KNbO3-x(Ba0.5Bi0.5)(Nb0.5Zn0.5)O3 ceramics

Dense (x)KNbO3-x(Ba1/2Bi1/2)(Zn1/2Nb1/2)O3 (0 ≤ x ≤ 0.25) ceramics were prepared by the solid state reaction method. X-ray diffraction data show the average crystal structure to evolve from orthorhombic at x = 0 to pseudocubic at x = 0.25. Raman spectroscopy suggests the absence of polar order for x ≥ 0.25 ceramics. Polarisation versus electrical field measurements show a continuous decrease in the spontaneous polarisation with increasing x. Electrical-field-induced strain measurements reveal a piezoelectric-to-electrostrictive crossover. An electrostriction coefficient of 0.043 m4/C2 was measured for x = 0.15.