Evolution of piezoelectric response in (1-x)KNbO_(3-x)(Ba_(0.5)Bi_(0.5))(Nb_(0.5)Zn_(0.5))O_3 ceramics

摘要

Dense (1-x)KNbO_(3-x)(Ba_(1/2)Bi_(1/2))(Zn_(1/2)Nb_(1/2))O_3 (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 m~4/C~2 was measured for x = 0.15.