Large Electrostrain in K(Nb1-xMnx)O-3 Lead-Free Piezoelectric Ceramics

Abstract

K(Nb1 - xMnx)O-3 (KN1 - xMx) ceramics with 0.005 <= x <= 0.015 were sintered at 1020 degrees C through a normal sintering process without the formation of a liquid phase. They exhibited double polarization versus electric field (P-E) hysteresis and sprout-shaped strain versus electric field (S-E) curves owing to the presence of a defect dipole (P-D), which was formed between the acceptor Mn3+ ion and the oxygen vacancy. Moreover, the aging process was not required to develop the P-D. The KN1 - xMx ceramics exhibited a large strain of similar to 0.2% at 6.0 kV/mm. For the KN0.985M0.015 ceramic, this large strain was maintained after 10(4) cycles of an electric field of 6.0 kV/mm. This ceramic also maintained a double hysteresis curve at 200 degrees C. Therefore, the KN0.985M0.015 ceramic has a large electric field-induced strain, along with good thermal and fatigue properties for multilayer piezoelectric actuators.