Large Electrostrain in K(Nb_1−xMn_x)O₃ Lead‐Free Piezoelectric Ceramics

Abstract

K(Nb1−xMnx)O3 (KN1−xMx) ceramics with 0.005 ≤ x ≤ 0.015 were sintered at 1020°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 (PD), which was formed between the acceptor Mn3+ ion and the oxygen vacancy. Moreover, the aging process was not required to develop the PD. The KN1−xMx ceramics exhibited a large strain of ~0.2% at 6.0 kV/mm. For the KN0.985M0.015 ceramic, this large strain was maintained after 104 cycles of an electric field of 6.0 kV/mm. This ceramic also maintained a double hysteresis curve at 200°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.

Characterization and comparison of grain boundary character distributions in cemented carbides with different binder phases

“…The crystallographic configuration of 90°/[10 À10] boundary can be speculated to has a significant effect on the performances of cemented carbides, mainly because the (0 0 0 1) basal and (10-10) prismatic facets of carbide crystals are different in either surface energy [8] or micro-properties [2]. Earlier works suggest that the 90°/[10 À10] boundaries can either pre-exist in the raw powder and be eliminated during sintering [10,11], or be evolved by the coalescence of low-energy crystallographic facets [8]. The outcome of current work illustrates that 90°/[10 À10] boundaries are the most frequently occurring carbide/carbide boundaries in cemented carbide samples with either cobalt or nickel as the binder phase (see Fig.…”

“…Among these boundaries, the 90°/[10 À10] boundary, with the basic crystallographic feature of a 90°rotation about the [10 À10] axis [7], and with low interfacial energy as well as high work of separation [8], is attracting special attention [6,[9][10][11][12][13]. Note that the hexagonally close packed lattice structure of tungsten carbide has a c/a ratio of 0.976 (here c = 0.2837 nm and a = 0.2906 nm) [14] which is quite close to 1, so the 90°/[10 À10] boundary can be referred to as R2 boundary in coincidence site lattice (CSL) notation [7], where the low R value represents high reciprocal density of coinciding sites and symmetrical configuration of dense planes [15].…”

Piezoelectric properties of (Na0.5K0.5)(Nb1‐xSbx)O3‐SrTiO3 ceramics with tetragonal‐pseudocubic PPB structure

“…These lead‐free piezoelectric ceramics can be used for piezoelectric actuators. The large strain observed in these ceramics is attributed to the formation of a sprout‐shaped strain vs electric field ( S‐E ) curve without remnant strain . For (Bi,Na)TiO 3 ‐based Pb‐free ceramics, this sprout‐shaped S‐E curve is explained by a phase transition between an ergodic relaxor state and a ferroelectric state upon the application of an electric field .…”

“…Several investigations have been also conducted on (Bi,Na)TiO 3 ‐based and acceptor‐doped Pb‐free piezoelectric ceramics because they showed large electric field‐induced strain . These lead‐free piezoelectric ceramics can be used for piezoelectric actuators.…”

Production of Si3N4/Glass Composites for LTCC Substrate by Aqueous Tape Casting Process

“…In recent years, the systems consisting of Al 2 O 3 filler and glass have been studied extensively. Besides the Al 2 O 3 system, a large number of works have been carried out on the LTCC system including various glass and ceramic filler materials, such as cordierite glass/AlN, borosilicate glass/AlN, calcium aluminoborosilicate glass/BN, calcium aluminoborosilicate glass/AlN, calcium aluminoborosilicate glass/Si 3 N 4 , calcium aluminoborosilicate/CaCu 3 Ti 4 O 12 , and cordierite glass/AlN; however, the preparation process do not discussed in the works mentioned above.…”