Dielectric, ferroelectric, and piezoelectric properties of Nb-substituted Bi1/2(Na0.82K0.18)1/2TiO3 lead-free ceramics

Incipient piezoelectrics and electrostriction behavior in Sn-doped Bi1/2(Na0.82K0.18)1/2TiO3 lead-free ceramics

“…All the characteristic parameters such as the maximum polarization (P max ), the poling strain (S pol ), the remanent polarization (P rem ), and the remanent strain (S rem ) decrease with increasing x, indicating that the addition of Sn suppresses a field-induced FE order, which conforms to the previous observations in modified BNKT systems. [4][5][6][7][8][9][10] It is seen that there happens a significant increase in (S pol -S rem ) at x ¼ 0.05, beyond which it decreases drastically. The value of (S pol -S rem ) corresponds to the maximum available strain (S max ) when the material is used as electromechanical actuator.…”

“…1,2 Since a giant electric-field-induced strain was reported by Zhang et al 3 in Bi 1/2 Na 1/2 TiO 3 -BaTiO 3 -(K 1/2 Na 1/2 )NbO 3 (BNT-BT-KNN) ceramics, great attention has been paid to (Bi 1/2 Na 1/2 )TiO 3 (BNT)-based perovskite ceramics in expectation for large-stroke actuator applications such as fuel injectors and vacuum circuit breakers. A common strategy so far was to incorporate a small amount of additional chemical entities such as single isovalent dopants, 4,5 donors, 6,7 or ABO 3 -type compounds [8][9][10] into BNT-BT or BNT-(Bi 1/2 K 1/2 )TiO 3 (BKT) solid solution systems at the so-called morphotropic phase boundary (MPB). 11,12 Here, we use the term, giant strains, to distinguish them from the conventional electric-field-induced strain in poled ferroelectric (FE) materials in that the onset of these strains requires a certain threshold electric field level (referred to as E pol hereafter), but this electric-field-induced poling state becomes unstable with little trace of perceivable piezoelectricity when the field is removed.…”