Large and Stable Shape Memory Effect Realized by Defect Dipoles in Acceptor‐Doped Ferroelectric Ceramics

Abstract

A large and stable shape memory effect has been observed in 0.6 wt% Mn‐doped (Pb0.99Nb0.02)[(Zr0.70Sn0.30)0.52Ti0.48]0.98O3 (Mn:PNZST) ceramics after being poled at high temperature. A maximum shape memory of 0.41% was achieved. This effect is related to the preferentially oriented defect dipoles along the poling direction after poling at high temperature and electric field. Furthermore, the shape memory effect is stable after 104 electric cycles at 30 kV/cm. The shape memory piezoelectric actuator may be fabricated using this kind of material.

Defect‐driven evolution of piezoelectric and ferroelectric properties in CuSb2O6‐doped K0.5Na0.5NbO3 lead‐free ceramics

“…[1][2][3][4][5] For acceptor doping, oxygen vacancies are created due to the requirement of charge balance and can form defect dipoles with acceptor ions. have an important influence on their properties.…”

“…In terms of Pb(Ti, Zr)O 3 -based ceramics, the substitutions of Pb 2+ or (Ti, Zr) 4+ by low valent ions of K, Mn, or Fe ions (i.e., acceptor doping) harden the ceramics, giving high mechanical quality factor Q m , low loss tangent tand, and slanted polarization hysteresis loop and high coercive field. [1][2][3][4][5] For acceptor doping, oxygen vacancies are created due to the requirement of charge balance and can form defect dipoles with acceptor ions. These defects play a significant role in stabilizing domain patterns and inducing hardening behavior of the ceramics for various applications in high-power and high-voltage fields.…”

“…These defects play a significant role in stabilizing domain patterns and inducing hardening behavior of the ceramics for various applications in high-power and high-voltage fields. [1][2][3][4][5][6] In addition, macroscopic properties (i.e., switching behavior, 7,8 fatigue, 9,10 aging, 11,12 etc.) of piezoelectric materials are closely related to the defects caused by acceptor doping.…”

Enhanced and stable strain memory in Mn‐doped Pb(Mn1/3Sb2/3)O3–Pb(Zr,Ti)O3 ceramics realized by sesquipolar loading

“…However, this process is quite complicated and the achieved strain memory exhibits serious fatigue problems, which undoubtedly limits its application. 4 Analogous to the imprint electric field, the introduction of internal bias field (E bias ) during poling and aging process in hard type PZT materials, 5,6 2,7 E bias observed in hard type PZT materials is supposed to be related with preferentially oriented defect dipoles along the poling direction. 2,7 On the other hand, from the viewpoint of loading method of applied electric field, sesquipolar loading, referring to the situation where the external field is cycled between a positive electric field E + and a smaller negative electric field E À , is an effective way to increase strain output of piezomaterials.…”

“…4 Analogous to the imprint electric field, the introduction of internal bias field (E bias ) during poling and aging process in hard type PZT materials, 5,6 2,7 E bias observed in hard type PZT materials is supposed to be related with preferentially oriented defect dipoles along the poling direction. 2,7 On the other hand, from the viewpoint of loading method of applied electric field, sesquipolar loading, referring to the situation where the external field is cycled between a positive electric field E + and a smaller negative electric field E À , is an effective way to increase strain output of piezomaterials. [8][9][10] For example, it was reported that effective strain of 0.33% was obtained when sesquipolar singal was applied to soft type PZT ceramics, which was two times higher than the unipolar strain.…”