Piezoelectric and Dielectric Properties of (Bi,Na,K,Ag)TiO₃–BaTiO₃Lead-Free Piezoelectric Ceramics

Abstract

Lead-free (1 À y )(Bi 0:5 Na 0:49Àx K x Ag 0:01 )TiO 3 -yBaTiO 3 (x ¼ 0 to 0.1, y ¼ 0 to 0.04) [abbreviated as BNKAT-BT-100x/100y] piezoelectric ceramics were fabricated using various amounts of K and Ba substitutions, and their piezoelectric and dielectric properties were investigated. The crystal structure significantly changed with the amount of K substitution. The BNKAT-BT-5/2 specimens exhibited a pseudocubic structure, while the BNKAT-BT-10/2 specimens exhibited a tetragonal structure and provided a larger electrostrain constant (d 33 Ã ) than BNKAT-BT-0/2 specimens, which exhibited a rhombohedral structure. The addition of La 2 O 3 /MnO to BNKAT-BT specimens affected the crystal structure and electrical properties. La 2 O 3 /MnO-added BNKAT-BT-10/100y (0:02 5 y 5 0:03) specimens with a pseudocubic structure exhibited P-E hysteresis loops different from those that are characteristic of ferroelectric, and provided a peculiar field-induced strain without the residual strain in the butterfly curve and a very large strain constant (d 33 Ã ) of 415 pm/V. This may be associated with the field-forced phase transition from the paraelectric phase to the ferroelectric phase.

Current Development in Lead-FreeBi0.5(Na,K)0.5Quan1, Bac2, Thiet3 et al. 2014Advances in Materials Science and Engineering

“…However, theoretical calculation indicated that the ultrahigh electromechanical response in single-crystal piezoelectrics resulted from polarization rotation during poling processing [54]. Coupling factor, k p (%) [57] BNKT-(Li, Ce) [59] BNKT-(Li, La) [61] BNKT-Nd [58] BNKT-La [56] BNKT-Ce [63] BNKT-Gd [65] BNKT-Ho [66] BNKT-Er [67] BNKT-Eu [62] BNKT-Sm [84]. Moreover, this group also pointed out that the addition of La 2 O 3 /MnO to BNKAT-BT specimens displayed a very large strain dynamic constant max / max of 415 pm/V which results from the field-forced phase transition from the paraelectric phase to the ferroelectric phase [84].…”

Enhanced piezoelectric properties of (Ba0.3Bi0.7)(Mg0.05Fe0.6Ti0.35)O3piezoelectric ceramics with high Curie temperature

“…1 Lead is, however, a toxic element, and therefore lead-free piezoelectrics have extensively been studied. [2][3][4][5][6][7][8][9][10][11][12] To date, no piezoelectric material with the piezoelectric response and Curie temperature simultaneously comparable to those of PZT was found. 13 The large piezoelectric responses of PZT are attributed to the morphotropic phase boundary (MPB), which separates tetragonal and rhombohedral phases.…”

Structure and electrical properties of (Bi0.5Na0.5)1–x–y–z(Bi0.5K0.5)xBay(Bi0.5Li0.5)zTiO3 lead‐free piezoelectric ceramics

“…In order to improve the poling process and enhance the piezoelectric properties of the BNT‐based ceramics, a number of BNT‐base solid solutions, such as BNT‐BaTiO 3 1, Li‐doped (Bi 0.5 Na 0.5 )TiO 3 ‐(Bi 0.5 K 0.5 )TiO 3 ‐BaTiO 3 2, Sr x (Bi 0.5 Na 0.5 ) 1– x TiO 3 3, 4, BNT‐Bi 0.5 K 0.5 TiO 3 5, 6, BNT‐KNbO 3 7, BNT‐BiAlO 3 8, (Bi,Na,K,Ag)TiO 3 ‐BaTiO 3 9, (Bi 0.5 Na 0.5 )TiO 3 ‐BaTiO 3 ‐(Bi 0.5 Na 0.5 )(Mn 1/3 Nb 2/3 )O 3 10, BNT‐Bi 0.5 K 0.5 TiO 3 ‐BaTiO 3 11, 12, BNT‐K 0.5 Na 0.5 NbO 3 13, (Bi 0.5 Na 0.5 )TiO 3 ‐Ba(Al 0.5 Nb 0.5 )O 3 14, Bi 0.5 Na 0.5 TiO 3 ‐Bi 0.5 K 0.5 TiO 3 ‐Bi 0.5 Li 0.5 TiO 3 15, Bi 0.5 Na 0.5 TiO 3 ‐BaTiO 3 ‐Bi 0.5 Li 0.5 TiO 3 16, (Bi 1/2 Na 1/2 )Ti 1– x (Zn 1/3 Nb 2/3 ) x O 3 17, (Bi 0.5 Na 0.5 ) 0.94 Ba 0.06 Zr y Ti 1– y O 3 18 and so on, have been developed by the introduction of ABO 3 ‐type compounds into BNT as well as the substitutions of analogous ions for the A‐site (Bi 0.5 Na 0.5 ) + or B‐site Ti 4+ ions. It can be noted that the formation of a new solid solution has been shown to be an effective method to improve the piezoelectric properties of the BNT ceramics 1, 2, 5–16. Generally, for Pb‐based materials, the multicomponent ceramics possess better piezoelectric properties than single or binary‐component ceramics.…”