Piezoelectric and ferroelectric properties of [Bi0.5(Na1−x−yKxLiy)0.5]TiO3 lead-free piezoelectric ceramics

Abstract

The piezoelectric and ferroelectric properties of [Bi0.5(Na1−x−yKxLiy)0.5]TiO3 (BNKLT-x∕y) lead-free piezoelectric ceramics were studied. The ceramics show excellent piezoelectric and ferroelectric properties, and the optimum properties measured are as follows: piezoelectric constant d33=231pC∕N, planar and thickness electromechanical coupling factors kP=41.0% and kt=50.5%, remanent polarization Pr=40.2μC∕cm2, and coercive field Ec=2.47kV∕mm, respectively. Polarization versus electric (P-E) hysteresis loops of the ceramics are well rectangle shaped, and the dependence of P-E loops on temperature reveals that the depolarization temperature Td of BNKLT-0.15∕0.075 ceramics, which simultaneously have good piezoelectric properties (d33=164pC∕N,kp=36.3%,kt=48.6%) and strong ferroelectricity (Pr=38.8μC∕cm2,Ec=3.73kV∕mm) at room temperature, is about 195 °C.

Perovskite Srx(Bi1−xNa0.97−xLi0.03)0.5TiO3 ceramics with polar nano regions for high power energy storage

“…And since SrTiO 3 is an incipient ferroelectric with a cubic perovskite structure at room temperature [28], Sr 2+ was introduced in the BNT perovskite structures to break the long-range order of the ferroelectrics to generate PNRs in the matrix, giving the path for relaxor behaviour to be revealed [29,30]. Li + was co-substituted because of its small radius (0.090 nm), which can lead to the distortion of the octahedral [TiO 6 ] in the lattice to enhance the P max value [31]. Field-induced reversible transitions are responsible for further increasing the energy density [32].…”

Synthesis and characterization of lead-free 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 ceramic

“…[2][3][4][5] In this regard, several lead-free systems have emerged out including (Na 0.5 K 0.5 )NbO 3 (NKN), ZnO, (Bi 0.5 Na 0.5 )TiO 3 (BNT), and BaTiO 3 (BT) based compositions. 2,[6][7][8][9][10] Although the piezoelectric coefficient values of NKN and BNT systems have been improved using site engineering, [11][12][13] sintering aid 14 or a new synthesis technique; 2 their main drawbacks include the presence of highly volatile elements like Bi, Na, and K. This results in poor densification that leads to degradation in the physical properties. Moreover, the hygroscopic nature of these systems further hinders their applications.…”

Effects of B-Site Donor and Acceptor Doping in Pb-Free (Bi0.5Na0.5)TiO3 Ceramics

“…Each material has its merits and demerits. In terms of the piezoelectric coefficient (d 33 ), which is a key property, NKN-based ceramics appear to be the better choice considering their d 33 of ~416 pC/N (Saito et al, 2004), which is high compared to the ~231 pC/N of BNT-based ceramics (Lin et al, 2006). However, NKN-based ceramics exhibit poor reproducibility because of hygroscopic problems.…”