Effects of quenching on bending strength and piezoelectric properties of (Bi_0.5Na_0.5)TiO₃ceramics

Abstract

Lead-free piezoelectric bismuth sodium titanate (Bi 0.5 Na 0.5)TiO 3 (BNT) ceramics were prepared by quenching and the correlation among a depolarization temperature T d , the mechanical strength, and their piezoelectric properties were investigated. We controlled the quenching rate in the temperature range from 1100°C to 800°C. We examined the 5 patterns of the quenching rate (QR): 0.05 (ordinary firing, OF), 3.85, 5.77, 6.67, and 15.0 (quenching) o C/s. T d of the rapid quenched sample reached 229°C (QR = 15.0), but its mechanical strength decreased to a quarter of that of the OF ceramics. On the other hand, T d was 211°C at QR = 3.85 which was higher than that of OF-ceramic (QR = 0.05) at about 180°C. Moreover, three-point bending strength (227 MPa) of the quenched BNLT4 (QR = 3.85) was equivalent to that of the OF ceramics (235 MPa). Therefore, both T d and the mechanical strength were improved by controlling the quenching rate.

Thermal depolarization and electromechanical hardening in Zn2+‐doped Na1/2Bi1/2TiO3‐BaTiO3

“…Quenching results in a similar increase in T F-R in NBT6BT (28), while for NBT9BT, the depolarization temperature was increased to 200 o C (29). A drawback of the quenching approach is the development of residual stress in samples, which in extreme cases can result in fracture and limit this strategy in real-time applications (19,30). None of the chemical modifications have resulted in significant increase in both T F-R and Q m (20)(21)(22)(23)(24)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40).…”

Deformation and bending strength of high‐performance lead‐free piezoceramics

“…While this has been considered in a recent detailed evaluation of the fracture toughness in NBT‐BT‐based 6 and KNN‐based 8 lead‐free piezoceramics, the detailed discussion on the effect of non‐linearity of lead‐free piezoceramics on their fracture strength is still lacking 17 . Furthermore, PZT, NBT‐BT, and KNN variants exhibit both low fracture strength 15,17 as well as low fracture toughness 8,9 (Table 1).…”

Studies of structural and electrical characteristics of multi-substituted Bi0.5Na0.5TiO3 ferroelectric ceramics

“…Hence, the development of lead-free ferroelectric ceramics is required urgently and has always become a popular topic in this research field also draws the attention of researchers [7,8]. Among various lead-free materials, bismuth sodium titanate (Bi0.5Na0.5) TiO3 (commonly known as BNT) is considered as one of the most favorable ferroelectric ceramics having perovskite-structure with rhombohedral (R3c) symmetry at room temperature [9,10]. Since the first discovery of BNT4 in1960s by Smolenskii et al [11].…”