Large electro-strain signal of the BNT–BT–KNN lead-free piezoelectric ceramics with CuO doping

Abstract

This paper investigates a system of 0.93[Formula: see text][Formula: see text]TiO3–0.06BaTiO3–0.01[Formula: see text][Formula: see text]NbO3–[Formula: see text]CuO (BNT–BT–KNN–[Formula: see text]CuO, [Formula: see text][Formula: see text]mol.%) ceramics, which were fabricated by the conventional solid-state process through the granulation of vacuum freeze drier. The results show that the CuO doping made a significant enhancement on the piezoelectric properties of the BNT–BT–KNN ceramics. With the doping of CuO, the transition temperature between ferroelectric phase and ergodic relaxor state is reduced to near room temperature, resulting in pinched [Formula: see text]–[Formula: see text] loops and “sprout” shape [Formula: see text]–[Formula: see text] curves. For the composition with [Formula: see text], a high unipolar strain of 0.39% under 5[Formula: see text]kV/mm contributes a large [Formula: see text][Formula: see text]pm/V at room temperature, which is competitive with the other BNT-based ceramics.

Dielectric and ferroelectric properties of CuO-doped lead magnesium niobate-based relaxor ferroelectric ceramics

“…This observation has also been reported in CuO-doped 0.93Bi 0:5 Na 0:5 TiO 3 -0.06BaTiO 3 -0.01K 0:5 Na 0:5 NbO 3 ceramics. 23 In addition, the tanδ in CuOdoped compositions shows relative increase compared to undoped counterparts due to formation of CuO precipitations at the grain boundaries. In order to depict the relative evolution of " r regarding the BZN content clearly, we plot the (" r À " 25 Þ=" 25 as a function of temperature at 1 kHz from À150 ○ C to 100 ○ C as shown in Fig.…”

“…18 In the literature, sintering additives are frequently adopted to lower the sintering temperature. According to the nature of the additives, there are two kinds of sintering additives, i.e., low melting point metal oxides (such as CuO) [19][20][21][22][23] and glass-phase additives. [24][25][26][27][28][29][30] Compared to the complex chemical compositions of glass additives, the effect of CuO for low-temperature sintering has been systematically studied in many ferroelectric systems.…”

“…Normally, the sintering temperature is decreased with increasing the CuO content and an optimal content around 1 at.% was suggested. [19][20][21][22][23] When the CuO content exceeded 1 at.%, the sintering temperature did not decrease further. In addition, excess CuO would lower the dielectric permittivity and related polarization.…”

Correlation between the structure and dielectric constant of Bi0.5(Na1‐xLix)0.5TiO3 (0 ≤ x ≤ 0.20) solid solutions

“…The main drawbacks of BNT for practical applications are its large coercive field and high electrical conductivity. Several studies have been reported in the literature on the modifications of the composition of BNT to overcome the drawbacks and to improve its piezoelectric properties 5–10 . Most of these studies are centered on the substitution of Na + by K + in Bi 0.5 (Na 1‐ x K x ) 0.5 TiO 3 , and these compositions are considered as potential candidates for various piezoelectric applications 11–23 .…”

Effect of Li Substitution on the Structure and Dielectric Constant of Bi0.5(Na⁠1-xLix)0.5TiO⁠3 (0 ≤ x ≤ 0.20) Solid Solution Series

“…The main drawbacks of BNT for practical applications are its large coercive eld and high electrical conductivity. Several studies have been reported in the literature on the modi cations of BNT to overcome these drawbacks and to improve its piezoelectric properties [5][6][7][8][9][10]. Most of these studies are centered on the substitution of Bi-or Na-site of the perovskite lattice by other metal ions of comparable size, ionic character, etc.…”