Enhanced Temperature Stability of (1 − x)(K0.5Na0.5)0.94Li0.06NbO3-x(Bi0.5Na0.5)TiO3 Lead-Free Piezoelectric Ceramics

Abstract

1 À x)(K 0.5 Na 0.5 ) 0.94 Li 0.06 NbO 3 -x(Bi 0.5 Na 0.5 )TiO 3 (KNLN6-xBNT) lead-free piezoelectric ceramics with dense microstructures and good temperature stability were prepared by conventional sintering. The effects of the BNT on the structure, electrical properties, and temperature stability of the ceramics were studied. The results showed that BNT doping shifted the polymorphic phase transition below room temperature and significantly improved the temperature stability of KNLN6 ceramics. It was found that the KNLN6 ceramics doped with 3 mol.% BNT exhibited good temperature stability in the temperature range of 25°C to 180°C, as well as good electrical properties (d 33 = 152 pC/N, k p = 37.1%, Q m = 108, e r = 634, tand = 0.018 and T c = 415°C), suggesting that this material should be an attractive lead-free material for piezoelectric applications.

Enhanced thermal stability and fatigue resistance in MTiO3-modified (K0.5Na0.5)0.94Li0.06NbO3 lead-free piezoelectric ceramics

“…b The average grain size of KNLN6--E hysteresis loops of KNLN6-1MT ceramics measured at RT and 10 Hz weaken the ferroelectricity of the ceramics. Similar weakening effects have also been reported for MT (M = Ca, Sr, Ba, Mg, Bi 0.5 Na 0.5 , Bi 0.5 K 0.5 ) modified KNN-based ceramics[14,[16][17][18].…”

“…After a small amount of 1.0 mol% MT is added, the loops of the ceramics become much narrower, and both the P r and E c values decreases. The decrease in P r suggests that the addition of 1.0 mol% In our previous studies [14,16], we reported that a small amount of Bi 0.5 Na 0.5 TiO 3 or Bi 0.5 K 0.5 TiO 3 can greatly enhance the temperature stability of KNLN6 ceramics because of shifting of the PPT temperature down to below RT. In the present work, 1.0 mol% MT (Ca, Sr, Ba, Bi 0.5 Li 0.5 ) addition plays the same role in shifting of the PPT temperature for KNLN6 ceramics, so it is expected that the temperature stability of KNLN6 ceramics could be improved by MT doping.…”

“…By contrast, 1.0 mol% MT-modified samples have uniform grains with a relative small grain size, which is in the range of 2.5-5 lm. Figure 3b shows the average grain size of KNLN6-1MT (M = Ca, Sr, Ba, Bi 0.5 Na 0.5 , Bi 0.5 K 0.5 and Bi 0.5 Li 0.5 ) ceramics, it can be found that the average grain size of the ceramics decreases obviously as 1.0 mol% MT doped into KNLN6, implies that the role of 1.0 mol% MT in KNN-based system is a grain growth inhibiter [14][15][16]. Figure 4 shows the P-E hysteresis loops of KNLN6-1MT (M = Ca, Sr, Ba, Bi 0.5 Na 0.5 , Bi 0.5 K 0.5 and Bi 0.5 Li 0.5 ) ceramics measured at RT and 10 Hz.…”

“…In this work, the addition of 1.0 mol% MT in the ceramics decreases the T c and shifts the PPT below RT. It is reasonable to believe that the temperature stability of KNLN6-1MT ceramics could be improved due to the disappearance of PPT [7,14]. Figure 3a provides the micrographs of the KNLN6-1MT (M = Ca, Sr, Ba, Bi 0.5 Na 0.5 , Bi 0.5 K 0.5 and Bi 0.5 Li 0.5 ) ceramics microstructure observed on the surface of the compositions.…”

Microstructure, Phase Transition, and Electrical Properties of K x Na1−x NbO3 Lead-Free Piezoceramics

“…Therefore, lead-free piezoelectric ceramics have attracted much attention for protecting the environment and human health. [2][3][4][5][6][7] Among several lead-free candidates, (K,Na)NbO 3 (KNN)-based piezoceramics were well known and regarded as a promising alternative to PZT because of a breakthrough made by Saito et al; 8 i.e., a high d 33 value (416 pC/N) was achieved in the textured Li-, Ta-, and Sb-modified KNN system.…”