Phase transition behavior and electrical properties of lead-free (Bi0.5K0.5)TiO3–LiNbO3 relaxor ferroelectric ceramics

Lead-free piezoelectric K0.5Bi0.5TiO3–Bi(Mg0.5Ti0.5)O3 ceramics with depolarisation temperatures up to ~220 °C

“…At room temperature, the planar coupling coefficient, kp, was 0.18 for x = 0.03 and 0.15 for x = 0.04, Table 2. These values of kp are comparable to a number of other KBT-based ceramics K0.5Bi0.5TiO3-Bi(Ni0.5Ti0.5)O3 (kp = 0.18, d33 = 126 pC/N) [21] and K0.5Bi0.5TiO3-LiNbO3 (kp = 0.18, d33 = 75 pC/N) [22], but lower than for Na0.5Bi0.5TiO3-BaTiO3 (kp ~ 0.21-0.36, d33 = 122-176 pC/N) [9] and Na0.5Bi0.5TiO3-K0.5Bi0.5TiO3 (kp ~ 0.27-0.35, d33 = 140-190 pC/N) [9,23]. …”

Dielectric and Piezoelectric Properties of Bi0.5K0.5TiO3-BaNb2O6 Lead-Free Piezoelectric Ceramics

“…Therefore, with addition of BN into KBT, the enhanced diffuse phase transition could be attributed to the coexistence of multiple ions at A-sites and B-sites, leading to a highly disordered crystal structure. Zuo et al 21 also reported similar results for (Bi 0.5 K 0.5 )-TiO 3 -LiNbO 3 ceramics. The diffuse phase transition and deviation from Curie-Weiss type may be assumed to be due to disorder.…”

“…This result is in accordance with the broadest dielectric peak for x = 0.01 and the narrowest one for x = 0.03 from the dielectric constant versus temperature curves of the (1 À x)KBT-xBN ceramics. In addition, Zuo et al 21 reported that the c values were 1.83 and 1.89 for pure KBT and 0.97KBT-0.03LiNbO 3 ceramic, respectively.…”

“…20 When a small amount of LiNbO 3 and Bi(Ni 0.5 Ti 0.5 )O 3 was added into KBT, a phase transformation from rhombohedral to tetragonal structure was induced. 21,22 Thus, it is expected that a phase structure change in KBT can be triggered by adding a small amount of BN. Meanwhile, it is hoped that BN can diffuse into KBT grains to enhance the dielectric and piezoelectric properties of KBT ceramics.…”

Enhanced dielectric and piezoelectric properties of Ta-doped 0.50(Na0.5Bi0.5)TiO3–0.50(K0.5Bi0.5)TiO3 lead-free ferroelectric ceramics

“…The binary system of (1À y) NBT-y KBT (hereafter BNKT) shows maximum electromechanical coupling in the compositional range of 0.16oyo0.20 called morphotropic phase boundaries (MPB) with rhombohedral and tetragonal crystal structures, respectively [13]. To enhance the dielectric and piezoelectric properties of BNKT system, various ionic substitution at A and B-site have been reported [14,15]. The purpose of the present study is to investigate the effect of n Ta-content on dielectric and electromechanical properties of BNKT (y=0.5) ceramic (BNKT50).…”