Temperature dependence of dielectric properties and phase transition behavior in quenched (Bi_0.5Na_0.5)TiO₃ceramics

Abstract

Lead-free piezoelectric (Bi 0.5 Na 0.5 )TiO 3 (BNT) ceramics, which exhibit a Bi-based A-site complex perovskite structure with rhombohedral symmetry, were prepared by controlling: the quenching temperature and the quenching rate (QR). We examined the relationship between structural order and quenching effect of the structural phase transition behavior, which was obtained from the dielectric properties. Additionally, the electrical properties were evaluated. These measurements showed that the depolarization temperature (T d ) increased by approximately 50 °C during these two control processes. Furthermore, the full width at half maximum (FWHM) for temperature dependence of tan δ decreased with increasing quenching temperature and QR. In conclusion, the increase in T d is strongly correlated with the decrease in FWHM, which suggests a more ordered arrangement of cations, Bi 3+ and Na + , in the Bi-based A-site complex perovskite structure. Moreover, the quenching effect does not deteriorate the piezoelectric properties.

Oxygen tracer diffusion analysis and observation of domain structure in quenched (Bi0.5Na0.5)TiO3ceramics

“…Moreover, in the effective temperature range above 800 °C, 23) the quenching rate (cooling speed) was set to four values: 0.003, 0.05 (ordinary firing), 3.85, and 15.0 °C s −1 , controlled based on previous reports. 28,30) The samples were columnar, approximately 15 mm in diameter and 10 mm in height. The lattice constants and lattice distortion 90-α were observed by X-ray diffraction (XRD) from 25 °C to 250 °C using Cu Kɑ radiation (Rigaku RINT-2000, 40 kV, 40 mA).…”

“…23) The increase in T d for BNT solid solution systems is associated with an increase in lattice distortion due to quenching effects on a rhombohedral phase (90-α). [23][24][25][26][27][28][29][30][31] This quenching effect is observed not only in a rhombohedral structure but also in a tetragonal structure. T d and lattice distortion (c/a) were strongly correlated in the tetragonal structure.…”

“…On the other hand, in our previous report, we pointed out that quenched BNT ceramics show a sharper phase transition than ordinary fired (OF-) BNT in terms of the temperature dependence of the dielectric constant and tan δ. 28) This indicates that the structure of quenched BNT ceramics is more ordered than that of OF-BNT ceramics. Regarding the origin of this ordered structure, in Pb(Sc 0.5 Ta 0.5 )O 3 (PST) with B-site complex perovskite structures, the cations of the complex sites are arranged in order.…”

Local structure analysis of Bi0.5Na0.5TiO3–BaTiO3 solid solutions

“…Bismuth sodium titanate Bi 0.5 Na 0.5 TiO 3 (BNT) is a lead-free piezoelectric material that exhibits relatively good piezoelectric properties. [1][2][3][4][5][6][7][8][9] BNT has also been developed as a stable battery electrode and energy storage materials suitable for working over a wide temperature ranges. 10,11) Accordingly, the methods for synthesizing high-quality BNT samples have been developed.…”

Effect of strontium substitution on growth and piezoelectric properties of calcium magnesium silicate Ca2MgSi2O7 single crystals

“…Polar piezoelectric materials generally have a high dielectric constant and high piezoelectric constant d ij ; hence, they have been used in medical transducer and actuator devices. [2][3][4][5][6] On the other hand, nonpolar piezoelectric materials show a low dielectric constant and low d ij , but have higher phase transition temperatures. Therefore, their possible applications include gas sensors, 7) microbalance, 8) and combustion pressure sensors, 9) which operate at temperatures higher than 300 °C.…”