Hiruma Yuji, Nagata Hajime, Takenaka Tadashi
Department of Electrical Engineering, Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba, Japan.
IEEE Trans Ultrason Ferroelectr Freq Control. 2007 Dec;54(12):2493-9. doi: 10.1109/TUFFC.2007.566.
The phase-transition temperatures and piezoelectric properties of x(Bi(1/2)Na(1/2))TiO3-y(Bi(1/2)Li(1/2))TiO3-z(Bi(1/2)K(1/2))TiO3 [x + y + z = 1] (abbreviated as BNLKT100(y)-100(z)) ceramics were investigated. These ceramics were prepared using a conventional ceramic fabrication process. The phase-transition temperatures such as depolarization temperatures T(d), rhombohedraltetragonal phase transition temperature T(R-T), and dielectric-maximum temperature T(m) were determined using electrical measurements such as dielectric and piezoelectric properties. The X-ray powder diffraction patterns of BNLKT100(y)-100(z)) show the morphotropic phase boundary (MPB) between rhombohedral and tetragonal at approximately z = 0.20, and the piezoelectric properties show the maximum at the MPB. The electromechanical coupling factor k(33), piezoelectric constant d(33) and T(d) of BNLKT4-20 and BNLKT8-20 were 0.603, 176 pC/N, and 171 degrees C, and 0.590, 190 pC/N, and 115 degrees C, respectively. In addition, the relationship between d33 and Td of tetragonal side and rhombohedral side for BNLKT4-100z and BNLKT8-100z were presented. Considering both high Td and high d(33), the tetragonal side of BNLKT4-100z is thought to be the superior composition. The d(33) and T(d) of BNLKT4-28 were 135 pC/N and 218 degrees C, respectively. Moreover, this study revealed that the variation of T(d) is related to the variation of lattice distortion such as rhombohedrality 90-alpha and tetragonality c/a.
研究了x(Bi(1/2)Na(1/2))TiO3 - y(Bi(1/2)Li(1/2))TiO3 - z(Bi(1/2)K(1/2))TiO3 [x + y + z = 1]（简称为BNLKT100(y)-100(z)）陶瓷的相变温度和压电性能。这些陶瓷采用传统陶瓷制备工艺制备。通过介电和压电性能等电学测量确定了去极化温度T(d)、菱方 - 四方相变温度T(R - T)和介电最大值温度T(m)等相变温度。BNLKT100(y)-100(z)的X射线粉末衍射图谱表明，在大约z = 0.20处存在菱方相和四方相之间的准同型相界（MPB），且压电性能在MPB处达到最大值。BNLKT4 - 20和BNLKT8 - 20的机电耦合系数k(33)、压电常数d(33)和T(d)分别为0.603、176 pC/N和171℃，以及0.590、190 pC/N和115℃。此外，还给出了BNLKT4 - 100z和BNLKT8 - 100z四方相侧和菱方相侧的d33与Td之间的关系。综合考虑高Td和高d(33)，认为BNLKT4 - 100z的四方相侧是更优的组成。BNLKT4 - 28的d(33)和T(d)分别为135 pC/N和218℃。此外，该研究表明T(d)的变化与晶格畸变如菱方度90 - α和四方度c/a的变化有关。
