温度、电场及梯度系数对BaTiO₃双手性畴壁的影响

Effects of Temperature, Electric Field and Gradient Coefficient on the Bichiral Domain Walls of BaTiO₃

钛酸钡(BaTiO3, BTO)铁电材料的畴壁结构在挠曲电作用下呈现双手性结构,非传统的双手性畴壁结构对铁电材料的性能有较大影响。本文以笛卡尔坐标系为参考系,采用金兹堡-朗道-德希文理论模拟了不同温度、电场以及梯度系数对正方相钛酸钡180?双手性畴壁结构的影响。研究结果表明:当温度处于室温附近时,畴壁宽度会随着温度的升高而增加。施加正向电场会使铁电材料的极化曲线向上平移,增加正向极化值。施加负向电场,则增加负向极化值。当BTO无量纲梯度系数在0.6~2.1的范围内时,铁电畴壁的宽度会随着梯度系数的增大而增加。该结果将为双手性畴壁调控铁电材料性能提供可靠的依据。

The domain wall structure of barium titanate (BaTiO3) ferroelectric materials displays the bichiral structure under the flexoelectric effect, and the unconventional bichiral domain wall has a signifi-cant effect on the properties of ferroelectric materials. In this study, the effects of temperature, electric field and gradient coefficient on the bichiral domain wall of the tetragonal phase BaTiO3 are predicted in the Descartes coordinate system using Landau Ginsburg-Devonshire (LGD) theory. The results show that the wall width increases with the increase of temperature when the temperature is close to the room temperature. The positive electric field makes the polarization curve of the ferroelectric material move up, and increases the forward polarization value. When the negative electric field is applied, the negative polarization value increases. The domain wall width increases with the increase of the gradient coefficient of BaTiO3 when the dimensionless gradient coefficient is in the range of 0.6 - 2.1. The simulation results will provide a way to tune the properties of ferroelectric materials with the bichiral domain wall.