Simulation Analysis of Effect of Vacancies on Ferroic Domain Growth of BaTiO^3
Simulation Analysis of Effect of Vacancies on Ferroic Domain Growth of BaTiO^3
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DOI：
10.46300/9106.2021.15.197
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发表时间：
2022-01
影响因子：
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通讯作者：
T. Tsuzuki;S. Ogata;R. Kobayashi;Masayuki Uranagase;Seiya Shimoi;Saki Tsujimoto
中科院分区：
文献类型：
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作者：
T. Tsuzuki;S. Ogata;R. Kobayashi;Masayuki Uranagase;Seiya Shimoi;Saki Tsujimoto
钛酸钡是一种著名的铁电和压电材料，在各种器件中得到了广泛的应用。然而，铁电畴生长的微观机制还没有得到很好的理解。我们研究了点缺陷，单和双空位的Ba，Ti，和O，对BaTiO 3畴生长的影响，采用分子动力学模拟与核-壳原子间势。我们发现以下内容：（1）在垂直于外加电场方向的TiO平面上存在一种单空位VO1，它阻碍了外加电场引起的极化反转。由VO1产生的负电场根据总电场的局部强度来阻碍或辅助局部极化反转。(2)第一邻位双空位VBa-VO和VTi-VO与第二邻位双空位VBa-VO和VTi-VO相比，对畴生长的影响与外加电场不对称，使外加电场与极化关系呈现滞后行为。当所施加的电场和双空位偶极子的方向彼此相同时，即使在小电场下，畴也会生长。(3)沿外加电场方向的畴生长速度比沿垂直方向的畴生长速度高2个数量级。
BaTiO3 is one of the well-known ferroelectric and piezoelectric materials, which has been widely used in various devices. However, the microscopic mechanism of the ferroelectric domain growth is not understood well. We investigated the effects of point defects, mono- and di-vacancies of Ba, Ti, and O, on the domain growth of BaTiO3 using molecular dynamics simulation with the core-shell inter-atomic potential. We found the following: ｓ(1) One kind of monovacancy, VO1, located on the TiO plane perpendicular to the applied electric field direction, acts to hinder the polarization inversion induced by the applied electric field. The monopole electric field produced by VO1 either hinders or assists the local polarization inversion in accordance with the local intensity of the total electric field. (2) The 1st-neighbor divacancies VBa-VO and VTi-VO as compared to the 2nd-neighbor divacancies asymmetrically affect the domain growth with respect to the applied electric field, making the hysteresis behavior of applied electric field vs. polarization relation. The domain grows even at a small electric field when the directions of the applied electric field and the divacancy dipole are mutually the same. (3) The domain growth speed towards the applied electric field direction is about 2 orders of magnitude higher than that towards the perpendicular direction.