Nonstoichiometric [012] dislocation in strontium titanate
Nonstoichiometric [012] dislocation in strontium titanate
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钛酸锶中的非化学计量[012]位错
DOI：
10.1016/j.actamat.2017.06.017
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发表时间：
2017
期刊：
影响因子：
9.4
通讯作者：
K. Matsunaga
中科院分区：
文献类型：
--
作者：
Y. Furushima;Y. Arakawa;A. Nakamura;E. Tochigi;K. Matsunaga
位错是晶体材料中的一维晶格缺陷，其核心独特的原子组态会影响材料的功能性质。本文报道了钛酸锶(SrTiO_3)中具有非化学计量比核心结构的[012]位错。透射电子显微镜和扫描电子显微镜观察表明，(001)小角度倾斜晶界由两种位错组成。一种是[001]刃位错，它补偿了以前研究中发现的边界的倾斜角。另一种是[012]位错，既有刃型也有螺型成分。这种位错被认为是为了补偿边界的轻微扭曲角而形成的。有趣的是，[012]位错具有特定的核心结构，分解成三个部分位错：B=1/2[011]，[001]和1/2[011]。在解离形成的层错处，由于(001)Sr-O层的缺失，两个(001)Ti-O层在层错平面上相邻。此外，从部分位错之间的间隔距离估算出层错的能量为0.4J/m2。结果表明，[012]位错是由于低能非化学计量比层错结构的存在而形成的。
Dislocations are one-dimensional lattice defects in crystalline materials, and unique atomic configurations at their core can affect functional properties of materials. Here we report on a [012] dislocation having a nonstoichiometric core structure in strontium titanate (SrTiO3). TEM and STEM observations showed that a (001) low-angle tilt grain boundary consists of two types of dislocations. One is a [001] edge dislocation that compensates a tilt angle of the boundary as found in previous studies. The other is a [012] dislocation with both edge and screw component. This dislocation is considered to be formed to compensate a slight twist angle of the boundary. It is interesting that the [012] dislocations have a specific core structure with the dissociation into three partial dislocations ofb= 1/2 [011], [001] and 1/2 [011]. At stacking faults formed with the dissociation, two (001) Ti-O layers were located to be neighbors across the stacking fault plane due to missing of a (001) Sr-O layer. In addition, the energy of the stacking fault was estimated to be 0.4 J/m2from the separation distances between partial dislocations. It is suggested that the [012] dislocation is formed due to presence of the nonstoichiometric stacking fault structure with low energy.