Electronic and atomic structures of edge and screw dislocations in rock salt structured ionic crystals
Electronic and atomic structures of edge and screw dislocations in rock salt structured ionic crystals
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DOI：
10.1080/14786435.2018.1478146
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发表时间：
2018-06
影响因子：
1.6
通讯作者：
M. Ukita;A. Nakamura;T. Yokoi;K. Matsunaga
中科院分区：
文献类型：
--
作者：
M. Ukita;A. Nakamura;T. Yokoi;K. Matsunaga
摘要采用第一性原理方法研究了氯化钠和氯化银中刃位错和螺位错的电子结构和原子结构。1/2刃位错和1/2螺位错是由于这些晶体的最容易的滑移系统，在第一原理的方式进行了处理。结果表明，在NaCl和AgCl中，刃型位错在多个原子平面上都具有扩展的核心结构。相反，螺旋位错在氯化银显示出不同的剪切应变周围的位错核心，在氯化钠，虽然有一个类似的原子结构在两个晶体。局部电子结构周围的位错核心在氯化银表现出更大的原子轨道之间的成键相互作用比那些在氯化钠，表明共价相互作用是更显着的位错核心氯化银。从过剩位错能的角度，发现AgCl中的位错比NaCl中的位错稳定得多。特别是，螺旋位错的AgCl的有更小的核心能量比刃型位错。这表明，螺旋位错可以很容易地形成和繁殖的氯化银，这可能是密切相关的观察到的延展性氯化银。
ABSTRACT First-principles calculations were performed to investigate electronic and atomic structures of edge and screw dislocations in NaCl and AgCl. 1/2 edge and 1/2 screw dislocations, which are the ones due to the easiest slip system of these crystals, were treated in a first-principles manner. It was found that the edge dislocation has extended core structures over several atomic planes in both NaCl and AgCl. In contrast, the screw dislocation in AgCl showed the different shear strain around the dislocation core from that in NaCl although the one has a similar atomic structure in the two crystals. Local electronic structures around the dislocation cores in AgCl exhibit larger bonding interactions between atomic orbitals than those in NaCl, indicating that covalent interactions are more significant at the dislocation cores of AgCl. From excess dislocation energies, it was found that the dislocations in AgCl are much more stable than those in NaCl. Especially, the screw dislocation of AgCl has much smaller core energy than that of the edge dislocations. This suggests that the screw dislocations can be easily formed and multiplied in AgCl, which may be closely related to the observed ductility of AgCl.