Yun Hwanhui, Prakash Abhinav, Birol Turan, Jalan Bharat, Mkhoyan K Andre
Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States.
Nano Lett. 2021 May 26;21(10):4357-4364. doi: 10.1021/acs.nanolett.1c00966. Epub 2021 May 11.
Distinct dopant behaviors inside and outside dislocation cores are identified by atomic-resolution electron microscopy in perovskite BaSnO with considerable consequences on local atomic and electronic structures. Driven by elastic strain, when A-site designated La dopants segregate near a dislocation core, the dopant atoms accumulate at the Ba sites in compressively strained regions. This triggers formation of Ba vacancies adjacent to the core atomic sites resulting in reconstruction of the core. Notwithstanding the presence of extremely large tensile strain fields, when La atoms segregate inside the dislocation core, they become B-site dopants, replacing Sn atoms and compensating the positive charge of the core oxygen vacancies. Electron energy-loss spectroscopy shows that the local electronic structure of these dislocations changes dramatically due to segregation of the dopants inside and around the core ranging from formation of strong La-O hybridized electronic states near the conduction band minimum to insulator-to-metal transition.
通过原子分辨率电子显微镜在钙钛矿BaSnO₃中识别出位错核心内外不同的掺杂行为，这对局部原子和电子结构有重大影响。在弹性应变的驱动下，当A位指定的La掺杂剂在位错核心附近偏析时，掺杂原子在压缩应变区域的Ba位点积累。这会触发与核心原子位点相邻的Ba空位的形成，从而导致核心的重构。尽管存在极大的拉伸应变场，但当La原子在位错核心内偏析时，它们会成为B位掺杂剂，取代Sn原子并补偿核心氧空位的正电荷。电子能量损失谱表明，由于掺杂剂在核心内外的偏析，这些位错的局部电子结构发生了巨大变化，范围从在导带最小值附近形成强La-O杂化电子态到绝缘体-金属转变。
