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Distinct dopant behaviors inside and outside dislocation cores are identified by atomic-resolution electron microscopy in perovskite BaSnO3 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.
Bibliographical noteFunding Information:
This work is supported primarily by the National Science Foundation (NSF) through the UMN MRSEC under Awards DMR-1420013 and DMR-2011401. This work utilized the UMN Characterization Facility, supported in part by the NSF through the UMN MRSEC program. The MBE growth work was supported primarily by the U.S. Department of Energy (DOE) through No. DE-SC0020211. A.P. acknowledges support from the University of Minnesota Doctoral Dissertation Fellowship.
- Core reconstruction
PubMed: MeSH publication types
- Journal Article
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Dopant segregation inside and outside dislocation cores in perovskite BaSnO 3 and reconstruction of the local atomic and electronic structures