Elastic distortion determining conduction in BiFeO 3 phase boundaries.

Autor: Holsgrove KM; School of Mathematics and Physics, Queen's University Belfast UK kholsgrove04@qub.ac.uk m.arredondo@qub.ac.uk., Duchamp M; Ernst-Ruska Centre for Microscopy Juelich Germany.; Nanyang Technological University Singapore., Moreno MS; Bariloche Atomic Centre San Carlos de Bariloche Argentina., Bernier N; Univ. Grenoble-Alpes, CEA, Leti France., Naden AB; School of Mathematics and Physics, Queen's University Belfast UK kholsgrove04@qub.ac.uk m.arredondo@qub.ac.uk.; University of St. Andrews UK., Guy JGM; School of Mathematics and Physics, Queen's University Belfast UK kholsgrove04@qub.ac.uk m.arredondo@qub.ac.uk., Browne N; School of Mathematics and Physics, Queen's University Belfast UK kholsgrove04@qub.ac.uk m.arredondo@qub.ac.uk., Gupta A; Center for Materials and Information Technology, University of Alabama USA., Gregg JM; School of Mathematics and Physics, Queen's University Belfast UK kholsgrove04@qub.ac.uk m.arredondo@qub.ac.uk., Kumar A; School of Mathematics and Physics, Queen's University Belfast UK kholsgrove04@qub.ac.uk m.arredondo@qub.ac.uk., Arredondo M; School of Mathematics and Physics, Queen's University Belfast UK kholsgrove04@qub.ac.uk m.arredondo@qub.ac.uk.
Jazyk: angličtina
Zdroj: RSC advances [RSC Adv] 2020 Jul 27; Vol. 10 (47), pp. 27954-27960. Date of Electronic Publication: 2020 Jul 27 (Print Publication: 2020).
DOI: 10.1039/d0ra04358c
Abstrakt: It is now well-established that boundaries separating tetragonal-like (T) and rhombohedral-like (R) phases in BiFeO 3 thin films can show enhanced electrical conductivity. However, the origin of this conductivity remains elusive. Here, we study mixed-phase BiFeO 3 thin films, where local populations of T and R can be readily altered using stress and electric fields. We observe that phase boundary electrical conductivity in regions which have undergone stress-writing is significantly greater than in the virgin microstructure. We use high-end electron microscopy techniques to identify key differences between the R-T boundaries present in stress-written and as-grown microstructures, to gain a better understanding of the mechanism responsible for electrical conduction. We find that point defects (and associated mixed valence states) are present in both electrically conducting and non-conducting regions; crucially, in both cases, the spatial distribution of defects is relatively homogeneous: there is no evidence of phase boundary defect aggregation. Atomic resolution imaging reveals that the only significant difference between non-conducting and conducting boundaries is the elastic distortion evident - detailed analysis of localised crystallography shows that the strain accommodation across the R-T boundaries is much more extensive in stress-written than in as-grown microstructures; this has a substantial effect on the straightening of local bonds within regions seen to electrically conduct. This work therefore offers distinct evidence that the elastic distortion is more important than point defect accumulation in determining the phase boundary conduction properties in mixed-phase BiFeO 3 .
Competing Interests: There are no conflicts to declare.
(This journal is © The Royal Society of Chemistry.)
Databáze: MEDLINE
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