Probing dopant segregation in distinct cation sites at perovskite oxide polycrystal interfaces

Yoon, Hyein; Lee, Dong‐Kyu; Bae, Hyung Bin; Jo, Gi-Young; Chung, Hee‐Suk; Kim, Jin-Gyu; Kang, Suk–Joong L.; Chung, Sung‐Yoon

doi:10.1038/s41467-017-01134-x

Cited by 49 publications

(28 citation statements)

References 40 publications

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“…For fault observations, we prepared polycrystalline dense SrTiO 3 , BaCeO 3 , and LaCoO 3 sintered pellets, epitaxial LaNiO 3 thin films, and CsPbBr 3 nanocrystals (see the “Methods” section), all of which contain homologous stacking faults represented by two consecutive rocksalt [AX] layers (A = Sr, Ba, La, Cs; X = O, Br). Figure 1 shows a series of high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) 19 – 21 images at atomic resolution, verifying the presence of rocksalt [AX] faults in all five perovskite crystals (see Supplementary Fig. 1 for lower magnification images).…”

Section: Resultsmentioning

confidence: 77%

Local-electrostatics-induced oxygen octahedral distortion in perovskite oxides and insight into the structure of Ruddlesden–Popper phases

et al. 2021

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As the physical properties of ABX3 perovskite-based oxides strongly depend on the geometry of oxygen octahedra containing transition-metal cations, precise identification of the distortion, tilt, and rotation of the octahedra is an essential step toward understanding the structure–property correlation. Here we discover an important electrostatic origin responsible for remarkable Jahn–Teller-type tetragonal distortion of oxygen octahedra during atomic-level direct observation of two-dimensional [AX] interleaved shear faults in five different perovskite-type materials, SrTiO3, BaCeO3, LaCoO3, LaNiO3, and CsPbBr3. When the [AX] sublayer has a net charge, for example [LaO]+ in LaCoO3 and LaNiO3, substantial tetragonal elongation of oxygen octahedra at the fault plane is observed and this screens the strong repulsion between the consecutive [LaO]+ layers. Moreover, our findings on the distortion induced by local charge are identified to be a general structural feature in lanthanide-based An + 1BnX3n + 1-type Ruddlesden–Popper (RP) oxides with charged [LnO]+ (Ln = La, Pr, Nd, Eu, and Gd) sublayers, among more than 80 RP oxides and halides with high symmetry. The present study thus demonstrates that the local uneven electrostatics is a crucial factor significantly affecting the crystal structure of complex oxides.

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Section: Resultsmentioning

confidence: 77%

Local-electrostatics-induced oxygen octahedral distortion in perovskite oxides and insight into the structure of Ruddlesden–Popper phases

et al. 2021

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“…15 for a series of X-ray diffraction patterns of La(Ni 1−x Co x )O 3 (x = 0-1) films deposited on SrTiO 3 substrates). Atomic-scale EDS maps [48][49][50] in Fig. 5d specifically exemplify the homogeneous distribution of Ni and Co in a La (Ni 0.4 Co 0.6 )O 3 film, directly proving the solid-solution mixture.…”

Section: And 4 For Details)mentioning

confidence: 81%

Elucidating intrinsic contribution of d-orbital states to oxygen evolution electrocatalysis in oxides

et al. 2021

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Although numerous studies on oxide catalysts for an efficient oxygen evolution reaction have been carried out to compare their catalytic performance and suggest new compositions, two significant constraints have been overlooked. One is the difference in electronic conduction behavior between catalysts (metallic versus insulating) and the other is the strong crystallographic surface orientation dependence of the catalysis in a crystal. Consequently, unless a comprehensive comparison of the oxygen-evolution catalytic activity between samples is made on a crystallographically identical surface with sufficient electron conduction, misleading interpretations on the catalytic performance and mechanism may be unavoidable. To overcome these limitations, we utilize both metallic (001) LaNiO3 epitaxial thin films together with metal dopants and semiconducting (001) LaCoO3 epitaxial thin films supported with a conductive interlayer. We identify that Fe, Cr, and Al are beneficial to enhance the catalysis in LaNiO3 although their perovskite counterparts, LaFeO3, LaCrO3, and LaAlO3, with a large bandgap are inactive. Furthermore, semiconducting LaCoO3 is found to have more than one order higher activity than metallic LaNiO3, in contrast to previous reports. Showing the importance of facilitating electron conduction, our work highlights the impact of the near-Fermi-level d-orbital states on the oxygen-evolution catalysis performance in perovskite oxides.

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“…Dopant segregation at surfaces and grain boundaries in STO and other perovskites has been studied in the past, wherein dopants that have different charge states and ionic radii as compared to the host cations tend to segregate to grain boundaries and surfaces to reduce the total energy of the system. At semi‐coherent oxide heterointerfaces, in addition to the size and charge mismatch, an extra degree of complexity emerges in the form of misfit dislocations and the associated strain, which is typically longer ranged than for surfaces and high‐angle grain boundaries.…”

Section: Discussionmentioning

confidence: 99%

Influence of Chemistry and Misfit Dislocation Structure on Dopant Segregation at Complex Oxide Heterointerfaces

Dholabhai

Martínez

Uberuaga

2018

Advcd Theory and Sims

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Complex oxide heterostructures and thin films have emerged as promising candidates for diverse applications. Lattice mismatch between the two oxides lead to the formation of misfit dislocations, which influence vital material features. Trivalent dopant segregation to misfit dislocations at semi-coherent oxide heterointerfaces, while not well understood, is anticipated to impact interface-governed properties. Here, atomistic simulations elucidating the influence of misfit dislocations on dopant segregation at SrTiO 3 /MgO heterointerfaces are reported. SrO-and TiO 2 -terminated interfaces that have differing misfit dislocation structure were considered for trivalent dopants segregation. At SrO-terminated interface, dopants tend to segregate toward but not precisely to the heterointerface, whereas at TiO 2 -terminated interface, dopants exhibit a thermodynamic preference to accumulate at the heterointerface. Most favorable segregation sites at SrO-terminated interface are located within the coherent terrace, whereas those at TiO 2 -terminated interface are at misfit dislocation intersections. Atomic layer chemistry and the resulting misfit dislocation structure at the heterointerface, along with concomitant strain at the heterointerface due to mismatched dopants, play a critical role in influencing the observed trends for dopant segregation. Overall, the present results offer a fundamental atomic scale perspective of dopant behavior at semi-coherent complex oxide heterointerfaces and the interplay between dopant chemistry, interface chemistry, and misfit dislocation structure.

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Probing dopant segregation in distinct cation sites at perovskite oxide polycrystal interfaces

Cited by 49 publications

References 40 publications

Local-electrostatics-induced oxygen octahedral distortion in perovskite oxides and insight into the structure of Ruddlesden–Popper phases

Local-electrostatics-induced oxygen octahedral distortion in perovskite oxides and insight into the structure of Ruddlesden–Popper phases

Elucidating intrinsic contribution of d-orbital states to oxygen evolution electrocatalysis in oxides

Influence of Chemistry and Misfit Dislocation Structure on Dopant Segregation at Complex Oxide Heterointerfaces

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