Subsurface reconstruction and saturation of surface bonds

Liu, Linhan; Sun, Yi-Zhi; Cheng, Zhiqiang; Zhu, Jing; Yu, Rong

doi:10.1016/j.scib.2018.10.001

Cited by 19 publications

(17 citation statements)

References 55 publications

(69 reference statements)

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“…Choosing negative spherical aberration of the objective lens and an appertaining overfocus, bright-atom contrast images are generated, which makes atomic columns appear bright on a dark background with a good signal-to-noise ratio, and both heavy and light elements can be accurately measured. − The (111) surface of Co 3 O 4 was directly imaged and quantitatively analyzed at the subangstrom scale with NCSI. The (111) surface of MgAl 2 O 4 was found to have subsurface reconstruction, while the topmost oxygen layer remained unchanged . The (100) and (110) surfaces of CeO 2 were also observed with an AC-TEM to study their metastable structures, oxygen adatoms, and vacancies. , For SnO 2 , the atomic termination of the (101) surface has also been determined directly using an AC-TEM …”

Section: Introductionmentioning

confidence: 99%

“…The (111) surface of MgAl 2 O 4 was found to have subsurface reconstruction, while the topmost oxygen layer remained unchanged. 25 The (100) and (110) surfaces of CeO 2 were also observed with an AC-TEM to study their metastable structures, oxygen adatoms, and vacancies. 26,27 For SnO 2 , the atomic termination of the (101) surface has also been determined directly using an AC-TEM.…”

Section: Introductionmentioning

confidence: 99%

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Atomic Structure and Properties of SnO₂ (100) and (101) Surfaces and (301) Steps in the (100) Surface

Liu

Cheng

et al. 2020

J. Phys. Chem. C

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The atomic and electronic structures of SnO2 surfaces are closely related to their catalysis and gas detection properties. In this study, the atomic structure of SnO2 (100) and (101) surfaces has been directly imaged by aberration-corrected transmission electron microscopy. Combined with density functional theory calculations and image simulations, we show that the (100) and (101) surfaces are terminated with Sn, with large outward relaxations. Bond valence analysis indicates that the surface stability can be attributed to the dual oxidation states (+4 and + 2) that are stable for Sn. For both surfaces, the oxidation state of Sn at the surface is reduced to +2 to compensate the surface polarity. The (301) facets that form steps at the (100) surface are also reduced, with SnO stoichiometry and + 2 oxidation state for Sn.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Atomic Structure and Properties of SnO₂ (100) and (101) Surfaces and (301) Steps in the (100) Surface

Liu

Cheng

et al. 2020

J. Phys. Chem. C

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“…Different from conventional surface-science techniques, aberration corrected transmission electron microscope (AC-TEM) can directly give the surface structures of semiconductors and insulators by surface profile imaging. This method does not require single crystals and has been successfully applied to many materials, such as MgAl 2 O 4 and Co 3 O 4 with the spinel structure, − SnO 2 and TiO 2 with the rutile structure. − In this work, the atomic structures and the stabilization mechanisms of the (101) and (001) surface of Mn 3 O 4 are studied by using the negative Cs imaging (NCSI) technique of AC-TEM, − combined with image simulations and density functional theory calculations. On the basis of the structure determination, the partition of the oxidation states of Mn is revealed and correlated to the catalytic activity of the surfaces.…”

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confidence: 99%

Surface Structures of Mn₃O₄ and the Partition of Oxidation States of Mn

Liu

Cheng

et al. 2021

J. Phys. Chem. Lett.

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The Mn(III) ions at Mn 3 O 4 surface are hypothesized to contribute to catalytic activity in oxygen reduction reaction. However, the surface structure and stability of Mn 3 O 4 are far less understood. Here, the atomic structures of the widespread ( 101) and (001) surfaces of Mn 3 O 4 are determined by combining aberration-corrected transmission electron microscopy and DFT calculations. The surface stabilization mechanisms and the oxidation states of Mn are revealed and correlated to the catalytic activity of the surfaces. The results show that the (101) surface undergoes a subsurface reconstruction, forming a rock-salt-type surface layer. The Mn(III) ions are in the outermost layer of the (001) surface but in the subsurface of the (101) surface. The surface partition of the Mn(III) ions provides a microscopic understanding to the observed higher catalytic activity of the (001) surface relative to the (101) surface and would contribute to further development of novel catalysts based on Mn 3 O 4 .

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“…A good match between experimental and simulated images would give accurate positions (usually several picometers) of the lattice sites. 29,32,37 Figure 2a shows typical aberration-corrected TEM images of the spinel (100) surface viewed in the [11̅ 0] direction. A TEM image of a larger area is given in the Supporting Information.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…This kind of "rigid" oxygen sublattice has also been observed in Fe 3 O 4 (001) 51 and MgAl 2 O 4 (111) surfaces. 37 Besides the determination of the cation positions on a surface, the occupancy of the sites is also important to stabilize a surface. It was shown, for the MgAl 2 O 4 (111) surface, that different occupancies may lead to large variation in surface free energy.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Flexible Cation Distribution for Stabilizing a Spinel Surface

et al. 2020

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The determination of the atomic structure of oxide surfaces has been a challenge because of their structural complexity. In this study, the coexistence of two types of reconstructions of the spinel (100) surface and their derivatives has been revealed by aberration-corrected transmission electron microscopy experiments and density functional theory calculations. Both reconstructions have the same oxygen sublattice as the bulk, but different cation distributions. The first type involves a full substitution of subsurface Mg atoms by Al. The second type involves a surface interstitial atom and a subsurface vacancy. The two types of surfaces avoid metallization and have significantly lower energies than the structural models known to date. The flexibility in cation distribution accounts for the sensitivity of the surface structure of spinel-type oxides on preparation routes, providing insights into the understanding and controlling of surface behavior and properties.

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Subsurface reconstruction and saturation of surface bonds

Cited by 19 publications

References 55 publications

Atomic Structure and Properties of SnO₂ (100) and (101) Surfaces and (301) Steps in the (100) Surface

Atomic Structure and Properties of SnO₂ (100) and (101) Surfaces and (301) Steps in the (100) Surface

Surface Structures of Mn₃O₄ and the Partition of Oxidation States of Mn

Flexible Cation Distribution for Stabilizing a Spinel Surface

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Subsurface reconstruction and saturation of surface bonds

Cited by 19 publications

References 55 publications

Atomic Structure and Properties of SnO2 (100) and (101) Surfaces and (301) Steps in the (100) Surface

Atomic Structure and Properties of SnO2 (100) and (101) Surfaces and (301) Steps in the (100) Surface

Surface Structures of Mn3O4 and the Partition of Oxidation States of Mn

Flexible Cation Distribution for Stabilizing a Spinel Surface

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Product

Resources

About

Atomic Structure and Properties of SnO₂ (100) and (101) Surfaces and (301) Steps in the (100) Surface

Atomic Structure and Properties of SnO₂ (100) and (101) Surfaces and (301) Steps in the (100) Surface

Surface Structures of Mn₃O₄ and the Partition of Oxidation States of Mn