Structures and chemistry of the annealed SrTiO3(001) surface

doi:10.1016/0039-6028(94)91378-1

Surface Science

Volume 310, Issues 1–3, 1 May 1994, Pages 128-134

https://doi.org/10.1016/0039-6028(94)91378-1 Get rights and content

Abstract

Surface structures and chemistry of the annealed SrTiO₃(001) have been studied by scanning tunneling microscopy and Auger electron spectroscopy. Our STM results show that islands arc formed on an originally smooth surface after annealing in ultra high vacuum at a temperature of 1300°C. Tunneling spectra show that the islands exhibit a different electronic structure than that of SrTiO₃, with an apparent bandgap of 6 eV rather than 3.2 eV. Auger electron spectroscopy indicates that annealing yields strontium enrichment at the surface. The nature of the islands and change of surface chemistry are discussed in terms of correlation of the STM and Auger results.

References (27)

W. Gopel
Prog. Surf. Sci.
(1985)
K. Nassau et al.
J. Cryst. Growth
(1988)
Y. Liang et al.
Surf. Sci.
(1993)
T. Matsumoto et al.
Surf. Sci.
(1992)
R. Courths et al.
Solid State Commun.
(1989)
B. Cord et al.
Surf. Sci.
(1985)
M. Tsukada et al.
Prog. Surf. Sci.
(1983)
R.M. Feenstra et al.
Surf. Sci.
(1987)
A.R. Protheroe et al.
Surf. Sci.
(1983)
N.B. Brooks et al.
Solid State Commun.
(1987)

V. Agrawel et al.

J. Vac. Sci. Technol. A

(1992)

Y. Liang and D.A. Bonnell, in: Atomic-Scale Imaging of Surface and Interface, Vol. 295, Eds. D.K. Biegelsen, D.J. Smith...

B. Reihl et al.

Phys. Rev. B

(1984)

Cited by (86)

Abnormal stability of hydrogenic defects and magnetism near the HSrCoO<inf>2.5</inf>(0 0 1) surface
2024, Applied Surface Science
For conventional semiconductors, defect usually occurs on the surfaces to satisfy electron counting model, relax stress, and induce reconstructions. However, it is highly complex for BM-SrCoO_2.5 (BM-SCO) and HSrCoO_2.5 (HSCO) thin films because of oxygen vacancy channels (OVCs) in the bulk that can be considered as internal surfaces in addition to the most stable (0 0 1) surface. Therefore, it is unclear which surface provides the most preferred sites for H related defects to form. In addition, these defects may play significant roles in the phase transformation and magnetism tuning in the ionic liquid gating. To answer this question, we investigated the stability of the surfaces, H vacancies, and interstitials in HSCO using density functional theory. Unlike the general stability of H related defects in conventional semiconductors, the H vacancy prefers sites near the external surface or OVCs, while the H interstitial prefers sites of oxygen on a layer that contains six-fold coordinated Co in bulk because of the significant energy penalty by surface-induced local distortions and the crystal field splitting of Co atoms, exhibiting a weak ferromagnetism. These findings enrich the general understanding of complex surface phenomena of defect formation and provide an explanation of the good reversibility during phase transformation.
Multifunctional strontium titanate perovskite-based composite photocatalysts for energy conversion and other applications
2023, International Journal of Hydrogen Energy
The detrimental impact of human activity on the global ecological situation has resulted in the active exploration and development of alternative energy sources. Efficient solar energy utilization can significantly contribute to resolving the current energy crisis, because approximately 1.36 kW m⁻² of solar radiation reaches the Earth's surface, and this can be used to satisfy the global energy requirements. Among various prevalent sunlight conversion technologies, photocatalytic materials are potentially useful for hydrogen production and other relevant applications. Existing technologies for the production and use of photocatalysts do not sufficiently address the target characteristics owing to the low solar conversion efficiency and service life in addition to high costs. However, recent advances in SrTiO₃-based heterostructures indicate that photocatalysts can potentially compete with modern solar energy technologies in terms of their practical application. In this review, we systematically consider the advancement in the production and application of SrTiO₃-based photocatalysts in various fields. The methods for obtaining complex heterostructures with different classes of nanomaterials are comprehensively discussed. The aim of this review is to highlight the advantages and limitations of using SrTiO₃-based photocatalytic systems. Finally, the future prospects of using SrTiO₃-based photocatalysts are considered from the perspective of their practical applications.
Ordered hybrid metamaterial of La<inf>0.7</inf>Sr<inf>0.3</inf>MnO<inf>3</inf>–Au vertically aligned nanocomposites achieved on templated SrTiO<inf>3</inf> substrate
2021, Materials Today Nano
Citation Excerpt :
The as-received STO substrate surface terminates with either SrO or TiOx terraces that are distributed randomly, as depicted in Fig. 1a [43]. Undergoing an annealing process allows a surface reconstruction, and was first observed based on regional Sr enrichment [44]. It was later proven to result from the alternative arrangement of TiOx and SrO strips [45], with the majority being TiOx strips, as demonstrated by the 3D schematic diagram shown in Fig. 1c and tomography image measured by atomic force microscopy in Fig. S1a.
Coupled multifunctionalities in nanocomposite thin films offer a pathway toward future integration of device applications. The oxide–metal two-phase nanocomposite thin films in a vertically aligned nanocomposite (VAN) morphology allow for unique structural control and functionality tuning toward future nanoscale devices. However, achieving in-plane ordering of the two phases remains challenging. In this work, we demonstrate an initial success of in-plane long-range ordering achieved in a new oxide–metal VAN system, La_0.7Sr_0.3MnO₃ (LSMO)–Au, through annealed SrTiO₃ (STO) substrates. The combination of plasmonic Au and ferromagnetic LSMO enables multifunctionalities, including magneto-optic coupling, hyperbolic dispersion, and tunable ferromagnetic anisotropy. Beyond this LSMO–Au VAN system demonstrated in this work, the long-range ordered two-phase structures induced by perovskite substrate surface terraces can be applied to other oxide–metal VAN systems.
Adsorption and reactivity of CO at a stepped SrTiO<inf>3</inf>(1 0 0) surface in the presence of Cu impurities
2020, Applied Surface Science
Citation Excerpt :
Perovskites are an interesting class of materials with relevant technological applications such as ferromagnets, semiconductors [1,2], insulators [3], solar cells and light adsorbing materials [4] and optoelectronics [5].
We have performed density functional calculations on a facetted SrTiO₃(1 1 0) surface, a model for stepped (1 0 0) surfaces considering both a pure and a Cu-doped system. The formation of oxygen vacancies and the adsorption of small have been studied in detail. Results show that Cu dopants strongly influence the reactivity of the step, both at the edge and at the facet sites, favoring the formation of oxygen vacancies. The adsorption of small molecules has been studied to obtain information about the role played by the system in catalytic processes. It is found that adsorption energies of NO, CO, CO₂ and O₂ at the vacancies of present in doped steps is always unfavored. The extraction of oxygen atom by direct CO adsorption on the oxidation mechanism has also been investigated for both pure unreduced and for reduced doped steps. In both cases, the desorption of CO₂ is an endothermic process, but the presence of the dopant significantly reduces the desorption energies.
Adsorption of CO and formation of carbonates at steps of pure and Co-doped SrTiO <inf>3</inf> surfaces by DFT calculations
2016, Applied Surface Science
Citation Excerpt :
This versatility is largely due to the wide range of possible stoichiometries, and is further increased by the possibility of doping with d- and f-block elements [1]. SrTiO3 is a prototypical perovskite with relevant photocatalytic properties which can be used as a substrate to grow oriented thin films of superconductors [2–4] and as insulator for tunneling devices [5]. Furthermore, SrTiO3 can be used to obtain ferromagnetic doped systems with in-plane magnetic anisotropy [6], high temperature oxygen sensors [7] or capacitors and in dielectrical components [8,9].
A reconstructed SrTiO₃ (1 1 0) surface, whose facets are oriented along the {1 0 0} planes, is used to study the reactivity of steps at the (1 0 0) surface. With this aim, we studied the interaction of CO on pure and Co-doped SrTiO₃ (1 1 0) facetted surfaces using density functional theory calculations. Results show that steps have peculiar properties: at variance to their terrace counterparts, step-edge O ions can absorb CO molecules. Furthermore, the interaction of CO with co-adsorbed O₂ easily gives rise to stable monodentate and bidentate carbonate species, which hamper the formation/desorption of CO₂. In this context, Co impurities play a double role: on one hand, they stabilize oxygen vacancies, on the other, they (partially) contrast the formation of carbonate species.
Comparative study of electronic, optoelectronic, optical, and thermodynamic properties of two ovalene molecules and their derivatives functionalized with potassium and chlorine atoms
2023, Polymer Bulletin

View all citing articles on Scopus

View full text

Structures and chemistry of the annealed SrTiO3(001) surface

Abstract

Prog. Surf. Sci.

J. Cryst. Growth

Surf. Sci.

Surf. Sci.

Solid State Commun.

Surf. Sci.

Prog. Surf. Sci.

Surf. Sci.

Surf. Sci.

Solid State Commun.

J. Vac. Sci. Technol. A

Phys. Rev. B

Structures and chemistry of the annealed SrTiO₃(001) surface