X-ray photoelectron spectroscopy of amorphous and quasiamorphous phases of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="normal">Ba</mml:mi><mml:mi mathvariant="normal">Ti</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="normal">Sr</mml:mi><mml:mi mathvariant="normal">Ti</mml:mi><mml:m

Ehre, David; Cohen, Hagai; Lyahovitskaya, Vera; Lubomirsky, Igor

doi:10.1103/physrevb.77.184106

Cited by 91 publications

(58 citation statements)

References 31 publications

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“…[7,37] The data produced by these techniques are consistent with the view that the amorphous and quasi-amorphous films do not behave like solids containing random close-packed hard spheres, like ionic or metallic glasses. Rather, the amorphous and quasi-amorphous phases contain TiO 6 octahedra that are similar to the local bonding units (LBUs) in perovskite-like crystalline SrTiO 3 and BaTiO 3 .…”

Section: Progress Reportsupporting

confidence: 84%

“…Those oxygen ions that participate in apex sharing connections have two Ti 4þ neighbors as in a crystalline perovskite; those ions that participate in edge or face sharing of TiO 6 octahedra have more than two Ti 4þ neighbors, while the oxygen ions located at the unshared apices have only one Ti 4þ neighbor. Despite the difference in the coordination numbers, the XPS data [7,37] clearly show (Fig. 6) that the valence states of all oxygen ions are the same, which implies that there is a mechanism that equilibrates the charges on all oxygen ions and, thereby, stabilizes the network of TiO 6 LBUs.…”

Section: The Source Of Stability Of the Network Of The Local Bonding mentioning

confidence: 87%

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Quasi‐Amorphous Inorganic Thin Films: Non‐Crystalline Polar Phases

Wachtel

Lubomirsky

2010

Advanced Materials

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Quasi-amorphous thin films of BaTiO3, SrTiO3, and BaZrO3 are the only known examples of inorganic, non-crystalline, polar materials. The conditions under which they are formed and the origin of their polarity set these materials apart from other classes of inorganic materials. The most important feature of the quasi-amorphous phase is that the polarity is the result of the orientational ordering of local bonding units but without any detectable spatial periodicity. This mechanism is reminiscent of that observed in ferroelectric polymers and permits compounds that do not have polar crystalline polymorphs, such as SrTiO3 and BaZrO3, to form polar non-crystalline solids. In the present report, we provide an overview of the essential features of these materials including preparation, structure, and chemical composition. The report also reviews our current level of understanding and offers some guidelines for further development and application of non-crystalline inorganic polar materials.

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Section: Progress Reportsupporting

confidence: 84%

Section: The Source Of Stability Of the Network Of The Local Bonding mentioning

confidence: 87%

Quasi‐Amorphous Inorganic Thin Films: Non‐Crystalline Polar Phases

Wachtel

Lubomirsky

2010

Advanced Materials

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“…The Sr 3d spectrum peak positions (Sr3d 5/2 at 132 eV and Sr 3d 3/2 at 134 eV [27]) were quite similar among the prepared SrTiO 3 , Rh-SrTiO 3 , and the commercial SrTiO 3 . However, the spectrum shape of Rh-SrTiO 3 was different from those of both types of SrTiO 3 (Figure 3(a)).…”

Section: Figures 3(a)-3(d)mentioning

confidence: 67%

“…However, the spectrum shape of Rh-SrTiO 3 was different from those of both types of SrTiO 3 (Figure 3(a)). According to Ehre et al, the Sr 3d spectrum peak positions shift to higher energy region when SrTiO 3 becomes amorphous [27]. So, the Sr-O bonding in Rh-SrTiO 3 would be looser than that in SrTiO 3 .…”

Section: Figures 3(a)-3(d)mentioning

confidence: 99%

Enhanced Visible-Light-Sensitive Two-Step Overall Water-Splitting Based on Band Structure Controls of Titanium Dioxide and Strontium Titanate

Tanigawa¹,

Takashima²,

Irie³

2017

MSCE

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Visible light-induced two-step overall water-splitting was achieved by combining two types of photocatalysts, which were prepared by introducing foreign elements into rutile titanium dioxide (TiO 2 ) and strontium titanate (SrTiO 3 ) with a controlled electronic band structure. Rutile TiO 2 and SrTiO 3 were doped with chromium and tantalum (Cr,Ta-TiO 2 ) and with rhodium (Rh-SrTiO 3 ), respectively, to introduce visible-light sensitivity. Under irradiation with only visible light from a 420-nm LED lamp, the simultaneous liberation of hydrogen and oxygen with a molar ratio of ~2:1 was achieved with these two types of photocatalysts in the presence of iodate ion/iodide ion as a redox mediator.

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“…The broad feature appearing at ∼ 7.1 eV (marked C) is due to the bonding states of this hybridization while its non-bonding states appear at ∼ 5.2 eV (marked B). A discussion on these spectral features can be found in earlier reported experiments and band structure calculations on similar systems [8,21,22]. At 1486.60 eV photon energy, the emission features B and C are dominated by O 2p states due to their higher cross section compared to Ti 3d states [23].…”

Section: +mentioning

confidence: 99%

Chemical potential shift and gap-state formation in SrTiO3−δ revealed by photoemission spectroscopy

Pal

Kumar

Aswin

et al. 2014

Journal of Applied Physics

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In this study, we report on investigations of the electronic structure of SrTiO3 annealed at temperature ranging between 550 and 840• C in an ultrahigh vacuum. Annealing induced oxygen vacancies (Ovac) impart considerable changes in the electronic structure of SrTiO3. Using core-level photoemission spectroscopy, we have studied the chemical potential shift (∆µ) as a function of annealing temperature. The result shows that the chemical potential monotonously increases with electron doping in SrTiO 3−δ . The monotonous increase of the chemical potential rules out the existence of electronic phase separation in the sample. Using valence band photoemission, we have demonstrated the formation of a low density of states at the near Fermi level electronic spectrum of SrTiO 3−δ . The gap-states were observed by spectral weight transfer over a large energy scale of the stoichiometric band gap of SrTiO3 system leading finally to an insulator -metal transition. We have interpreted our results from the point of structural distortions induced by oxygen vacancies.

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X-ray photoelectron spectroscopy of amorphous and quasiamorphous phases ofBaTiO3andSrTi

Cited by 91 publications

References 31 publications

Quasi‐Amorphous Inorganic Thin Films: Non‐Crystalline Polar Phases

Quasi‐Amorphous Inorganic Thin Films: Non‐Crystalline Polar Phases

Enhanced Visible-Light-Sensitive Two-Step Overall Water-Splitting Based on Band Structure Controls of Titanium Dioxide and Strontium Titanate

Chemical potential shift and gap-state formation in SrTiO3−δ revealed by photoemission spectroscopy

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