Effect of water adsorption on microscopic friction force on SrTiO3(001)

Iwahori, Keisuke; Watanabe, Shunji; Kawai, Maki; Kobayashi, Kei; Yamada, Hirofumi; Matsushige, Kazumi

doi:10.1063/1.1540223

Cited by 40 publications

(32 citation statements)

References 10 publications

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“…The data for these cells also compiled in Table II on the other hand demonstrates that the latter is a crucial point as the binding energy exhibits a strong coverage dependence, reflecting overall repulsive interactions consistent with the TPD data from Wang et al 3 . A value fairly representing the low-coverage limit is only reached in (2 × 2) cells, and as we will discuss in Section III.C below, it is this limit that is the appropriate one to discuss the Iwahori FFM experiments 6 .…”

Section: A Sro-terminationmentioning

confidence: 99%

“…(2), of the most stable water adsorption geometries at the different coverages at the SrO-termination (left) and TiO2-termination (right). In the top x-axis, the dependence on the water chemical potential is converted into pressure scales at 300 K and 500 K. The plain (blue) background boxes mark the region of gas-phase conditions probed by Iwahori et al in their FFM experiments 6 , while the dotted (gray) boxes indicate the region above the H2O-rich limit, i.e. where the present approach assuming equilibrium with water vapor is no longer strictly applicable.…”

Section: First-principles Thermodynamicsmentioning

confidence: 99%

“…Still, primarily due to the difficulties of preparing a perfect SrTiO 3 (001) surface that exhibits only one defect-free termination, a discomforting degree of uncertainty concerning the adsorption state, structure and energetics remains. A key experiment in this respect is therefore the Friction Force Microscopy (FFM) study by Iwahori et al, which exploits the FFM scanning capability to explore the adsorption of water separately on TiO 2 -and SrOterminated domains 6 . For a range of water exposures a change of the friction force was only measured above SrO-terminated domains and attributed to surface hydroxylation.…”

Section: Introductionmentioning

confidence: 99%

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Water adsorption and dissociation onSrTiO3(001)revisited: A density functional theory study

Guhl

Miller

2010

Phys. Rev. B

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We present a comprehensive density-functional theory study addressing the adsorption, dissociation and successive diffusion of water molecules on the two regular terminations of SrTiO3(001). Combining the obtained supercell-geometry converged energetics within a first-principles thermodynamics framework we are able to reproduce the experimentally observed hydroxilation of the SrO-termination already at lowest background humidity, whereas the TiO2-termination stays free of water molecules in the regime of low water partial pressures. This different behavior is traced back to the effortless formation of energetically very favorable hydroxyl-pairs on the prior termination. Contrary to the prevalent understanding our calculations indicate that at low coverages also the less water-affine TiO2-termination can readily decompose water, with the often described molecular state only stabilized towards higher coverages.

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Section: A Sro-terminationmentioning

confidence: 99%

Section: First-principles Thermodynamicsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Water adsorption and dissociation onSrTiO3(001)revisited: A density functional theory study

Guhl

Miller

2010

Phys. Rev. B

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“…42 Iwahori et al confirmed that the major contaminants on SrTiO 3 surfaces exposed to air are carbon species by detecting C 1s signals in XPS spectra. 43 We presume that both H 2 O and hydrocarbon adsorb on the TiO 2 layers, whereas mainly hydrocarbon occupies the SrO layers. Figures 4͑a͒ and 4͑b͒ show STM images taken of the 3°o ff vicinal surface of SrTiO 3 ͑Nb 0.5 wt % doped͒ annealed in UHV at different temperatures.…”

Section: Resultsmentioning

confidence: 90%

“…6͑c͒, which ruled this out. Another thing that possibly happens is that the water adsorbed reacted with the SrO layer 31,43 and changed its elastic properties. But, again this cannot explain the huge difference observed.…”

Section: Resultsmentioning

confidence: 99%

Contrast in friction and its inversion observed on metal deposited SrTiO3(100) surfaces

Shiraki

Nantoh

Wakatsuchi

et al. 2003

Journal of Applied Physics

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Articles you may be interested inTransition metal atoms pathways on rutile TiO2 (110) surface: Distribution of Ti3+ states and evidence of enhanced peripheral charge accumulation J. Chem. Phys. 138, 154711 (2013); 10.1063/1.4801025 Single crystal strontium titanate surface and bulk modifications due to vacuum annealing J. Appl. Phys. 110, 064107 (2011); 10.1063/1.3638692 Copper enhanced (111) texture in silver thin films on amorphous Si O 2 Growth and fractal scaling nature of copper thin films on TiN surface by metal organic chemical vapor deposition from hexafluoroacethylacetonate Cu (I) vinyltrimethylsilane J.Local variation of frictional properties associated with adatoms of Sr and Cu with SrTiO 3 (100) surfaces was investigated by friction force microscopy. On the surfaces partially covered with Sr, strong friction was observed on Sr adlayers. In contrast, the areas covered with Cu showed weaker friction than the substrates. We found that a thick Cu layer became easily worn by scanning, so the stepped surface of the substrate appeared in the scanned area. Furthermore, inversion of the contrast in friction between the SrO and TiO 2 terraces was observed in the same region during measurement. The origins of this friction behavior will be discussed in terms of the interaction between adsorbates and the substrate.

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Reaction Mechanism and Structure-Reactivity Relationships in the Stereospecific 1,4-Polymerization of Butadiene Catalyzed by Neutral Dimeric Allylnickel(II) Halides [Ni(C3H5)X]2 (X−=Cl−, Br−, I−): A Comprehensive Density Functional Theory Study

Tobisch

Taube

2001

Chem. Eur. J.

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For the first time, a comprehensive and consistent picture of the catalytic cycle of 1,4-polymerization of butadiene with neutral dimeric allylnickel(II) halides [Ni(C3H5)X]2 (X = Cl- (I), Br- (II), and I- (III)) as single-site catalysts has been derived by means of quantum chemical calculations that employ a gradient-corrected density-functional method. All crucial reaction steps of the entire catalytic course have been scrutinized, taking into account butadiene pi complex formation, symmetrical and asymmetrical splitting of dimeric pi complexes, cis-butadiene insertion, and anti-syn isomerization. The present investigation examines, in terms of located structures, energies and activation barriers, the participation of postulated intermediates, in particular it aimed to clarify whether monomeric or dimeric species are the catalytically active species. Prior qualitative mechanistic assumptions are substituted by the presented theoretically well-founded and detailed analysis of both the thermodynamic and the kinetic aspects, that substantially improve the insight into the reaction course and enlarge them with novel mechanistic proposals. From a mechanistic point of view, all three catalysts exhibit common characteristics. First, chain propagation occurs by cis-butadiene insertion into the pi-butenylnickel(II) bond with nearly identical intrinsic free-energy activation barriers. Second, the reactivity of syn-butenyl forms is distinctly higher than that of anti forms. Third, the chain-propagation step is rate-determining in the entire polymerization process, and the pre-established anti-syn equilibrium can always be regarded as attained. Accordingly, neutral dimeric allylnickel(II) halides catalyze the formation of a stereo-regular trans-1,4-polymer under kinetic control following the k1t channel with butenyl(halide)(butadiene)NiII complexes being the catalytically active species. Production of a stereoregular cis-1,4-polymer with allylnickel chloride can only be explained by making the k2c channel accessible by the formation of polybutadienyl(butadiene) complexes, which is accompanied by the coordination of the next double bond in the growing chain to the NiII center.

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Effect of water adsorption on microscopic friction force on SrTiO3(001)

Cited by 40 publications

References 10 publications

Water adsorption and dissociation onSrTiO3(001)revisited: A density functional theory study

Water adsorption and dissociation onSrTiO3(001)revisited: A density functional theory study

Contrast in friction and its inversion observed on metal deposited SrTiO3(100) surfaces

Reaction Mechanism and Structure-Reactivity Relationships in the Stereospecific 1,4-Polymerization of Butadiene Catalyzed by Neutral Dimeric Allylnickel(II) Halides [Ni(C3H5)X]2 (X−=Cl−, Br−, I−): A Comprehensive Density Functional Theory Study

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