Theoretical study of the adsorption of a CaF2 molecule at the (111) surface of CaF2 I. Equilibrium adsorption positions

Dabringhaus, H.; Wandelt, K.

doi:10.1016/s0039-6028(02)02488-3

Cited by 10 publications

(14 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Optimized ⟨110⟩-oriented steps either comprise down-sloping O–O units perpendicular to the edge direction (Figure a, left) or display a concave shape with the outermost atom row being an O-row in the topmost atomic plane (Figure a, center). Following the established notation for step edges on the iso-structural CaF 2 (111) surface, − we refer to the two step configurations as type I (positive descent) and type II (negative descent) in the following. While the positive descent of the type I edge corresponds to a (110) nanofacet, the type II descent resembles a (111) plane.…”

Section: Resultsmentioning

confidence: 99%

Formation of One-Dimensional Electronic States along the Step Edges of CeO₂(111)

et al. 2012

View full text Add to dashboard Cite

Scanning tunneling microscopy (STM) combined with density functional theory (DFT) are used to analyze the structural and electronic properties of step edges on the surface of CeO(2)(111) films grown on Ru(0001). Depending on the preparation conditions, 211 or 110-oriented steps develop on the surface, which results in the formation of ceria ad-islands with hexagonal or triangular shapes. STM conductance spectroscopy reveals pronounced differences in the electronic properties of the step edges, as reflected in different onset positions of the ceria conduction band. The band shifts are related to the development of distinct edge electronic states that split-off from the ceria conduction band, as shown with DFT calculations. The separation of the edge states from the main band is governed by the atom-coordination and local charge-distribution along the edge, the latter giving rise to the development of electrostatic dipoles. We expect that the observed edge morphologies determine not only the electronic properties but also the adsorption behavior of step edges on the CeO(2)(111) surface.

show abstract

Section: Resultsmentioning

confidence: 99%

Formation of One-Dimensional Electronic States along the Step Edges of CeO₂(111)

et al. 2012

View full text Add to dashboard Cite

show abstract

“…Fluorite-type crystals have been extensively investigated in the past [1][2][3][4][5][6][7][8] due to their broad technological relevance, including optical applications such as litho-excimer laser optics [9,10], beam deliveries, and zoom lenses, but also as a fluxing agent in the aluminum industry, as ceramic composites in fuel cell applications [11], and as an insulator within semiconductor multilayer structures [12]. Recently, CaF 2 nanoparticles have also attracted interest for medical applications, e.g., as markers in cancer therapy [13] and for potential use in dental care [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Surface reconstruction of fluorites in vacuum and aqueous environment

Fisicaro

Sicher

Amsler

et al. 2017

Phys. Rev. Materials

View full text Add to dashboard Cite

Surfaces and interfaces of bulk materials with liquids are of importance for a wide range of chemical processes.In this work, we systematically explore reconstructions on the (100) surface of calcium fluoride (CaF 2 ) and other fluorites (MF 2 ), M = {Sr,Cd,Ba} by sampling the configurational space with the minima hopping structure prediction method in conjunction with density functional theory calculations. We find a large variety of structures that are energetically very close to each other and are connected by very low barriers, resulting in a high mobility of the topmost surface anions. This high density of configurational states makes the CaF 2 (100) surface a very dynamic system. The majority of the surface reconstructions found in CaF 2 are also present in SrF 2 , CdF 2 , and BaF 2 . Furthermore, we investigate in detail the influence of these reconstructions on the crystal growth of CaF 2 in solvents by modeling the fluorite-water interface and its wetting properties. We perform a global structural search both by explicitly including water molecules and by employing a recently developed soft-sphere solvation model to simulate an implicit aqueous environment. The implicit approach correctly reproduces both our findings with the explicit-water model and the experimentally reported contact angles for the partial-hydrophobic (111) and hydrophilic (100) surfaces. Our simulations show that the high anion mobility and the low coordination of the (100) surface atoms strongly favors the adsorption of water molecules over the (111) surface. The aqueous environment makes terminations with low-coordination surface atoms more stable, promoting (100) growth instead of the (111).

show abstract

“…Here the step distance amounted to about 60 nm. Summarizing these different results, one comes to the conclusion that the step distances on the CaF 2 (111) surface at experimentally accessible conditions should lie in the range λ = 10-100 nm, corresponding to densities of step sites of The configuration of the kink at a 110 -I step was determined in [15]. The formation energy resulted as E k f = 0.47 eV.…”

Section: Thin Crystal Layermentioning

confidence: 98%

“…For CaF 2 (111) values of the adsorption energies of the fluorine adion, F − ad , at the different surface sites (terrace, step and kink) are not known until now. We have therefore performed corresponding calculations subsequently to calculations of adsorption energies of the CaF 2 molecule at these positions [15]. An important factor in such calculations is the consideration of additional relaxations of ions of the crystal due to interactions with the adsorbed ion.…”

Section: Determination Of Adsorption Positions and Energiesmentioning

confidence: 99%

“…This concerns, for example, bulk growth of large CaF 2 crystals for nano-lithography, see, e.g., [12], as well as the formation of thin epitaxial layers on semiconductors: above all, because of the low misfit on silicon [13,14]. Within our studies we have recently also carried out theoretical determinations of the adsorption energies of the CaF 2 molecule at different sites on the (111) surface of the CaF 2 crystal [15] as well as of diffusion pathways on the terrace [16]. CaF 2 is known to possess anti-Frenkel disorder [17], which means that fluorine ions are removed from their normal lattice positions into interstitial sites located in the vacant cubes of the cubic primitive fluorine sublattice, i.e.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Theory of the Frenkel–Debye boundary layer at the (111) surface of pure CaF₂

Dabringhaus

Бутман

2003

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

The present paper is concerned with a theoretical study of the properties of the Frenkel-Debye boundary layer at the (111) surface of pure (undoped) CaF 2 , a crystal with anti-Frenkel defects, i.e. with anion vacancies and interstitials. The study is based on theoretical determinations of the adsorption energies of the fluorine ion at the terrace, step and kink sites on the surface, which are, together with the assumption of experimental step distances and theoretical kink concentrations, necessary pre-requisites for a quantitative description of the surface charge compensating that of the space-charge region. The results show that, for realistic surface conditions, the surface and space charges, and with them the potential between surface and bulk, are reduced considerably compared with those for an unlimited number of accessible surface sites. Nevertheless, on approaching the surface a strong increase in the anion vacancy concentration against that of the bulk still exists, which should lead to an increased ion conductivity in near-surface regions and thin fluorite layers.

show abstract

Theoretical study of the adsorption of a CaF2 molecule at the (111) surface of CaF2 I. Equilibrium adsorption positions

Cited by 10 publications

References 35 publications

Formation of One-Dimensional Electronic States along the Step Edges of CeO₂(111)

Formation of One-Dimensional Electronic States along the Step Edges of CeO₂(111)

Surface reconstruction of fluorites in vacuum and aqueous environment

Theory of the Frenkel–Debye boundary layer at the (111) surface of pure CaF₂

Contact Info

Product

Resources

About

Theoretical study of the adsorption of a CaF2 molecule at the (111) surface of CaF2 I. Equilibrium adsorption positions

Cited by 10 publications

References 35 publications

Formation of One-Dimensional Electronic States along the Step Edges of CeO2(111)

Formation of One-Dimensional Electronic States along the Step Edges of CeO2(111)

Surface reconstruction of fluorites in vacuum and aqueous environment

Theory of the Frenkel–Debye boundary layer at the (111) surface of pure CaF2

Contact Info

Product

Resources

About

Formation of One-Dimensional Electronic States along the Step Edges of CeO₂(111)

Formation of One-Dimensional Electronic States along the Step Edges of CeO₂(111)

Theory of the Frenkel–Debye boundary layer at the (111) surface of pure CaF₂