scholarly journals Nucleation and Growth of Supported Metal Clusters at Defect Sites on Mgo and NaCl (001) Surfaces: The Cases of Pd and Ag

1999 ◽  
Vol 570 ◽  
Author(s):  
J. A. Venables ◽  
G. Haas ◽  
H. Brune ◽  
J.H. Harding
Keyword(s):  
Deposition Temperature ◽  
Metal Clusters ◽  
Variable Temperature ◽  
Nucleation And Growth ◽  
Force Microscopy ◽  
Atomic Force ◽  
Defect Sites ◽  
Wide Range ◽  
Adsorption Surface

ABSTRACTNucleation and growth of metal clusters at defect sites is discussed in terms of rate equation models, which are applied to the cases of Pd and Ag on MgO(001) and NaCl(001) surfaces. Pd/MgO has been studied experimentally by variable temperature atomic force microscopy (AFM). The island density of Pd on Ar-cleaved surfaces was determined in-situ by AFM for a wide range of deposition temperature and flux, and stays constant over a remarkably wide range of parameters; for a particular flux, this plateau extends from 200 K ≤ T ≤ 600 K, but at higher temperatures the density decreases. The range of energies for defect trapping, adsorption, surface diffusion and pair binding are deduced, and compared with earlier data for Ag on NaCl, and with recent calculations for these metals on both NaCl and MgO

scholarly journals Towards an Understanding of Crystallization by Attachment

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 463
Author(s):  
Haihua Pan ◽  
Ruikang Tang
Keyword(s):  
Capillary Condensation ◽  
Force Measurements ◽  
Force Microscopy ◽  
Physical Conditions ◽  
Driving Mechanisms ◽  
Atomic Force ◽  
Wide Range ◽  
Dynamics Simulations ◽  
Hydration Layers

Crystallization via particle attachment was used in a unified model for both classical and non-classical crystallization pathways, which have been widely observed in biomimetic mineralization and geological fields. However, much remains unknown about the detailed processes and driving mechanisms for the attachment. Here, we take calcite crystal as a model mineral to investigate the detailed attachment process using in situ Atomic Force Microscopy (AFM) force measurements and molecular dynamics simulations. The results show that hydration layers hinder the attachment; however, in supersaturated solutions, ionic bridges are formed between crystal gaps as a result of capillary condensation, which might enhance the aggregation of calcite crystals. These findings provide a more detailed understanding of the crystal attachment, which is of vital importance for a better understanding of mineral formation under biological and geological environments with a wide range of chemical and physical conditions.

scholarly journals Temperature Effects on the HOPG Intercalation Process

2019 ◽  
Vol 4 (1) ◽  
pp. 23 ◽  
Author(s):  
Gianlorenzo Bussetti ◽  
Rossella Yivlialin ◽  
Claudio Goletti ◽  
Maurizio Zani ◽  
Lamberto Duò
Keyword(s):  
Common Procedure ◽  
Force Microscopy ◽  
Carbon Dissolution ◽  
Atomic Force ◽  
Defect Sites ◽  
Graphite Intercalation ◽  
Increasing Temperature ◽  
Chemical Strategies

Graphite intercalation via chemical strategies is a common procedure to delaminate stratified crystals and obtain a suspension of graphene flakes. The intercalation mechanism at the molecular level is still under investigation in view of enhancing graphene production and reducing damage to the original pristine crystal. The latter, in particular, can undergo surface detriment due to both blister evolution and carbon dissolution. The role of the electrolyte temperature in this process has never been investigated. Here, by using an in-situ atomic force microscopy (AFM) apparatus, we explore surface morphology changes after the application of fast cyclic-voltammetries at 343 K, in view of de-coupling the crystal swelling phenomenon from the other electrochemical processes. We find that blisters do not evolve as a consequence of the increasing temperature, while the quality of the graphite surface becomes significantly worse, due to the formation of some adsorbates on possible defect sites of the electrode surface. Our results suggest that the chemical baths used in graphite delamination must be carefully monitored in temperature for avoiding undesired electrode detriment.

scholarly journals Solid-electrolyte interphase nucleation and growth on carbonaceous negative electrodes for Li-ion batteries visualized with in situ atomic force microscopy

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Sergey Yu. Luchkin ◽  
Svetlana A. Lipovskikh ◽  
Natalia S. Katorova ◽  
Aleksandra A. Savina ◽  
Artem M. Abakumov ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Solid Electrolyte ◽  
Solid Electrolyte Interphase ◽  
Nucleation And Growth ◽  
Li Ion Batteries ◽  
Force Microscopy ◽  
Electrode Potentials ◽  
Atomic Force ◽  
Li Ion

Abstract Li-ion battery performance and life cycle strongly depend on a passivation layer called solid-electrolyte interphase (SEI). Its structure and composition are studied in great details, while its formation process remains elusive due to difficulty of in situ measurements of battery electrodes. Here we provide a facile methodology for in situ atomic force microscopy (AFM) measurements of SEI formation on cross-sectioned composite battery electrodes allowing for direct observations of SEI formation on various types of carbonaceous negative electrode materials for Li-ion batteries. Using this approach, we observed SEI nucleation and growth on highly oriented pyrolytic graphite (HOPG), MesoCarbon MicroBeads (MCMB) graphite, and non-graphitizable amorphous carbon (hard carbon). Besides the details of the formation mechanism, the electrical and mechanical properties of the SEI layers were assessed. The comparative observations revealed that the electrode potentials for SEI formation differ depending on the nature of the electrode material, whereas the adhesion of SEI to the electrode surface clearly correlates with the surface roughness of the electrode. Finally, the same approach applied to a positive LiNi1/3Mn1/3Co1/3O2 electrode did not reveal any signature of cathodic SEI thus demonstrating fundamental differences in the stabilization mechanisms of the negative and positive electrodes in Li-ion batteries.

THERMODYNAMICS OF NUCLEATION AND GROWTH

2002 ◽  
Vol 09 (03n04) ◽  
pp. 1565-1593 ◽  
Author(s):  
RUUD M. TROMP ◽  
JAMES B. HANNON
Keyword(s):  
Growth Process ◽  
Equilibrium Concentration ◽  
Nucleation And Growth ◽  
Atomic Scale ◽  
Scanning Tunneling ◽  
Force Microscopy ◽  
Atomic Force ◽  
Wide Range ◽  
Insight Into ◽  
Flux Diffusion

Nucleation and growth are often discussed in terms of kinetics, i.e. the adsorption of atoms from the gas phase or a solution onto a surface, the diffusion of these atoms on that surface, and their attachment to a growing nucleus, island or layer. In recent years, scanning tunneling and atomic force microscopy studies have tremendously improved our understanding of such kinetic processes for a wide range of materials. At relatively low temperatures where diffusion is slow, and where typical deposition rates result in adatom concentrations that far exceed the equilibrium concentration of adatoms on the surface, growth is indeed controlled by irreversible atomic scale kinetics. But at higher temperatures this is not necessarily the case. Indeed, the equilibrium concentration of adatoms can be so high that it is only slightly increased by an external flux. Diffusion can be so fast that spatially separated regions on the surface interact on a time scale that is not slow relative to the growth process. In such cases reversible, collective phenomena are more important than individual atomic events, and thermodynamics is more important than kinetics. In this paper we examine a number of cases related to nucleation and growth on surfaces, where a deep and quantitative insight into the growth process can be obtained by detailed consideration of the thermodynamics involved. It is our hope that this paper will help to bring about a balanced understanding of these phenomena, where kinetics and thermodynamics are two poles on a continuum with an importance that depends on the particulars of each experiment.

Photoconductivity of Pentacene Thin Film Transistors

2001 ◽  
Vol 665 ◽  
Author(s):  
D. Knipp ◽  
D.K. Murti ◽  
B. Krusor ◽  
R. Apte ◽  
L. Jiang ◽  
...  
Keyword(s):  
Deposition Temperature ◽  
Dark Conductivity ◽  
X Ray Diffraction ◽  
Electron Hole ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Thermal Oxide ◽  
Wide Range ◽  
Large Enhancement

ABSTRACTA very large enhancement of the photoconductivity in pentacene transistors at negative gate voltages is observed. The enhancement is attributed to the separation of electron-hole pairs by the gate field and the consequent slow recombination. The ratio of photoconductivity to dark conductivity is approximately independent of mobility, for samples with a wide range of microstructure. The pentacene films were thermally deposited at different deposition rates and temperatures on silicon thermal oxide. The structure and the morphology of the films were studied by x-ray diffraction measurements and atomic force microscopy, and the influence of the deposition temperature on the morphology and structural properties is discussed. The size of the crystals is correlated with the crystalline bulk phase of the material, which increases with the deposition temperature and the film thickness. The mobility of the transistors increases with the size of the crystallites.

scholarly journals The effect of a copolymer inhibitor on baryte precipitation

2014 ◽  
Vol 78 (6) ◽  
pp. 1423-1430 ◽  
Author(s):  
Cristina Ruiz-Agudo ◽  
Christine V. Putnis ◽  
Andrew Putnis
Keyword(s):  
Oil Recovery ◽  
Nucleation And Growth ◽  
Inhibition Mechanism ◽  
Scale Inhibitor ◽  
Island Nucleation ◽  
Force Microscopy ◽  
Acid Copolymer ◽  
Atomic Force ◽  
Embryo Stage

In situ atomic force microscopy (AFM) experiments were used to study the effect of trace amounts of a commercial inhibitor on the (001) baryte surface during growth. The additive tested was a copolymer, used as a scale inhibitor in oil recovery (maleic acid/allyl sulfonic acid copolymer with phosphonate groups, partial sodium salt). The morphology of the growth was used to gain a better understanding of the inhibition mechanism. Without an inhibitor, barium sulfate growth occurred by 2D island nucleation and spreading. The addition of a small amount (0.1 ppm and 0.5 ppm) of copolymer inhibitor enhances 2D nucleation but blocks growth. Just 1 ppm of inhibitor blocks nucleation and growth by adsorption of a copolymer layer onto the baryte surface. Similarly in 3D studies, small amounts of inhibitor seem to act on growth and not on nucleation and larger amounts of copolymer act on both by adsorption of the copolymer to all baryte surfaces keeping the particles in their embryo stage.

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