Simultaneous Deposition of W(VI) Species and Ni(II) Ions on the γ-Alumina Surface:  Mechanistic Model

Spanos, N.

doi:10.1021/jp982341t

Cited by 6 publications

(3 citation statements)

References 56 publications

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“…A better insight at a molecular level may be obtained through the models proposed for the description of the structure of the electrical double layer (edl) at the HAP/water interface. The triple layer model has been proven to successfully describe interfacial phenomena at the oxide/water interface . The application of this model to the HAP/water interface suggested that the adsorbed negatively charged species of phospho- l -serine (HL 2- ) should be located either at the inner Helmholtz plane (IHP) or in the diffuse part at the double layer.…”

Section: Resultsmentioning

confidence: 99%

Model Studies of the Effect of Orthophospho-l-serine on Biological Mineralization

Spanos

Koutsoukos

2001

Langmuir

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The effect of phospho-l-serine in supersaturated solutions of calcium phosphate was investigated at plethostatic conditions. Phospho-l-serine inhibited the crystal growth of hydroxyapatite {Ca5OH(PO4)3, HAP} by blocking the crystal growth centers through adsorption. Complete inhibition was attained with a phospho-l-serine concentration of 4 × 10-4 M. Analysis of the kinetics and adsorption isotherm results showed a Langmuir-type adsorption. The amount of phospho-l-serine adsorbed on HAP decreased as pH increased from 7.4 to 10.4. The adsorbed species of phospho-l-serine, which in the pH range 7.4−10.4 are mainly the monoprotonated species (HL2-), are located in the inner Helmholtz plane (IHP) of the double layer at the HAP/electrolyte interface, interacting with the surface of HAP with both electrostatic and chemical interactions. The location of the negatively charged HL2- species at the IHP caused a shift of the ζ-potential to more negative values. Finally, a model was established for the adsorption of phospho-l-serine onto the HAP surface at pH 7.4, according to which an ion pair forms between the protonated amino group of one HL2- species and one negative site of the surface of HAP, i.e., the phosphate or hydroxyl group. Due to electrostatic repulsion, the negatively charged deprotonated carboxyl and phosphate groups of the adsorbed HL2- species are oriented in a manner ensuring the maximum possible distance from the negatively charged surface of HAP.

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Section: Resultsmentioning

confidence: 99%

Model Studies of the Effect of Orthophospho-l-serine on Biological Mineralization

Spanos

Koutsoukos

2001

Langmuir

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“…As proposed in the Introduction, the Pb 2+ stabilizer affects the plating rate ( R ) and phosphorus content (P%) in the deposition layer (Ni−P alloy) via the electronic effect. The electron effect means the fluctuation of electron flow density occurring in the S−G EDL − (Figure ), wherein the IHP is attached by anions (e.g., H 2 PO 2 - , H 2 PO 3 - , and SO 4 2- ) except water molecules and the OHP mainly by solvated cations (e.g., Ni 2+ , Na + , etc.). On the basis of this model, Ni 2+ ions pick up electrons and are converted to metal atoms within the EDL.…”

Section: Structural Relevancy For Electron Transfer In the Stern-grah...mentioning

confidence: 99%

Role of a Pb²⁺ Stabilizer in the Electroless Nickel Plating System: A Theoretical Exploration

2004

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The electroless nickel plating process involves multiple chemical reactions that interrelate mutually in intricate ways and take place almost simultaneously. This work attempts to provide a theoretical template for understanding this complicated system from the role of heavy metal stabilizers. Pb 2+ ion was selected for the study because it is the most effective species in this category. A theoretical expression of the nickel deposition rate is created by envisioning the Stern-Grahame electrical double layer presumably attached to the plating frontier (the inner Helmholtz plane) as a one-dimensional potential well and the electron transfer from the Fermi level of plating frontier to Ni 2+ ions at the outer Helmholtz plane as the quantum tunneling effect. The deposition of P atoms is assumed to go through the oxidative-addition of hypophosphite (H 2 PO 2 -) ions at Ni atoms on the plating frontier and on this basis its theoretical deposition rate is developed. Another adsorption state of H 2 PO 2on the surface Ni atoms is proposed to form by its two oxygen atoms, and the P(I) center supplies electrons to the plating frontier through these two oxygen bridges. Establishing the relationship between Pb 2+ -ion concentration and the Fermi level of the plating frontier (i.e., inside the solid Ni-P alloy deposition layer on the plating substrate) is an important step for deriving the nickel and element phosphorus deposition rates. The stabilizing effect of the lead ion is attributed to its participation as the neutral atom in the lattice of the Ni-P film at the plating frontier, which results in the ascension of Fermi energy. Thus, the oxidation of hypophosphite at the plating frontier is retarded, which in turn slows down the deposition of both Ni and P that needs electrons. The dependence of the deposition rates of Ni and P on concentrations of Pb 2+ ion was experimentally examined. It is found that the theoretical models predict well the experimental trends. The parameters designated in the theoretical model are determined through a self-consistent computation procedure.

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“…[17][18][19] It is a well-established fact that W cannot be deposited in a pure state from aqueous solutions; however, W element can be co-deposited with iron-group metals, resulting in the iron-group alloys. [20][21][22][23] This phenomenon is called "induced co-deposition". The deposition mechanism of induced co-deposition (such as Co-W) is illustrated as the following scheme:…”

Section: Introductionmentioning

confidence: 99%

Electroless Deposition of W‐doped Ag Dendrites from HF Solution

Chang

et al. 2008

Chin. J. Chem.

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A simple method was developed for the preparation of W-doped Ag dendrites by using electroless deposition from hydrofluoride solution. The samples characterized by XPS, XRD, SEM and TEM techniques, show that the growth of silver is leading and can not be changed essentially by tungstate ions in the Ag-W binary system. A doping mode of W element was proposed, i.e., the doping of W may occur during silver deposition through chemisorption-chemical bonding of oxygen atoms of tungstate dimer with silver. Cyclic voltammetry was employed to determine the chemical bonding energy between silver and oxygen.

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Simultaneous Deposition of W(VI) Species and Ni(II) Ions on the γ-Alumina Surface: Mechanistic Model

Cited by 6 publications

References 56 publications

Model Studies of the Effect of Orthophospho-l-serine on Biological Mineralization

Model Studies of the Effect of Orthophospho-l-serine on Biological Mineralization

Role of a Pb²⁺ Stabilizer in the Electroless Nickel Plating System: A Theoretical Exploration

Electroless Deposition of W‐doped Ag Dendrites from HF Solution

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Simultaneous Deposition of W(VI) Species and Ni(II) Ions on the γ-Alumina Surface: Mechanistic Model

Cited by 6 publications

References 56 publications

Model Studies of the Effect of Orthophospho-l-serine on Biological Mineralization

Model Studies of the Effect of Orthophospho-l-serine on Biological Mineralization

Role of a Pb2+ Stabilizer in the Electroless Nickel Plating System: A Theoretical Exploration

Electroless Deposition of W‐doped Ag Dendrites from HF Solution

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Role of a Pb²⁺ Stabilizer in the Electroless Nickel Plating System: A Theoretical Exploration