Mahmud Auinat

The Behavior of Zinc Metal in Alkaline Solution Containing Organic Inhibitors I. Electrochemical Studies of Zinc

The electrochemical behavior of zinc in strong alkaline solutions containing 8.5 M of potassium hydroxide (KOH) and polymeric organic inhibitors was evaluated. The concentrations of the organic inhibitors studies were in the range of 400-4000 ppm and included polyethylene glycol (PEG), with a molecular weight of 300-900, and polyoxyethylene alkyl phosphate ester acid form (GAFAC RA600). The electrochemical studies included potentiodynamic and potentiostatic polarizations. The inhibition properties of PEG 600, in the strong alkaline solution, are by far much more efficient than the inhibition capability of the other polymers. The studies also indicate that evaluation of the inhibitors should be conducted as a function of storage time. The evaluation of other polymeric compounds established that the polymer must contain a linear polyoxyethylene backbone with a chain length of ∼10 units with an optimal polymer concentration in the range of 800-2000 ppm. The described electrochemical methods are suggested as a rapid tool in the evaluation of organic polymers inhibitors, offering a precise determination of the optimal concentration in the alkaline media.

The Behavior of Zinc Metal in Alkaline Solution Containing Organic Inhibitors II. Identification of Surface Films Formed on Zinc

Surface analysis obtained with the use of high resolution scanning electron microscopy and in situ atomic force microscopy revealed different morphology characteristics developed at the zinc surface in the presence of polyoxyethylene backbone based organic inhibitors. Fourier transform Infrared spectroscopy data show that polyoxyethylene alkyl phosphate ester acid [GAFAC RA 600] adsorbed on the zinc surface via the phosphonium ion [R-PO 3 ] 2- head, while polyethylene glycol is adsorbed on the zinc surface via the alkoxide [R-CO] - anion head. It was also established that the preferred organic inhibitor should include a linear polyoxyethylene chain.

Origin of 5 V Electrochemical Activity Observed in Non-Redox Reactive Divalent Cation Doped LiM[sub 0.5−x]Mn[sub 1.5+x]O[sub 4] (0≤x≤0.5)Cathode Materials

Divalent cation doped lithiated Mn spinel with Zn and Mg as cathode materials for a lithium battery are investigated and partial reversible behavior is observed at the 5 V region. The electrochemical charge and discharge potential profiles of the Zn-doped materials indicate a close relationship between the lattice energy and lattice parameters in the Zn-doped spinel system. Lithium ions extracted from octahedral sites at the 5 V plateau during the charge cycle are partially reinserted back into the tetrahedral sites during the discharge step, which contributes to the partial reversible 5 V behavior. The significant findings reported here are that the strong tetrahedral site preference of divalent nonreactive cations such as Zn and Mg force Li cations onto octahedral sites in these materials, thus resulting in electroactivity at 5 V. In situ X-ray absorption spectroscopy measurements show that the Mn K edge is shifted to higher energy at the 4 V plateau during charge cycle and remains unchanged at the 5 V plateau. In situ Zn K-edge X-ray absorption near-edge structure measurements reveal that the valence state of zinc ions is unchanged at the 5 V plateau region. In situ Mn K-edge extended X-ray absorption fine structure studies suggest that O 2 - ions in the Zn-spinel lattice are partially oxidized to O - at the 5 V plateau during the anodic process and O - ions are reduced back to O 2 - during the cathodic process at the 5 V plateau. The oscillations of the lattice parameters observed at the 5 V plateau region during the anodic charge step are attributed to chemical instability of O - ions.

Origin of 5 V Electrochemical Activity Observed in Non-Redox Reactive Divalent Cation Doped LiM0.5 − x Mn1.5 + x O4 ( 0 ⩽ x ⩽ 0.5 ) Cathode Materials In Situ XRD and XANES Spectroscopy Studies

Divalent cation doped lithiated Mn spinel with Zn and Mg as cathode materials for a lithium battery are investigated and partial reversible behavior is observed at the 5 V region. The electrochemical charge and discharge potential profiles of the Zn-doped materials indicate a close relationship between the lattice energy and lattice parameters in the Zn-doped spinel system. Lithium ions extracted from octahedral sites at the 5 V plateau during the charge cycle are partially reinserted back into the tetrahedral sites during the discharge step, which contributes to the partial reversible 5 V behavior. The significant findings reported here are that the strong tetrahedral site preference of divalent nonreactive cations such as Zn and Mg force Li cations onto octahedral sites in these materials, thus resulting in electroactivity at 5 V. In situ X-ray absorption spectroscopy measurements show that the Mn K edge is shifted to higher energy at the 4 V plateau during charge cycle and remains unchanged at the 5 V plateau. In situ Zn K-edge X-ray absorption near-edge structure measurements reveal that the valence state of zinc ions is unchanged at the 5 V plateau region. In situ Mn K-edge extended X-ray absorption fine structure studies suggest that O 2 - ions in the Zn-spinel lattice are partially oxidized to O - at the 5 V plateau during the anodic process and O - ions are reduced back to O 2 - during the cathodic process at the 5 V plateau. The oscillations of the lattice parameters observed at the 5 V plateau region during the anodic charge step are attributed to chemical instability of O - ions.

Layered Boron-Nitrogen-Carbon-Oxygen Materials with Tunable Composition as Lithium-Ion Battery Anodes

The insertion of heteroatoms with different electronegativity into carbon materials can tune their chemical, electronic, and optical properties. However, in traditional solid-state synthesis, it is challenging to control the reactivity of monomers, and therefore, the amount and position of heteroatoms in the final materials. Herein, a simple, scalable, and general molten-state route to synthesize boron-nitrogen-carbon-oxygen (BNCO) materials with tunable boron-nitrogen-carbon composition, as well as electronic and optical properties, is reported. The new synthetic approach consists of polycyclic aromatic hydrocarbons (PAHs) and ammonia-borane as reactants that form a clear liquid-state stage spanning a wide temperature range, before the solid-state reaction. The molten-state stage enhances the control over the synthetic intermediates and final materials, owing to improved monomer miscibility and reactivity. The BNCO composition and optical properties are tuned by the PAH selection and final reaction temperature. The advantages of this method are demonstrated herein through the tunable optical properties, excellent stability to oxidization, facile deposition on substrates, and good activity as an anode material in lithium-ion batteries.

Copper Passivity in Carbonate Base Solutions and its Application in Chemical Mechanical Planarization (CMP)

Abstract Copper is fully passivated in sulfate solutions containing potassium carbonate. The potential range of copper passivity strongly depends on the relationship between sulfate and carbonate concentrations. At potentials above the passivity range copper suffers from localized attack by pitting corrosion. Copper passivity is more pronounced in solutions containing higher carbonate content. The increase in carbonate concentration shifts the breakdown potential towards positive anodic potentials while decreasing the anodic currents values in the region of passivity. In a solution containing carbonate copper passivity was detected in a wide potential range between OCP (~0.15 V SCE ) and ~1.0 V SCE . Increasing the sulfate concentration has the opposite effect on copper passivity than carbonate does.

Origin of 5 V Electrochemical Activity Observed in Non-Redox Reactive Divalent Cation Doped LiM0.5-xMn1.5+xO4 (0

Divalent cation doped lithiated Mn spinel with Zn and Mg as cathode materials for a lithium battery are investigated and partial reversible behavior is observed at the 5 V region. The electrochemical charge and discharge potential profiles of the Zn-doped materials indicate a close relationship between the lattice energy and lattice parameters in the Zn-doped spinel system. Lithium ions extracted from octahedral sites at the 5 V plateau during the charge cycle are partially reinserted back into the tetrahedral sites during the discharge step, which contributes to the partial reversible 5 V behavior. The significant findings reported here are that the strong tetrahedral site preference of divalent nonreactive cations such as Zn and Mg force Li cations onto octahedral sites in these materials, thus resulting in electroactivity at 5 V. In situ X-ray absorption spectroscopy measurements show that the Mn K edge is shifted to higher energy at the 4 V plateau during charge cycle and remains unchanged at the 5 V plateau. In situ Zn K-edge X-ray absorption near-edge structure measurements reveal that the valence state of zinc ions is unchanged at the 5 V plateau region. In situ Mn K-edge extended X-ray absorption fine structure studies suggest that O 2 - ions in the Zn-spinel lattice are partially oxidized to O - at the 5 V plateau during the anodic process and O - ions are reduced back to O 2 - during the cathodic process at the 5 V plateau. The oscillations of the lattice parameters observed at the 5 V plateau region during the anodic charge step are attributed to chemical instability of O - ions.