Composition-property relationships in high-κ LaxZr1-xOy thin films from aqueous solution

Miniaturization of microelectronic devices has reached a fundamental scaling limit; parasitic electron tunneling through the ultrathin gate dielectric has become a major obstacle to continued device performance. One method for overcoming this limitation is to replace SiO₂ gate dielectrics with thicker high-κ metal oxides. La₂O₃ and ZrO₂ are two such materials that have received significant interest, but low stability to post-anneal water absorption and low-crystallization temperatures, respectively, have limited their widespread use. We recently reported an aqueous, all-inorganic route to high-κ lanthanum zirconium oxide dielectric films (1/1 La/Zr), which mitigates the disadvantages of the binary oxides but maintains their high-κ properties. In this contribution, we vary the La/Zr ratio of the aqueous precursor to optimize the properties of the resulting films. We find that the La_0.20Zr_0.80O_y composition is optimal for providing a high dielectric constant (∼18.2 at 600 °C) while maintaining excellent film morphology and stability. 20% La was necessary to prevent crystallization up to 600 °C, but films with higher La content displayed diminished dielectric constants and decreased stability towards post-anneal water absorption.     

Electrodeposition of hyaluronic acid and hyaluronic acid–bovine serum albumin films from aqueous solutions

Hyaluronic acid (HYH) films were prepared from aqueous sodium hyaluronate (HYNa) solutions by anodic electrodeposition. The film thickness was varied in the range of 0–20 μm by the variation of the deposition time and HYNa concentration. The deposition rate was low at HYNa concentration below 1 g L⁻¹ and increased significantly in the range of 3–5 g L⁻¹. The addition of bovine serum albumin (BSA) to the HYNa solutions resulted in increased deposition yield, which was attributed to the formation of composite HYH–BSA films. The thickness of the HYH–BSA films deposited by anodic electrodeposition was varied in the range of 0–80 μm. The HYH and composite HYH–BSA films were studied by scanning electron microscopy, thermogravimetric analysis, differential thermal analysis, Fourier transform infrared spectroscopy and circular dichroism spectroscopy. The deposition mechanism and kinetics of deposition are discussed.     

Electrodeposition of iron–molybdenum–tungsten coatings from citrate electrolytes

Specific features of the electrodeposition of iron–molybdenum–tungsten coatings from citrate electrolytes based on iron(III) sulfate in the dc mode and with a unipolar pulsed current were studied. It was shown that varying the relative concentrations of salts of alloy-forming metals and the solution pH makes it possible to obtain lustrous compact coatings with low porosity and various contents of high-melting components. The effect of temperature on the coating composition and current efficiency was examined. The current density ranges providing high electrolysis efficiency were found and it was demonstrated that using a pulsed current favors formation of more compositionally homogeneous surface layers at a smaller amount of adsorbed nonmetallic impurities in the coatings. The iron–molybdenum–tungsten coatings are X-ray-amorphous and have better physicomechanical properties and corrosion resistance as compared with the base, which makes it possible to recommend these coatings for application in techniques for surface reinforcement and restoration of worn-out articles.     

Formation of hybrid nano-crystals in organic–inorganic films from a basic sol

Organic–inorganic films containing hybrid nanocrystals have been prepared by sol–gel processing in controlled conditions. We have systematically changed the temperature and the aging time of a precursor sol containing an organically modified alkoxide bearing an epoxy group, 3-glycidoxypropyltrimethoxysilane, to obtain a controlled crystallization of hybrid layered structures in hybrid films. The precursor sol has been aged at different temperatures, from 5 to 60 °C, and for 1, 2 or 3 days; the films have been deposited from the aged sol and immediately after characterized by X-ray diffraction, Fourier transform infrared spectroscopy and Raman spectroscopy. We have observed that the formation of the hybrid crystals can be obtained only when at least 50% of the epoxies are opened and a larger silica condensation is achieved. These conditions are reached after aging at 60 °C for 1 day, or at longer aging times when the sol is aged at lower temperatures. Transmission electron microscopy and optical polarized images have confirmed the formation of the hybrid crystals.     

Sol–gel chemistry of an aqueous precursor solution for YBCO thin films

A water based YBa₂Cu₃O_7−x (YBCO) precursor using a triethanolamine (TEA)/acetic acid complexing method to obtain YBCO thin films is described in detail. The influence of complexation behavior in the formation of transparent and homogenous sols and gels after the combination of Y, Ba and Cu—acetates, acetic acid and TEA has been studied by potentiometric titration and the results are compared with analytical simulations. The decomposition of the gel was studied by IR (infrared) and Thermal Gravimetric Analysis/Differential Thermal Analysis (TGA/DTA). The results in sol-gel chemistry can be used to decide on the necessities in the preparation of stable sol–gel precursors with a minimum amount of organic compounds. The sol–gel system was also used for the deposition of high textured superconducting thin films on STO substrates by dip coating. The synthesized YBCO showed a superconducting transition temperature of 90.95 K with narrow ΔT (2 K) for thin films. The results from X-ray diffraction show that the single phase YBCO was obtained. SEM pictures also indicate that the properties of the surface thin films are good.     

Characterization of CdS nanoparticles formed and aggregated in stearic acid Langmuir–Blodgett films by atomic force microscopy

Alternate films, which are composed of stearic acid and CdS nanoparticles were synthesized by exposing Langmuir–Blodgett (LB) films of cadmium stearate (CdSt₂) to H₂S gas at a pressure of 1 Torr. The changes of surface morphology of film with the increased reaction time were directly observed by atomic force microscopy for the first time. Before being exposed to H₂S, the surface of CdSt₂ LB film was homogeneous from microscale down to nanoscale, and it was observed that CdSt₂ molecules formed a well orderly rectangular herringbone lattice structure on the molecular scale. However, after being exposed to H₂S the ordered CdSt₂ molecules gradually changed into a disordered state, and eventually the LB film surface became rough with the apparent feature of bulk structures on the nanoscale. This change in the morphology can be attributed to the aggregation of buried CdS nanoparticles within LB films, which has been confirmed by a structured UV–visible absorption spectrum where the absorption edge is red-shifted about 0.7 eV with respect to bulk CdS. Finally, the aggregation mechanism of CdS in the LB film was analyzed.     

Nanocrystalline structure and soft magnetic properties of nickel–molybdenum alloy thin films electrodeposited from acidic and alkaline aqueous solutions

Nanocrystalline nickel–molybdenum (Ni–Mo) alloy thin films were electrochemically synthesized in acidic and alkaline aqueous solutions. Transmission electron microscope bright-field images and electron diffraction patterns of the electrodeposits made it obvious that pure Ni consists of a submicron crystalline phase with the grain diameter of several hundred nanometers, while Ni–20 %Mo alloy was composed of a nanocrystalline phase with the grain diameter of a few nanometers. It was estimated that the nanocrystalline phase of electrodeposited Ni–Mo alloy thin films was introduced by the formation of supersaturated Ni–Mo solid solution phase with Mo content in the deposit more than 20 %. Submicron crystalline pure Ni thin films were hardly magnetized in perpendicular direction to the film plane while the nanocrystalline Ni–20 %Mo alloy thin films were isotropically magnetized. It was suggested that the isotropical magnetization behavior was caused by decreasing the demagnetizing field and the magneto crystalline anisotropy with a decrease in the magnetic moment and the average crystal grain size. Coercive force of a submicron crystalline pure Ni thin film electrodeposited from an acidic aqueous solution was ca. 100 Oe while that of a nanocrystalline Ni–20 %Mo alloy thin film electrodeposited from an alkaline aqueous solution was only 1～2 Oe. Soft magnetic properties of Ni–Mo alloy thin films electrodeposited from an alkaline aqueous solution were better than that from an acidic aqueous solution and it was improved with an increase in Mo content in the deposit. It was estimated that the electrodeposited Ni–Mo alloy catalysts could be easily recovered with magnetic field less than 1 kOe.     

On the electrodialysis of aqueous H2SO4–CuSO4 electrolytes with metallic impurities

This work aims to contribute to the characterization of the electrodialysis (ED) of aqueous sulfuric acid–copper sulfate solutions. The presence of impurities such as As and Sb, typical of copper electrorefining electrolytes, is also studied. Results from kinetic studies carried out in ED cells with and without re-circulation are presented. The concentrations were: 3–9 g l⁻¹ copper, 50 g l⁻¹ sulfuric acid, 3 g l⁻¹ arsenic and 0.025 g l⁻¹ antimony; the temperatures, 22 and 44 °C; the transport rates, depending on experimental conditions, 0.2–0.6 mol h⁻¹ m⁻²of membrane for copper, 0.65–2.8 for sulfate, and 0.016–0.03 for arsenic. A speciation model has been developed and applied in order to interpret the experimental results and the performance of the studied cells has been evaluated. The main conclusion is that ED can be applied to the separation and concentration of chemical species in these systems.     

Reactive diffusion in W–Mo–Si thin films

This study reports the phase formation in the ternary thin films system Mo–W–Si. The metallic films were deposited onto Si (100) substrate by sputtering. Two kinds of samples were prepared, either by sequential deposition or by co-deposition. The phase formation was investigated by In situ X-ray diffraction measurements from 300 to 900 °C. The influence of the sample preparation, namely sequential deposition and co-deposition, on the mechanism of phase formation has been evidenced.     

Is there a dipolar interaction of like charges in thin aqueous films?

The dipole moment and the screened interaction of interfacial charges are discussed. We compare this interaction with that of parallel dipoles and show that the dipolar picture fails for charges in thin aqueous films.     

Size,zeta potential,and semiconductor properties of hybrid CdS–ZnS nanoparticles in a stable aqueous colloidal solution

Russian Journal of Physical Chemistry A - A stable aqueous colloidal solution of core–shell CdS–ZnS nanoparticles is obtained via the chemical condensation of carboxyl-containing...     

Understanding cathode materials in aqueous zinc–organic batteries

Organic electrode materials (OEMs) are being investigated as promising candidates for aqueous zinc-ion batteries (AZIBs) owing to their environmental friendliness, cost-effectiveness, and structural diversity, and tunability. Understanding the correlation between structural regulation of OEMs and their electrochemical property in AZIBs is vital to rational design of OEMs. Herein, we first discuss the fundamentals of the energy storage mechanism of OEMs. Then, strategies to improve the electrochemical performance, including the specific capacity, voltage, rate capability, and cycling stability, are elaborated from the perspective of molecular engineering. Finally, we share our views on the remaining challenges and prospects of OEMs in AZIBs.     

Electrodeposition of composite PbO2–TiO2 materials from colloidal methanesulfonate electrolytes

Journal of Solid State Electrochemistry - The influence of particles of colloidal titanium dioxide on the morphology and structure of lead dioxide electrodeposits has been investigated. The...     

Liquid–liquid extraction of trivalent americium from carbonate and carbonate–peroxide aqueous solutions by methyltrioctylammonium carbonate in toluene

Journal of Radioanalytical and Nuclear Chemistry - Liquid–liquid extraction (LLE) of microamounts of americium(III) from Na2CO3 and Na2CO3–H2O2 aqueous solution using...     

Interdiffusion without a common ion in aqueous NaCl−MgSO4 and LiCl−NaOH mixed electrolytes

When a solution of electrolyte MX interdiffuses with a solution of electrolyte NY, the transport of four different ions (M, X, N, and Y) is constrained only by electroneutrality. Because three degrees of freedom remain, the interdiffusion of two electrolytes without a common ion can produce an independent flow of a third electrolyte. This behavior is demonstrated by using Taylor dispersion to measure interdiffusion coefficients, including cross-coefficients, for NaCl–MgSO₄-water and LiCl–NaOH-water mixed electrolytes at 25°C. The measurements are made for electrolyte mole ratios of 01, 13, 11, 31, and 10 at a total electrolyte concentration of 0.100 mol L^–1. The results are used to calculate concentration profiles across NaCl(aq)/MgSO₄(aq) and LiCl(aq)/NaOH(aq) liquid junctions. The interdiffusion of NaCl and MgSO₄ produces relatively small flows of Na₂SO₄. As a result of large differences in ionic mobilities for the aqueous LiCl–NaOH system, substantial flows of NaCl develop during the interdiffusion of LiCl and NaOH.     

Liquid–liquid extraction of mercury(II) from aqueous solution using furosemide in benzyl alcohol

Journal of Radioanalytical and Nuclear Chemistry - A simple, efficient and economical liquid–liquid extraction method has been developed for quantitative extraction of mercury(II) from...     

Forces between a hard surface and an air–aqueous interface with and without films

The adsorption of particles to air–aqueous interfaces is vital in many applications, such as mineral flotation and the stabilization of food foams. The forces in the system determine whether a particle will attach to an air–aqueous interface. The forces between a particle and an air–aqueous interface are influenced by Derjaguin–Landau–Verwey–Overbeek forces (i.e. van der Waals and electrostatic forces), non–Derjaguin–Landau–Verwey–Overbeek forces (e.g. hydrophobic, hydrodynamic, structural, and capillary forces), liquid drainage, and liquid flow. As an air–aqueous interface can be deformed by a particle, the forces measured between an air–aqueous interface and a particle can differ from those measured between two hard surfaces separated by liquid. The presence of a film at an air–aqueous interface can also change the forces.