Electrodeposition of Lu-Ni alloy thin films

The electrodeposition of Lu-Ni alloy thin films from Lu(III) and Ni(II) solutions was studied in a nonaqueous dimethysulfoxide (DMSO). Different substrates have been used (platinum and copper), and the effect of them on the electrochemical behavior of the studied ions is shown. The obtained Lu-Ni alloy thin films were subjected to scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffraction analysis (XRD). The lutetium content in Lu-Ni alloy thin films increases as the potential was made more cathodic, reaching a maximum value of 28.77 at.%, and then decreases. The films were amorphous. After heat treatment of crystallization at 520 °C for 1 h, the alloy phase of Lu-Ni can be found in XRD patterns.     

Corrosion behavior of electrodeposited Wo3 thin films

In this study, nanostructured tungsten trioxide (WO₃) thin films were deposited on Indium tin oxide (ITO)-coated glass substrate using electrochemical deposition (ECD). After deposition, the films were annealed at 450 °C for 2 h in an air atmosphere. X-ray diffraction (XRD) analysis confirmed that the prepared WO₃ thin films have crystalline phases. According to the absorption measurements, the optical bandgap of the WO₃ film was calculated as Eg 2.80 eV. Based on the scanning electron microscopy (SEM) images, the surface morphology of the thin films was influenced by deposition conditions. Raman spectroscopy analysis was also used to further examine the structure and chemical compositions of the thin films. The nature of the nanostructured WO₃ thin films was studied with Electrochemical Impedance Spectroscopy (EIS) and Tafel. Nyquist, open circuit potential and Bode analysis were used to evaluate structural changing and corrosion behavior of the prepared WO₃ thin films. With the help of these measurements and analyzes, the parameters such as solution resistance (Rs), polarization resistance (Rpo), a constant phase element (CPE) and a CPE exponent (n) were calculated as 43.43 Ω cm², 2.67 × 10⁶ Ω cm², 18.45 × 10⁻⁶ Ω⁻¹ s cm⁻², 0.958, respectively. Also, the corrosion features of the WO₃ thin films were investigated with the help of tafel measurements and the corrosion potential and current values were calculated as −0.583 V and 5.09 × 10⁻¹⁵ A, respectively. It is thought that the prepared thin film might have the potential to be used industrially with these features.     

Electrodeposition of CdTe thin films onto n-Si(1 0 0): nucleation and growth mechanisms

The mechanisms related to the initial stages of the nucleation and growth of cadmium telluride (CdTe) thin films on the rough face side of a (1 0 0) monocrystalline n-type silicon have been studied as a function of different potential steps that varied from an initial value of −0.200 V to values comprised between −0.515 and −0.600 V versus saturated calomel electrode (SCE). The analysis of the corresponding potentiostatic j/t transients suggests that the main phenomena involved at short times is the formation of a Te-Cd bi-layer (BL). For potentials below −0.540 V, the formation of this bi-layer can be considered independent of potential. At greater times, the mechanisms is controlled by two process: (i) progressive nucleation three dimensional charge transfer controlled growth (PN-3D)_ct and (ii) progressive nucleation three dimensional diffusion controlled growth (PN-3D)_diff, both giving account for the formation of conical and hemispherical nuclei, respectively. Ex situ AFM images of the surface seem to support these assumptions.     

Properties of electrodeposited nanocrystalline Ni-B alloy films

The influence of the boron content on the various properties of nanocrystalline Ni-B alloy produced by electrodeposition was investigated. The considerable reduction in grain size was observed with increasing boron content. The internal stress was tensile and increased linearly with increasing boron content. Hardness increased up to 750 Hv at 2 at.% boron and then kept the value to 11 at.% boron for as-plated Ni-B coatings.The hardness of Ni-B films increased considerably due to the intermetallic Ni₃B precipitation by the heat treatment and maximum hardness of each coating increases with boron content. Wear resistance decreased with increasing the boron content because of high friction coefficient and brittle fracture of coating with high content of boron.     

Effects of photo-assisted electrodeposited on CuInSe2 thin films

Photo-assisted one-step electrodeposition has been applied to help in forming smooth and dense CuInSe₂ films. The difference in surface morphology and crystalline quality between CuInSe₂ films with various photo-assistance has been investigated. In the photo-assisted electrodeposition process, the many kinds of lamps providing maximum light intensity at about 380 to 620 nm were used as light source to be irradiated onto the surface of Mo-coated soda-lime glass substrates. The results suggested effects of photo-assistance including activating surface diffusion and growing high-crystalline quality films with reduced defects during electrodeposition.     

Nanostructured Fe-Pd thin films for thermoelastic shape memory alloys—electrochemical preparation and characterization

Nanostructured Fe-Pd thin films with about 30 at.% Pd have been successfully synthesized on the substrates of Pt buffer layer/Cr seed layer/Si by an electrodeposition process from a plating bath containing ammonium tartrate, citric acid and ammonia solution as complexing agents. Results clearly show that the as-deposited films with body-centered cubic structure were transformed into face-centered cubic structure by heating at 900 °C for 45 min followed by quenching into iced water. The in situ X-ray diffraction analysis results indicate that the quenched film with 29.8 at.% Pd undergoes a reversible thermoelastic austenite-to-martensite transformation with a narrow temperature hysteresis and a martensite transformation temperature of about −30 °C. The present study demonstrates the effectiveness of electrodeposition for synthesizing nanostructured Fe-Pd thin films for the application of low-temperature-type thermoelastic shape memory alloys.     

Electrochemical behaviour of dysprosium in the eutectic LiCl-KCl at W and Al electrodes

The electrochemical behaviour of DyCl₃ was studied in the eutectic LiCl-KCl at different temperatures. The cathodic reaction can be written:

Dy(III) + 3e ↔ Dy(0)     

Electrochemical deposition and characterization of ZnCo alloys and corrosion protection by electrodeposited epoxy coating on ZnCo alloy

ZnCo alloys electrochemically deposited on steel under various deposition conditions were investigated. The influence of deposition current density, temperature and composition of deposition solution on the phase structure and corrosion properties of ZnCo alloys were studied. It was found that ZnCo alloy obtained from chloride solution at 5 A dm⁻² showed the best corrosion properties, so this alloy was chosen for further examination. Epoxy coating was electrodeposited on steel and steel modified by ZnCo alloy using constant voltage method. The effect of ZnCo alloy on the corrosion behavior of the protective system based on epoxy coating is interpreted in terms of electrochemical and transport properties, as well as of thermal stability.     

Stress behavior of electrodeposited copper films as mechanical supporters for light emitting diodes

Thick copper films electrodeposited on vertically structured GaN-based LEDs play a critical role in supporting thin GaN multi-layers mechanically after laser lift-off (LLO) of the sapphire substrate. The intrinsic stress of electrodeposited copper was measured from the change in the substrate's curvature using a modified Stoney equation. 150-μm thick copper supporters showed very low intrinsic stress of 4-28 MPa (tensile stress), which developed during copper electrodeposition on Au seed. The stress generation was attributed to nuclei coalescence and formation of grain boundaries of which volume increased with the applied current density. The preferential texture plane of thick copper supporters was (2 2 0) at high current densities, while copper films thinner than 1 μm was strongly oriented along (1 1 1) plane. Various seed metals such as Cu, Ni, Au, Ag, and Al were employed to observe the influence of seed material on the stress of copper supporters. The effect of wetting agent on the stress of copper supporters was also monitored in the concentration range of 0.1-1.5 g/L of sodium lauryl sulfate (SLS).     

Electrodeposition of indium onto Mo/Cu for the deposition of Cu(In,Ga)Se2 thin films

A study of the electrodeposition and the oxidation process of indium on Mo/Cu substrates from a bath containing 0.008 M InCl₃, 0.7 M LiCl at pH 3 is described in this work. The voltamperometric study showed a reduction process which corresponds to the conversion of In³⁺ to In⁰ and an oxidation process which takes place in different steps. Utilizing the chronoamperometric technique the total efficiency of process, the number of monolayers, the film thickness and the diffusion coefficient were evaluated. The analysis of current transients, using theoretical growth model, showed that the electrodeposition of indium adjusts to a three-dimensional growth under instantaneous nucleation limited by diffusion. The kinetic growth parameters were evaluated through a non-linear fit. The films were characterized by X-ray diffraction and scanning electron microscopy techniques. These studies showed that the films were of crystalline in nature with compact and uniform surface, even for the film with a deposition time of 1 min.     

电沉积Co-Mo合金薄膜的结构和热稳定性

通过电沉积,在铜基体上制备了Co-Mo合金薄膜.讨论了薄膜组成与结构以及非晶合金的晶体结构与热处理温度的关系.测定了薄膜磁性能(饱和磁化强度和矫顽力)随热处理温度变化的关系曲线.结果表明,薄膜中钼含量(质量分数)为6.05%～30.03%时,镀态Co-Mo合金薄膜具有非晶态结构;经连续升温到400℃并热处理1.5 h后,Co-Mo非晶态合金发生晶化,且随着薄膜中钼含量的增加,薄膜的晶化温度提高,热稳定性增强;在较高温度(高于500 ℃)下热处理后,Co-Mo非晶态合金晶化,并析出单一的hcp-Co相;热处理后,Co-Mo合金薄膜的软磁性变差.     

Electrochemical nucleation and growth of Co and CoFe alloys on Pt/Si substrates

Electrochemical nucleation and growth of Co and CoFe alloys on Pt/Si(1 0 0) surface from watts (mixed chloride sulfate) baths were studied by voltammetric, chronoamperometric and AFM measurements. The CoFe alloys were deposited from solution with molar ratio of (1/1) and (10/1). The Scharifker and Hills model was employed to analyse the current transients. For both Co and CoFe (10/1) alloys the nucleation was a good agreement with the instantaneous model followed by 3D diffusion-limited growth. Inversely, for CoFe (1/1) alloy the nucleation was an agreement with the progressive model. It is evident that the compositions of the electrolyte influence greatly the type of nucleation. The atomic force microscopy (AFM) images revealed a compact and a granular structure of the electrodeposited Co layers and CoFe alloys.     

Stability of iodine on ruthenium during copper electrodeposition and its effects on the nucleation behavior of electrodeposited copper

Cyclic voltammetry, current-time-transient measurements, and X-ray photoelectron spectroscopy (XPS) have been used to study the nucleation behavior of electrochemically deposited Cu films on Ru substrates as a function of Ru pre-treatment. Pre-treatment consisted of cathodic polarization in either 1 M H₂SO₄ or in 1 M H₂SO₄ + 1 mM KI, followed by sample emersion and placement in a 1 M H₂SO₄ + 50 mM CuSO₄ plating bath. XPS measurements confirmed the presence of adsorbed I on the Ru surface following pre-treatment in the KI/H₂SO₄ solution. Cyclic voltammogram (CV) data for electrodes either as-received or pre-reduced in H₂SO₄ and then immersed in the plating solution exhibited a broad peak in the overpotential region consistent with oxide reduction followed by Cu deposition. No underpotential deposition (UPD) feature was observed for these electrodes. In contrast, the sample pre-reduced in I-containing electrolyte exhibited a narrow Cu deposition peak in the overpotential region and a UPD Cu feature centered at 80 mV vs. Ag/AgCl. Current-time-transient (CTT) measurements of Cu deposition on as-received electrodes or electrodes pre-reduced in I-free solution exhibited potential-independent kinetics that are not well described by either progressive or instantaneous nucleation models and which at long times indicate a combination of diffusion and kinetic control. In contrast, CTT measurements of deposition kinetics for samples reduced in I-containing electrolyte exhibited complex, potential-dependent behavior and that at long times indicates diffusion control. XPS results also indicated that the iodine adlayer on Ru reduced in I-containing electrolyte is stable upon polarization to at least −200 mV vs. Ag/AgCl. These data indicate that a protective I adlayer may be deposited on an air-exposed Ru electrode as the oxide surface is electrochemically reduced, and that this layer will inhibit reformation of an oxide during the Cu electroplating process. Therefore, electrochemical pre-treatment in I-containing electrolyte may be of practical utility under industrial conditions for Cu electroplating.     

Characterization of electrodeposited Cd–Co alloy coatings by anodic linear sweep voltammetry

The electrodeposited Cd–Co alloys were characterized by the anodic linear sweep voltammetry (ALSV) technique in the solution of 1 M NaCl (pH 2). It is shown that Cd–Co alloys could be deposited with high current efficiency (>90%) from the solution containing 0.2 M boric acid, low concentration of cadmium sulfate (0.01 M and 0.02 M) and high concentration of cobalt sulfate (0.2 M and 0.4 M) under the conditions of convective diffusion (RPM = 1000). The ALSVs were characterized by the presence of three peaks: one corresponding to the dissolution of pure Cd, one corresponding to the dissolution of pure Co and one corresponding to the dissolution of unknown phase formed in the system Cd–Co (since the phase diagram of the Cd–Co system does not exist in the literature). Depending on the charge and on the alloy composition (amount of Cd and Co) the peak of the unknown phase can either be hardly seen, or can prevail on the ALSV. This phase is formed mainly on the account of Co, but certain limiting amount of Cd must be deposited for the unknown phase to be formed and seen on the ALSV.     

Synthesis and characterization of electrodeposited samaria and samaria-doped ceria thin films

Samaria (Sm₂O₃) and samaria-doped ceria (SDC) films are electrochemically deposited on stainless steel in view of a potential use in solid oxide fuel cells. As it is possible to deposit separately pure ceria (CeO₂) and pure samaria (Sm₂O₃) in similar conditions, SDC films were successfully obtained in one electrochemical conditions set. Thin films have been fabricated at low-temperature (30 °C) by applying a cathodic potential of −0.8 V/SCE, for 2 h. Structural and morphological properties of electrodeposited films have been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), techniques and Raman spectroscopy. Special attention has been focused on the Raman spectroscopy study to emphasize the effect of heat treatment and samarium doping. Despite cracks, single SDC phase was obtained crystallizing in a cubic symmetry.     

The kinetics of copper island growth on ruthenium oxide in perchlorate solution

The nucleation potential for the deposition of copper on ruthenium oxide is very small and hence island growth can occur in the kinetic regime. Previously, we have reported on island growth in sulfate solution where anion adsorption results in the formation of hexagonal, disk-shaped islands. Here we report on island growth in perchlorate solution, in the absence of specific anion adsorption. All islands have a 〈1 1 1〉 surface orientation dictated by the amorphous substrate. The islands are hemispherical in shape and island growth follows power law kinetics in both lateral and vertical directions with exponents 0.50 and 0.26, respectively. From analysis of the time-dependent extended area using Avrami analysis, analysis of the near-neighbor distribution, and the correlation between the island size and the spatial distribution, we conclude that island growth is controlled by surface diffusion-mediated lateral growth.     

Multi-electrochromism behavior and electrochromic mechanism of electrodeposited molybdenum doped vanadium pentoxide films

Molybdenum doped vanadium pentoxide (Mo doped V₂O₅) films are prepared by cathodic electrodeposition on indium tin oxide substrate from Mo doped V₂O₅ sol. As an anodic and cathodic coloration electrochromic material, the electrodeposited Mo doped V₂O₅ film presents a better cycling stability, reversibility and multi-electrochromic behavior (orange-yellow-green-blue) with an optical modulation of 60-90% in the spectral region 550-900 nm, which can be expected as a result of enhanced electron intervalence transfer between Mo⁶⁺ and V⁵⁺, V⁴⁺ states, in addition to V⁵⁺ and V⁴⁺ transition. The electrochromic mechanism of Mo doped V₂O₅ films is investigated with atomic force microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy. The surface roughness of the film increase at the different coloration states due to the increasing crystallinity degree. The change of the interlayer spacing for the host V₂O₅ and the change of the C and Li element states verify the insertion of organic solvent into the interlayer of the host V₂O₅ and some of the Li⁺ ions into the sites in the V-O layers. The electrochromic kinetics process indicates that the electrochromism of Mo doped V₂O₅ films can be considered as a reversible reduction/oxidation process accompanying the insertion/extraction of Li⁺ ions and electrons.     

Electrochemical behaviour of erbium in the eutectic LiCl-KCl at W and Al electrodes

The electrochemical behaviour of Er(III) was studied in the molten LiCl-KCl eutectic for temperatures ranging from 653 to 823 K. Transient electrochemical techniques, such as cyclic voltammetry, chronopotentiometry and chronoamperometry were used in order to study the reaction mechanism and the transport parameters of electroactive species at a tungsten electrode. The results showed that in the eutectic LiCl-KCl, the reduction of Er(III) occurs in a step with a global exchange of three electrons, and that electrocrystallization plays an important role in the electrodeposition process. Chronoamperometric studies indicated instantaneous nucleation of erbium with three-dimensional growth of the nuclei whatever the applied overpotential.Mass transport towards the electrode is a simple diffusion process, and the temperature dependence of the diffusion coefficient of the electroactive specie Er(III) was written in the following equation:

     

Study of phase composition of Zn-Ni alloy electrodeposited in acetate-chloride electrolyte at a temperature of 50 °C

The phase composition of Zn-Ni alloys electrodeposited under potentiodynamic and galvanostatic conditions in acetate-chloride plating solution with the ratio [Zn⁺²]/[Ni⁺²] = 1:12.8 at 50 °C has been investigated by the potentiodynamic stripping and XRD methods. It has been determined that two anodic peaks, which can be attributed to oxidation of the certain phases of Zn-Ni alloy emerged in potentiodynamic stripping curves (PDC) at E < 0 V and at E > 0 V. The Zn-Ni alloy phase that oxidized at E > 0 V was obtained by using cyclic voltammetry with the partial potentiodynamic stripping. This phase is ∼7 at.% Zn solid solution in Ni. The composition of Zn-Ni alloy phase that oxidized at E < 0 is ∼41.0 at.% Zn and ∼59.0 at.% Ni. The ratio of these phases in the alloys depends on the cathodic current density (i_c).     

The effect of Fe on magnetic moment of electrodeposited CoFe alloys—Experimental study and analytical model

The effect of Fe³⁺ concentration on saturation magnetic flux density (B_s) of electrodeposited Co_40-44Fe_60-56 films was investigated. The results show that if the conditions at the electrochemical interface for nucleation/precipitation of iron(III) hydroxide (Fe(OH)₃) are reached, the B_s of electrodeposited Co_40-44Fe_60-56 films quickly decreases as a result of the Fe(OH)₃ incorporation into deposit. These conditions are discussed as a function of the solution formulation (pH) and the parameters of electrodeposition process (current density, current efficiency, diffusion layer thickness) and a simple analytical model is developed qualitatively describing the hydroxide incorporation phenomenon and resulting decrease in B_s of Co_40-44Fe_60-56 films.