Nitrate Bath Research Articles

Electrodeposition and morphology analysis of Bi–Te thermoelectric alloy nanoparticles on copper substrate

Nanoscale Bi–Te particles with thermoelectric properties on copper substrate were investigated. The substrate was prepared by electroplating copper layer on a copper zinc alloy plate in a copper sulfate solution. Electrodeposition of the Bi–Te alloy particles was then performed in a nitrate bath. The electrolyte is composed of 0.05 M bismuth nitrate and 0.01 M tellurium dioxide dissolved in 2.0 M HNO 3. Cyclic voltammetry and quartz microbalance tests associated with the electrodeposition process were conducted to show the mechanism and kinetics of the deposition. The morphology and compositional analysis of Bi–Te was obtained using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) respectively. The morphology analysis suggested that nanoscale Bi–Te particles were obtained and the EDS results indicated that the surface of the copper substrate contained Cu 2O. The atomic ratio 1:1 for Bi:Te in the alloy, which is equivalent to the weight percentage of Bi:Te = 62%:38% was confirmed from the data obtained.

Effect of NaCl and CaCl2 additives on NaNO3 bath nitriding of steel

A study has been made of nitriding of interstitial-free steel sheet specimens in the sodium nitrate bath. The nitriding rate increased when the bath contained a small amount of sodium chloride and calcium chloride. Accordingly, the tensile strengths and hardness values of the steel specimens nitrided in the chloride containing bath were higher than those of the same steel specimens nitrided in the pure nitrate bath when the nitriding time and temperature were controlled so that the excessive formation of brittle compound Fe4N could be prevented.

Growth and Characterization of Ordered PbO2 Nanowire Arrays

Large arrays of nanowires having high aspect ratios (length-to-width ratio) were grown by potentiostatic electrodeposition into anodic alumina templates under anodic polarization. Different electrolytic solutions were used in order to obtain nanowires of pure , pure , and a mixture. We have found that, in a lead nitrate bath, a crystallographic structure of nanowires depends on pH; this latter was varied adding diluted nitric acid to the electrolyte. Nanowires of pure were obtained at pH 0.6, while mixed nanowires were grown at pH 2. Pure α–phase was obtained in a bath containing lead acetate at pH 6.6. In all deposition conditions, nanowires present the same morphology: perfectly cylindrical wires having uniform diameters throughout length, with an average value of and a population density on the order of wires/. Very high aspect ratios were obtained already after of electrodeposition.

Structures and characteristics of Cr(III)-based conversion coatings on electrogalvanized steels

Trivalent chromium (Cr(III)) conversion coatings have been made on electrogalvanized steels in the solutions containing Cr(III) sulfate, nitrate, and chloride among which the sulfate, nitrate, and chloride anions function as passivating, oxidizing, and pitting agents, respectively. The structure and properties of the Cr(III) conversion coatings were examined by electrochemical methods and surface morphology observations. Experimental results showed that the Cr(III) coating formed in the sulfate bath displayed a thin, compact, single-layered structure, before and after baking. The conversion coating formed in the nitrate bath consisted of two porous layers for both the as-deposited and baked states. Moreover, the coating prepared in the chloride bath exhibited a porous, single-layered structure regardless of the baking treatment. Electrochemical impedance analyses further showed that the anions in the bath strongly influenced the structure and corrosion resistances of the Cr(III) coatings.

Fabrication of ZnO Nanowire Devices via Selective Electrodeposition

We introduce a solution-based electrodeposition technique that selectively deposits copper only at the contacts between nanowires/ nanobelts/nanotubes and the electrodes, while leaving the device surfaces clean. This was achieved using a copper nitrate bath with low covering power. Our method demonstrates an effective, parallel process for achieving stable electric and mechanical contacts for one-dimensional nanomaterial-based devices on a large scale.

Morphology-tunable synthesis and characterizations of Mg(OH) 2 films via a cathodic electrochemical process

An electrodeposition route for preparation of well-controlled magnesium hydroxide nanostructure using sodium acetate as structure-directing agent was presented. The magnesium hydroxide thin films were characterized by XRD, SEM and TEM. The influence of synthesis parameters on the morphological characteristics and size of magnesium hydroxide thin films deposited from nitrate bath was investigated, such as concentration of sodium acetate additive and applied potential. A possible mechanism responsible for morphologies evolution of thin films was also elucidated. This electrochemical process may be extended to fabricate other nano-/mesostructures with diverse morphologies and unique properties under convenient and mild conditions.

Electrosynthesis and characterization of lead oxide thin films

Lead dioxide (PbO 2) is an important oxide material used extensively as anode material in batteries and fuel cells and its study has now taken new strides beyond the wide field of battery research. In the present study, lead dioxide films were electrodeposited onto precleaned copper substrate from nitrate baths. The film composition, morphology and structure were investigated using Energy Dispersive X-ray Analysis (EDX), scanning electron microscopy and X-ray diffraction techniques. The oxidation and reduction potential regions and the mechanism of lead dioxide film formation are discussed using cyclic voltammetry studies. X-ray diffraction results revealed tetragonal [α-PbO 2 + β-PbO 2] structures of the films which are influenced by bath temperature and solution pH value. EDAX studies show that the films deposited at higher bath temperatures and low solution pH values are rich in lead content and low in oxygen content. The effects of bath temperature and solution pH on the morphological features of lead dioxide films are also described.

Highly textural lamellar mesostructured magnesium hydroxide via a cathodic electrodeposition process

Highly textural lamellar mesostructured Mg(OH) 2 thin films were obtained through one-step cathodic reduction of magnesium nitrate bath without any surfactant template at room temperature. Its microstructure, stability and morphology were investigated using XRD, TEM, FT-IR, thermal analysis and SEM technique respectively. The results indicate that the porous hydroxide/oxide materials have highly textural lamellar structures with layer spacing around 3.4 nm. The possible formation mechanism has been discussed.

Electrodeposition of PbTe thin films from acidic nitrate baths

Electrodeposition of PbTe thin films from an acidic nitric bath was systematically investigated to understand the kinetics and the effect of electrodeposition conditions on film composition, crystallographic structure, texture and grain size. The electroanalytical studies employed initially with a rotating disk electrode to investigate the kinetics associated with Te, Pb and PbTe electrodeposition. The results indicated that the PbTe thin films were obtained by the underpotential deposition (UPD) of Pb atoms onto the overpotentially deposited Te atoms on a substrate. Based on these studies, PbTe thin films were potentiostatically electrodeposited using e-beam evaporated gold thin films on silicon substrate to investigate the effect of various deposition conditions on film composition and microstructure. The data indicated that the microstructure, composition and preferred film growth orientation of PbTe thin films strongly depended on the applied potential and electrolyte concentration. At −0.12 V, the film was granular, dense, and preferentially oriented in the [1 0 0] direction. At potentials more negative than −0.15 V, the film was dendritic and preferentially oriented in the [2 1 1] direction. A smooth, dense and crystalline film with nearly stoichiometric composition was obtained at −0.12 V from a solution containing 0.01 M HTeO 2 +, 0.05 Pb 2+ and 1 M HNO 3.

Electrosynthesis of Bi 2O 3 thin films and their use in electrochemical supercapacitors

Bismuth oxide (Bi 2O 3) thin films are grown on copper substrates at room temperature by electrodeposition from an aqueous alkaline nitrate bath. The usefulness of electrochemically deposited Bi 2O 3 for electrochemical supercapacitors is proposed for the first time. The supercapacitor properties of Bi 2O 3 electrode are studied in aqueous NaOH solution. The Bi 2O 3 electrode exhibits very good electrochemical supercapacitive characteristics as well as stability in aqueous NaOH electrolyte. The effect of electrolyte concentration, scan rate, and number of cycles on the specific capacitance of Bi 2O 3 electrodes has been studied. The highest specific capacitance achieved with the electrodeposited Bi 2O 3 films is 98 F g −1.

Electroforming of Copper/ZrB<sub>2</sub> Composites Coatings and Its Performance as Electro-Discharge Machining Electrodes

Copper electroforming, together with rapid prototyping (RP) technology, provides a method for manufacturing EDM electrodes rapidly. However, the use of conventional electroformed copper electrodes is restricted because of the high electrode wear rate in EDM processes. This paper presents a study on the electroforming technique of copper/zirconium diboride (ZrB2) composite coating and its performance as an EDM electrode. Cu-ZrB2 composite coating is electroformed from a copper nitrate bath containing micro-sized ZrB2 particles in such a way that by varying the process parameters, ZrB2 particles approximate to 20 Vol.% are incorporated in the coatings. Analyses by optical microscopy and scanning electron microscopy reveal that ZrB2 particles are uniformly dispersed in the copper matrix and the grains of the coating are refined due to the incorporation of ZrB2 particles. The electroformed coatings deposited on copper substrates with approximately 1mm thickness are used as electrodes. EDM experiment shows that performance such as the spark-resistance of the new electrodes is improved compared with that of conventional electroformed copper electrodes because the incorporation of refractory particles in the copper matrix as well as the refinement of the grains of the coating, and the. Cu-ZrB2 composites show good performance in finish machining condition.

Room temperature electrodeposition and characterization of bismuth ferric oxide (BFO) thin films from aqueous nitrate bath

Bismuth ferric oxide (BFO) thin films were prepared on fluorine doped tin oxide (FTO) coated glass substrates using electrodeposition method from aqueous nitrate bath at room temperature. The various preparative parameters, such as bath composition, current density, deposition time, etc were optimized to get good quality BFO thin films. The structural, surface morphological, optical and dielectrical properties of the films were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), optical absorption and dielectric measurement techniques. The results show that electrodeposition method allows to synthesis BFO films. The films are free from pinholes and cracks. The magnitudes of dielectric constant and loss tangent showed inverse frequency dependence.

Mechanism of cathodic electrodeposition of zinc oxide thin films from aqueous zinc nitrate baths

Mechanism of electrodeposition of zinc oxide (ZnO) thin films from aqueous solution of zinc nitrate has been studied under controlled mass transport by using a rotating disk electrode. The current associated with the electroreduction of nitrate ion has not been affected by the rotation speed due to slow electron transfer kinetics. Rate constant and transfer coefficient have been determined as 5.98×10 −10 cm s −1 and 0.159, respectively, for the electrolysis in a 0.1 M Zn(NO 3) 2 aqueous solution. The current, however, is increased by increasing Zn 2+ concentration in the bath. The improvement of the electron transfer kinetics has been interpreted as the catalytic role of Zn 2+ ion to the reduction of nitrate. The current in the presence of Zn 2+ at various concentrations has been nicely described by Langmuir type adsorption of Zn 2+ catalysts to the surface sites of ZnO, for which an equilibrium constant of 1.23×10 5 cm 3 mol −1 (70 °C) has been determined.

The effect of nickel electrodeposition on magnetic properties of CoFeSiB amorphous wire

Abstract Nickel films were electrodeposited on rapidly quenched amorphous wires from nitrate bath using a constant voltage. It was found that the pH of plating bath had a very strong effect on the formation of nickel films. The magnetic field, H , dependence of the impedance, of nickel plated (Co 0.94 Fe 0.06 ) 72.5 Si 12.5 B 15 wires have been investigated using a Hewlett-Packard 4294A impedance analyser with 42941A impedance probe. The best elecroplating condition and GMI response were obtained for the plated wire at pH 5 for 30 min plating time.

Cathodic Electrodeposition of ZnO/EosinY Hybrid Thin Films from Dye Added Zinc Nitrate Bath and Their Photoelectrochemical Characterizations

Cathodic Electrodeposition of ZnO/EosinY Hybrid Thin Films from Dye Added Zinc Nitrate Bath and Their Photoelectrochemical Characterizations

Dissolution Susceptibility of the Oxide Species Formed on Mild Steel During Its Oxidation in Molten NaNO<SUB>3</SUB>-KNO<SUB>3</SUB> Eutectic Mixture

Mild steel was oxidized in pure molten NaNO3-KNO3 eutectic mixture at temperatures of 300, 375, and 450 °C and in the presence of 0.05 molal KH2PO4, K2Cr2O7, or Na2O2 as additives. The dissolution susceptibility of the formed oxide species was evaluated in H2SO4 acid solution using the potential-time and current-time measurements under the open-circuit conditions. It was found that the rate of dissolution depended on the composition of molten nitrate bath, used for oxidation of mild steel, and its temperature. This was attributed to the effect of the previous conditions of the nitrate bath on the nature and composition of the oxide species formed on the metallic surface. The more resistant to dissolution in H2SO4 solution were those electrodes that were oxidized in nitrate melt at 450 °C in the presence of K2Cr2O7 or Na2O2 as additives.

Influence of Chloride and Nitrate Anions on Copper Electrodeposition in Ammonia Media

Copper electrodeposition onto a glassy carbon electrode (GCE) was investigated using linear sweep voltammetry and a potential step technique in M 1 M and pH 10.5, in the presence of chloride and nitrate anions. Voltammetric analysis showed that copper electrodeposition is carried out in two steps. The first step corresponds to couple managed by diffusion control, whereas in the second, the reduction of to Cu(0) is influenced by and anions. In the case of chloride and chloride and nitrate baths, it may be observed that only 40-60% of deposited copper is oxidized in the reverse potential sweep; these low charge recoveries are due to an disproportionation stage: the newly deposited copper reacts with the Cu(II) present in the reaction layer to form Cu(I). For baths containing only nitrates, the efficacy of charge recovery is even smaller (20%) due to an interaction between newly deposited copper and nitrate ions that could include a direct redox reaction and/or nitrate reduction on the surface of copper nuclei, this reaction provokes an additional dissolution of copper nuclei. The presence of chlorides in nitrate-containing baths seems to block said interaction between nitrates and newly deposited copper. Through the analysis of current transients, copper electrocrystallization on GCE is shown to be performed by means of a three-dimensional nucleation growth diffusion-limited mechanism in the presence of the three electrolytes studied here. However, the presence of anions directly influences the magnitude and dependence of kinetic parameters of copper electrocrystallization with the applied potential. © 2001 The Electrochemical Society. All rights reserved.

Effects of copper and anions on zinc–nickel anomalous codeposition in plating and electrowinning

Anomalous codeposition describes inhibition of the reduction of a metal such as Ni by the presence of a less noble metal such as Zn. This phenomenon is observed in two important industrial applications. In the case of plating, it is shown that the addition of Cu leads to the formation of a ternary alloy which is enriched in Ni in the chloride bath, whereas little enrichment is observed in the sulfate, and none in the nitrate and acetate baths. In the case of Zn electrowinning with diluted metallic impurities, a description of the anomaly based on limiting current density is given, and once again the effect of Cu, which is to increase the content of the Ni impurity in the Zn, is much more important in the chloride than in the sulfate media.

Synthesis and Diagnostic Electrochemistry of Nanocrystalline Li1 + xMn2 − x O 4 Powders of Controlled Li Content

Fine powders of cathode materials were synthesized by a nitrate route based on the Lux‐Flood principle. The method involves the reaction of with an excess of nitrate from a nitrate bath. The reaction consists of three steps, dehydration, oxidation, and lithiation. Cathode powders with a grain size of ∼100 nm were made and tested in rechargeable lithium batteries for their capacity retention and high discharge current behavior. Despite the small diffusion path offered by these nanosized grains during lithium insertion, the electrochemical performance of the cathode was not improved. The observed discharge profiles are interpreted in terms of current density—dependent mixed insertion into tetrahedral and octahedral sites. A quantitative analysis of the capacity retention data for Li‐substituted and stoichiometric cathodes suggests that is immune to dissolution in the electrolyte. These results are interpreted as establishing that the dissolution of the cathode and the structural fatigue induced by the Jahn‐Teller distortion are correlated through the formation of at the grain surface. © 2000 The Electrochemical Society. All rights reserved.

Factors governing the electrochemical synthesis of α-nickel (II) hydroxide

The electrodeposition of α-nickel hydroxide is promoted by the simultaneous chemical corrosion of the electrode by an acidic nitrate bath. Chemical corrosion results in the formation of a poorly ordered layered phase which is structurally similar to α-nickel hydroxide and provides nucleation sites for the deposition of the latter. Therefore under conditions which enhance corrosion rates such as low current density (<1.3 mA cm−2), high temperature (60 ∘C), high nickel nitrate concentration (≥ 1M) and the resultant low pH (∼1.7), α-nickel hydroxide electrodeposition is observed, while β-nickel hydroxide forms under other conditions. Further, α-nickel hydroxide deposition is more facile on an iron electrode compared to nickel or platinum.