Morphology and Rietveld analysis of nanostructured Co-Ni electrodeposited thin films obtained at different current densities (original) (raw)

Effect of pH and current density in electrodeposited Co–Ni–P alloy thin films

Materials Chemistry and Physics, 2008

Co-NiP alloy thin films have been electrodeposited from sulfate baths at various solution pH and current density values. The effect of pH and current density on compositional, structural, morphological, and magnetic properties of these films was investigated by EDAX (energy dispersive analysis of X-ray spectroscopy), XRD (X-ray diffractometer system), AFM (atomic force microscope) and VSM (vibrating sample magnetometer). The reaction mechanism of individual deposition of Co, Ni and Co-NiP were investigated by cyclic voltammetry. The EDAX results revealed that cobalt and phosphorous content were high and nickel content was low at high solution pH and at low current density. X-ray diffraction studies exhibit that the intensity of hcp and Co-NiP amorphous phases increases and the intensity of fcc phase decreased when increasing the solution pH and decreasing the value of current density. The surface morphology of the films were observed by AFM. The deposited films exhibit hard magnetic properties at high pH value and soft magnetic properties at low pH value.

Characteristics of Thin Cu Films Electrodeposited On Textured Ni-Co Substrates

IOP Conference Series: Materials Science and Engineering, 2018

An attempt has been made to study the effects of current density and the texture of the underlying substrate on electrodeposited copper. For this purpose five Ni-Co alloys, Ni-10 Co, Ni-20 Co, Ni-30 Co, Ni-40 Co and Ni-60 Co, in the cold rolled as well as in the annealed conditions, were used as substrates. Acid copper sulfate solution was used to deposit thin Cu layers on the substrates, using a Cu plate as anode, at four different current densities, 1, 10, 30 and 50 mA/cm 2. The thickness of the electrodeposited Cu layer increased nearly linearly with current density, but was independent of the texture and composition of the underlying substrate. In general, the X-ray diffraction line intensities for the deposited Cu layer sharpened and those for the substrate Ni alloys weakened with increase in current density. The textural developments in the Cu deposits appeared to be quite independent of the textures as well as the compositions of the substrate materials. The deposited Cu layers did not inherit the textures of the substrates at the lower current densities, and also developed their own textures at higher current densities. The Cu (220) peak ultimately became the strongest XRD peak for the electrodeposited layer. The surface roughness of the deposited layers was distinctly smoother for the annealed substrates, as compared to the cold rolled Ni-Co alloys.

A study on electrodeposited Co–Mo alloys thin films

Journal of Materials Science: Materials in Electronics, 2013

Cobalt-Molybdenum (Co-Mo) induced electrodeposition has been studied from a sulphate bath on Ru electrodes at pH 4. The conditions of electrodeposition of Co-Mo alloys were determined using the cyclic voltametry at different ions concentration ratios. The theoretical model of Scharifker-Hills was used to analyse the current transients for studying the first stage of nucleation of Co-Mo alloys. The electrodeposited coatings were analysed by scanning electron microscopy, X-rays diffraction and alternating gradient force magnetometer techniques. The cyclic voltametry shows that the codeposition of Co-Mo alloys was accompanied by concurrent reactions such as the formation of the molybdenum oxides and the hydrogen evolution reaction. For the electrodeposited Co-Mo, the nucleation is in good agreement with the instantaneous nucleation and three-dimensional (3D) diffusion-limited growth. Co-Mo thin films of an hcp structure have been obtained, and the electrodeposition parameters such as the applied potential have a great influence on the structure, morphology and magnetic properties.

Electrodeposited Co–Ni Films: Electrolyte pH—Property Relationships

Journal of Superconductivity and Novel Magnetism, 2013

The effect of electrolyte pH on structural, magnetic, and magnetoresistive properties of Co-Ni films was studied. The films were deposited on a titanium substrate from the electrolytes with 4.10 ± 0.05, 3.14 ± 0.05, and 2.14 ± 0.05 pH values. The Co-Ni system exhibited anomalous codeposition. Structural analysis indicated that the films had (220) preferential oriented face-centered cubic structure and their surface became smoother as the electrolyte pH decreased. The compositional and magnetic analysis revealed that an increase of the Co content in the films resulted in an increase in saturation magnetization and coercivity. Magnetoresistance curves indicated that the films show anisotropic magnetoresistance. Longitudinal and transversal magnetoresistances were found to be the highest values of 8 % and 7 %, respectively, for the film deposited at a low electrolyte pH. The variation of the Co:Ni ratio in deposits caused by the change of the electrolyte pH has a considerable effect on the properties of the films.

Electrochemical nucleation behaviours and properties of electrodeposited Co–Ni alloy thin films

Transactions of the IMF, 2013

The electrocrystallisation of Co, Ni and Co-Ni alloys on ruthenium surface from chloride baths has been studied by cyclic voltammetry and chronoamperometry measurements. The structural and magnetic properties were studied by X-ray diffraction and alternating gradient force magnetometer techniques respectively. The Co-Ni alloys were deposited from solution with molar ratios (Co/Ni) of 5 : 1, 1 : 1 and 1 : 5. From cyclic voltammetry measurements, for all molar ratios for electrodeposited Co-Ni, preferential deposition of Co occurs and anomalous codeposition takes place. Therefore, variation in the composition of thin films alloy is possible depending on the deposition potential. The Scharifker and Hills model was employed to analyse the current transients. For both Co and Co-Ni alloys, the nucleation was a good agreement with the instantaneous model followed by threedimensional diffusion limited growth. However, for Ni after t max , the nucleation process changes from progressive to instantaneous model. It is evident that the compositions of the electrolyte do not have influence on the type of nucleation for Co-Ni alloys. X-ray diffraction measurements indicate a small crystallite size with the presence of a mixture of hcp and fcc Co-Ni structures. The hysteresis loops with a magnetic field in the parallel and perpendicular directions showed that the easy magnetisation axis of Co-Ni thin film is in the film plane.

Composition Dependence of Structural and Magnetic Properties of Electrodeposited Co-Cu Films

IEEE Transactions on Magnetics, 2000

The structural and magnetic properties of Co-Cu films were studied in terms of Co content in the films. The surface morphology of the films showed that the film with the lowest Co content (3 wt. %) had dendritic structures, whereas the surface of the film containing the highest amount of Co (61 wt. %) was more uniform with acicular shapes in some parts. X-ray diffraction patterns of the films showed that their crystal structure is a mixture of dominantly face-centered cubic (fcc) and hexagonal close-packed phases. At the lowest Co content, separate fcc (111) peaks appear, whereas the increase of Co content converts the peaks to be a single broad Co-Cu peak. The vibrating sample magnetometer measurements revealed that the saturation magnetization increases and coercivity decreases due to the decrease of the grain size caused by the increase of the Co content in the film. The structural and magnetic properties of Co-Cu films can be tailored, since these properties are directly related to the ratio of Co to Cu in the film.

The influence of saccharin on the electrodeposition and properties of Co–Ni alloy thin films

Transactions of the IMF, 2015

Co-Ni alloys thin films were electrodeposited on Ru substrates from a chloride-saccharin bath at pH 3.8 and the effects of adding saccharin to the bath on the electrochemical deposition, corrosion resistance, chemical composition, physical and magnetic properties of the deposits were investigated. The analytical techniques of cyclic voltammetry (CV), potentiodynamic polarisation, electrochemical impedance spectroscopy (EIS), atomic absorption spectroscopy (AAS), atomic force microscopy (AFM), X-ray diffraction and hysteresis curves were applied to assess the codeposition process, and determine corrosion resistance, composition, morphology, nanocrystallinity and magnetic properties. Effectively, CV measurements revealed that the addition of saccharin in the electrolytic bath modifies the deposition process and an anomalous codeposition takes place; this enhanced the Co percentage in the Co-Ni deposits. Saccharin addition also increases the double layer capacitance and decreases the charge transfer resistance. On the other hand, the Tafel plots show a higher corrosion resistance for the deposits obtained from a bath with saccharin than those obtained from a bath without it. Furthermore, the presence of the saccharin in the bath also causes notable changes in the morphology and structure characteristics of deposits. In addition, it was found that the additive influences the magnetic properties of Co-Ni alloy thin films. The coercivity and magnetisation saturation are diminished for Co-Ni films prepared from electrolytes with addition of saccharin.

Characterisations of CoCu films electrodeposited at different cathode potentials

Journal of Magnetism and Magnetic Materials, 2010

Structural and magnetic properties of CoCu films electrodeposited on polycrystalline Cu substrates were investigated as a function of cathode potential used for their deposition. The compositional analysis, performed by energy dispersive X-ray spectroscopy, demonstrated that an increase in the deposition potential results in an increase in Co content of CoCu films. The crystal structure of the films was studied using the X-ray diffraction (XRD) technique. It was observed that they have a face centred cubic (fcc) structure, but also contain partly hexagonal close-packed phase. XRD results revealed that the (1 1 1) peak of fcc structure splits into two as Co (1 1 1) and Cu (1 1 1) peaks and the peak intensities change depending on the deposition potential and hence the film composition. The magnetic measurements were carried out at room temperature using a vibrating sample magnetometer. The magnetic findings indicated that coercivity decreases and saturation magnetisation increases with the increase of Co:Cu ratio caused by the deposition potential and also all films have planar magnetisation.

Effect of pH on Composition, Structure and Magnetic Properties of Electrodeposited Co-Ni Alloys

Advanced Materials Research, 2009

Co-Ni alloy thin films were electrodeposited from sulfate baths at various solution pH values (1.5-5.5) ±0.1. The deposition kinetics of the films was studied using linear sweep voltametry (LSV). XRD studies exhibited fcc and hcp phases for Co-Ni alloys deposited at low and high pH ranges, respectively. EDAX studies showed that the cobalt content increased and nickel content decreased with increase in solution pH. The surface morphology of Co-Ni films were analyzed by scanning electron microscopy. It is found that the Co-Ni alloys synthesized at low pH exhibited soft magnetic properties and the films deposited at higher values revealed hard magnetic properties and the results are discussed.

Effect of film thickness on properties of electrodeposited Ni–Co films

Applied Surface Science, 2012

A series of Ni-Co films with different thicknesses was produced by using the electrodeposition technique and their microstructural, magnetic and magnetotransport properties were investigated. The X-ray (XRD) diffraction measurements showed that the films have the face centered cubic structure and the preferential orientations of the films were in the order of (1 1 1), (2 2 0) and (2 2 0) for the films with 1, 2 and 4 m thicknesses, respectively. The magnetic measurements revealed that the coercivity decreased from 52 Oe to 37 Oe due to the regular transition of preferential orientation from (1 1 1) to (2 2 0) with increasing film thickness. The study demonstrated that magnetic properties of the films changed according to the microstructural properties. Magnetoresistance investigations exhibited that all films have anisotropic magnetoresistance (AMR).