Nickel Thin Films Research Articles

Nano-indentation and nano-scratching of pure nickel and NiTi shape memory alloy thin films: an atomic-scale simulation

Issues with contact and friction in thin-film devices are inevitable in the field of micro-engineering, especially in micro-electro-mechanical systems (MEMS). In this study, the nano-indentation and nano-scratching behaviours of pure nickel and NiTi shape memory alloy (SMA) nano-films, two common materials used in MEMS, were comparatively investigated using large-scale molecular dynamics simulations. For the nickel nano-film structure, the load–displacement (P–h) curve demonstrated distinct elasto-plastic characteristics, and visible permanent deformation remained after unloading. In contrast, for the NiTi SMA, the P–h curve formed a hysteresis loop, and no evident deformation remained on the surface after unloading. It is noteworthy that during scratching, despite a lower applied normal pressure on the nickel nano-film than on the NiTi SMA, the friction and friction coefficient of the former were much higher. These differences in performance are closely related to the super-elasticity induced by the martensitic transformation within the NiTi SMA.

LAMMPS molecular dynamics simulation of methane decomposition on nickel thin films at high temperatures

The activation energy of methane decomposition by nickel was calculated using models of nickel thin films, a large-scale atomic/molecular massively parallel simulator (LAMMPS) and a ReaxFF potential. The rate constants of the first-order chemical reaction of methane decomposition were obtained by analyzing the number of undecomposed methane molecules in individual movie frames. The obtained activation energies of methane decomposition on the Ni (111) surfaces showed values close to those reported in the literature. The structural change of a Ni thin film with (111) surfaces was simulated to investigate how carbon and hydrogen atoms are deposited on the Ni thin film upon the decomposition of methane molecules at a high temperature. The catalytic activity of the (111) Ni thin film was found to decrease from the time point of critical supersaturation of carbon in the Ni thin film.

Nitrogen-doped graphene on a curved nickel surface

Graphene growth and doping are well studied on flat surfaces of various materials. To further advance the technological implementation of graphene-based systems, fundamental studies need more appropriate model templates, whose surfaces would mimic substrates with non-trivial topography. Here, using electron and photoelectron diffraction and photoemission spectroscopy as well, we demonstrate how a curved tungsten crystal covered by a thin nickel film can properly be used as such platform, allowing the fabrication and comprehensive characterization of nitrogen-doped graphene. We show the way in which nitrogen impurities prefer to embed into the graphene matrix at different areas of the curved metallic surface with variable density of atomic steps. In particular, at atomically flat regions with a strong graphene-metal interaction, pyridinic configuration is the most abundant form of dopants, while graphitic nitrogen strongly dominates in places with a weak coupling of graphene to the substrate, i.e., in the vicinity of the surface irregularities. We recognize single crystals with curvilinear surfaces as versatile platforms for the studies of not only low-dimensional materials, but also molecular adsorption, chemical reactions and catalysis on surfaces with complex structure.

Combined effect of mass and stiffness on the dynamics of a double-layered microcantilever

The combined effect of the mass and stiffness on a double-layered microcantilever has been studied. The resonance frequency of a silicon microcantilever with thin nickel film deposited on top is monitored as a function of the film thickness and examined based on a bi-layer cantilever model. These reveal that both mass and stiffness of the top layer on the cantilever structure affect the rate of the frequency change and the approximated expression for the thickness, where the frequency change deviates from the linear response, is presented, which would help to understand its dynamics upon the continuous accumulation of top layer.

Structural, magnetic and electrical properties of nickelthin films deposited on Si (100) substrates by pulsed laser deposition

Nickel thin films have been deposited on silicon (100) substrates by pulsed laser deposition at various substrate temperatures, Ts , in the range 100 - 700 ºC. X-ray diffraction analysis confirms nickel phases are present for Ts in the range 100 - 300 ºC, while above 500 ºC Ni-Si phases were observed. The grain size and roughness of thin films were in the range 30 nm - 590 nm and 4.3 - 15.7 nm respectively for thickness of the films is in the range 45 nm - 100 nm. Systematic variation with Ts was found for these morphological parameters, as well as the ratio of the remnant to saturation magnetic moment, magnetic coercivity and magnetoresistance.

Effects of Current Density on Surface Morphology and Coating Thickness of Nickel Plating on Copper Surface

Nickel (Ni) thin film was deposited on commercial pure copper using electrodeposition method. To understand the growth behavior of Ni nodules, deposition was done by varying the coating current density. The topography of coating was analyzed using Scanning Electron Microscope (SEM). The coatings were also analyzed for variation in amount of coating, cathode current efficiency and thickness of coating. The deposited Ni thin film was observed to be of coffee bean kind of secondary nodules with size varying from 400 to 800 nm and almost spherical primary nodules with size varying from 100 to 250 nm varying as a function of coating current density. At higher current density, the coatings were observed to be of multiple layers of nodules. This suggests the presence of defects like twins, dislocations and stacking faults. The nodules are observed to have fine crystallites in the nano range.

Benchmarking of oxygen evolution catalysts on porous nickel supports

Summary Active and inexpensive oxygen evolution reaction (OER) electrocatalysts are needed for energy-efficient electrolysis applications. Objective comparison between OER catalysts has been blurred by the use of different supports and methods to evaluate performance. Here, we selected nine highly active transition-metal-based catalysts and described their synthesis, using a porous nickel foam and a new Ni-based dendritic material as the supports. We designed a standardized protocol to characterize and compare the catalysts in terms of structure, activity, density of active sites, and stability. NiFeSe- and CoFeSe-derived oxides showed the highest activities on our dendritic support, with low overpotentials of η100 ≈ 247 mV at 100 mA cm–2 in 1 M KOH. Stability evaluation showed no surface leaching for 8 h of electrolysis. This work highlights the most active anode materials and provides an easy way to increase the geometric current density of a catalyst by tuning the porosity of its support.

Symmetry of the Magnetoelastic Interaction of Rayleigh and Shear Horizontal Magnetoacoustic Waves in Nickel Thin Films on LiTaO3

We study the interaction of Rayleigh and shear horizontal surface acoustic waves (SAWs) with spin waves in thin Ni films on a piezoelectric LiTaO$_3$ substrate, which supports both SAW modes simultaneously. Because Rayleigh and shear horizontal modes induce different strain components in the Ni thin films, the symmetries of the magnetoelastic driving fields, of the magnetoelastic response, and of the transmission nonreciprocity differ for both SAW modes. Our experimental findings are well explained by a theoretical model based on a modified Landau--Lifshitz--Gilbert approach. We show that the symmetries of the magnetoelastic response driven by Rayleigh- and shear horizontal SAWs complement each other, which makes it possible to excite spin waves for any relative orientation of magnetization and SAW propagation direction and, moreover, can be utilized to characterize surface strain components of unknown acoustic wave modes.

Spectral Characteristics of an Oblique-Incidence Reflection Interferometer as a Refractive Index Sensor

A sensor of refractive index of analytical liquid operating in the Kretschmann geometry and based on an oblique-incidence reflection interferometer (RI) is simulated for the first time, and its spectral properties are investigated. The principle of operation of the sensor is based on the effect of inverted surface plasmon resonance (ISPR). The sensitive structure represents the metal–dielectric multilayer coating consisting of thin nickel film in combination with quarter-wave dielectric layers. Simulation of the principle of RI fabrication under oblique incidence of light is described. Expressions governing sensitivity, spectral width of the ISPR-induced maximum in reflection, along with the figure of merit, are derived. It is demonstrated that this type of sensor can exhibit extremely high values of the figure of merit (>103) due to high Q factor.

Effect of Ni doping on optical, structural, and morphological properties of ZnO thin films synthesized by MSILAR: Experimental and DFT study

In this study the thin films of Zinc Oxide (ZnO) and Nickel (Ni) doped ZnO were successfully synthesized by the simple modified successive ion layer adsorption and reaction method, with 30 cycles of dipping a substrate directly in cationic and anionic precursors without rinsing in water. The effect of nickel doping with this method was investigated. The X-ray diffraction (XRD) analysis confirms the wurtzite structure of ZnO in the thin films, without any secondary phases. A decrease in grain size and cell parameters was observed. Scanning electron microscopy (SEM) with energy dispersive X-Ray (EDX) analysis showed that Ni significantly affects the morphology of thin films. UV-visible spectra are obtained in the wavelength range between 300 nm to 1100 nm. A decrease in band gap from 3.23 eV to 3.11 eV was observed. First principal calculation was used to reveal the effect of Ni on electronic and magnetic properties. It showed that ZnO and Ni doped ZnO exhibits a direct band gap semiconductor and Ni-3d electrons are the primary source of magnetic momentum in ZnO matrix.

Study of Methanol Electro-Oxidation on Thin Nickel Films by Sampled Current Voltammetry

Nickel-based electrocatalysts have shown good catalytic activity for the electrochemical oxidation of alcohols in alkaline media, which has generated significant interest in using nickel films and nickel oxides in alcohol fuel cells. In this work, Ni films were deposited by the galvanostatic method on gold electrodes. The electrocatalytic activity for the electro-oxidation of methanol from these deposits was evaluated by cyclic voltammetry (CV) and sampled current voltammetry (SCV). Cyclic voltammetry measurements showed that depending on the Au electrode roughness, the position NiOOH formation peak of the electrodeposited Ni deposits could differ. The deposits were divided depending on whether the NiOOH formation peak was below or above 0.39 V vs. Ag|AgCl reference electrode. Sampled current voltammograms showed that the former presented greater specificity for the oxidation of methanol, and the latter, showed electrocatalytic activity for both the oxidation of methanol and for the oxygen evolution reaction.

Nickel thin film preparation and its characterization as catalyst for HWC-in plasma-PECVD-growth graphene

Nickel thin film, aimed at catalyst layer for HWC-in plasma-PECVD-growth of graphene, has been deposited on SiO2 glass of microscope slide by thermal evaporation method. The thickness of the as-deposited Ni films was not uniform ranging from 200 nm to 700 nm as revealed from cross sectional SEM image. To reduce the film thickness and improve the crystal quality of the films, the samples were annealed in the furnace with three different temperatures, T = 400 °C, 500 °C, and 600 °C, for three hours. SEM images of the post-treatment indicated that the film thickness decreased to about 100–200 nm after annealed at 500 °C for 3 h. Increasing the annealing temperature to 600 °C leads the nickel atoms out of the substrate so that it leaves the substrate without nickel thin film anymore. The disappearing of the Nickel film after annealing at temperature 600 °C was confirmed by EDS spectrum examination which showed that there was no nickel element in the sample. Due to the loss of nickel thin film after annealing at 600 °C, we set the annealing temperature at 500 °C and optimized duration of annealing. It was found that after annealing for 4 h the obtained thickness of thin film was averagely 44 ± 6 nm with some spread piles on the film. Increasing annealing duration to 5 h lead to increasing the thickness of thin film nickel to be 66 ± 14 nm which seems contradict with our expectation. However, the tens order magnitude of thin film thickness obtained is the expected result for graphene growth.

Спектральные характеристики наклонного отражательного интерферометра как сенсора показателя преломления

The paper presents simulation of the refractive index sensor of the analyzed liquid in the Kretschmann configuration based on an oblique reflective interferometer (RI) and its spectral properties for the first time. The principle of operation of this sensor is based on the effect of inverted surface plasmon resonance (ISPR). The sensitive structure is the metal-dielectric multilayer coating based on a nickel thin film in combination with non-quartewavelength dielectric layers. Modeling of the RI manufacturing process under oblique light incidence is described. Formulas for estimating the sensitivity and spectral width of the reflection maximum of ISPR are given, as well as the figure of merit. It is shown that due to the high quality factor, this type of sensor can have very large figure of merit (>10^3).

Optical properties of zigzag nickel nanostructures obtained at different deposition angles

In this study, nickel (Ni) thin films were deposited at two different angles (65o and 85o) using Glancing Angle Deposition technique, to the thicknesses of 60 - 290 nm. Structural analysis of the deposited films was performed by scanning electron microscopy and X-ray diffraction, while spectroscopic ellipsometry was used for the investigation of optical properties. Electrical resitivity of the samples was determined by four-point probe method. Structural analysis showed that the Ni films grow in a shape of zigzag nanocolumns, where the deposition angle strongly affects their porosity. As the thickness of the films increase they absorb light strongly and become less dense. Besides, samples deposited at the angle of 85o exhibit higher values of electrical resistivity as compared to the samples deposited at the angle of 65o, which can be correlated with high porosity and the growth mechanism of the deposited nanostructures.

Statistical analysis of electrodeposited nickel coating to S275JR grade mild steel

In recent trends the electrodeposition process are very important of the soft material as well as hard material to avoid the corrosion resistance. For this research, S275JR mild steel specimens are considered as a base material for the coating A thin film Nickel coatings are made on the S275JR mild steel with the concentration of electrodepositing route. Due to this electrodeposition work modified the surface structure, improves the mechanical properties and turned to high corrosion resistance in nature. Three process parameters are considered for this work namely: voltage rate, stirring speed and time. The response values of micro hardness and mass of deposition are analyzed by L9 orthogonal array effectively. Enhanced micro hardness and mass of deposition of S275JR mild steel is obtained by the influence of two major parameters such as time period and the stirring speed. Rank order and delta values are point out the parameters precedence. ANOVA statistical approaches informed the process factors role and contribution effectively.

Control of porosity and optical properties of slanted columnar Ni thin films

Abstract In this work we deposited nickel thin films by Glancing Angle Deposition at two different angles (65° and 85°) onto glass substrates. The structure of the films, thicknesses between 50 and 200 nm, was studied by scanning electron microscopy, atomic force microscopy and X-ray diffraction, while the chemical properties were analyzed using X-ray photoelectron spectroscopy. According to the obtained results it can be seen that the deposition angle has influence on porosity, crystallinity and surface roughness. Optical properties were investigated by spectroscopic ellipsometry and electrical properties were measured by four point probe. Spectroscopic ellipsometry revealed that the refractive index and extinction coefficient varied with thickness and deposition angle, which can be correlated with changes in microstructure and porosity of Ni films. The observed variations in resistivity could be attributed to the changes in the width of the columns, as well as to the amount of oxide present in the samples.

Role of substrate on film thickness, structural, compositional and magnetic properties of CoNi alloy thin films by low temperature electrodeposition technique

Impressment of Cobalt and Nickel based alloys in industries for the last few years attracted many researchers due to its significant features of physical, chemical and magnetic properties. The present work focused the structural, compositional, morphological and magnetic properties of Cobalt Nickel alloy thin film growth by one of the chemical methods. Thin films of Cobalt Nickel have been deposited on various substrates by means of low cost galvanostatic electrodeposition technique. Structural investigation showed that the deposited films have face centred cubic structure with orientation of crystallites along (111) plane. The structural parameters such as crystallite size, rms microstrain, dislocation density and stacking fault probability are estimated for the deposited films. Morphological features along with film composition showed that the deposited films have smooth surface with stoichiometry. Magnetic properties such as coercivity, remanence, retentivity was estimated and the results are reported.

Nondestructive Femtosecond Laser Lithography of Ni Nanocavities by Controlled Thermo-Mechanical Spallation at the Nanoscale.

We present a new approach to femtosecond direct laser writing lithography to pattern nanocavities in ferromagnetic thin films. To demonstrate the concept, we irradiated 300 nm thin nickel films by single intense femtosecond laser pulses through glass substrate. Using a fluence above the ablation threshold, the process is destructive, leading to the formation of an ablation crater. By progressively lowering the laser fluence, the formation of closed spallation cavities below the ablation threshold is achieved. Systematic studies by the electron and optical interferometric microscopies, supported by molecular dynamics simulations, enabled us to gain an understanding of the thermo-mechanical spallation mechanism at the solid-molten interface. We achieved the fabrication of periodic arrangements of closed spallation nanocavities. Due to their topology, closed magnetic nanocavities can support unique couplings of multiple excitations (magnetic, optical, acoustic, spintronic). Thereby, they offer a unique physics playground for emerging fields in magnetism, magneto-photonic, and magneto-acoustic applications.

Structural and optoelectronic properties of epitaxial Ni-substituted Cr2O3 thin films for p-type TCO applications

Transparent and conducting epitaxial thin films of pristine chromium oxide (Cr2O3) and nickel (Ni) substituted Cr2O3 were deposited on the sapphire substrates using pulsed laser deposition (PLD) technique. Co-precipitation method was used to prepare targets of Cr2O3 nanomaterials with varying Ni content (i.e. x = 0, 0.03, 0.05 and 0.1). In-plane diffraction (i.e. ϕ-scan) measurements confirmed that all thin films were epitaxially grown on sapphire substrates. X-ray diffraction (XRD) patterns illustrated that all thin films orienting along (006) plane only and crystallize in the rhombohedral structure of Cr2O3, and structure remains unchanged with Ni-substitution. Consequently, Cr cations were replaced by Ni counter-cations in Cr2O3 structure, which lead to the delocalization of holes and improve mobility. Moreover, an increase in Ni-content also leads to upsurge in the carrier concentration. Hence, both factors contributed to the improvement in Ni-substituted Cr2O3 thin films' conductivity and retained the p-type character as well. UV–Vis spectra demonstrated that pristine Cr2O3 thin film acquired an optical band gap energy of 3.64 eV, decreasing to 3.48 eV with Ni-substitution. Furthermore, optical transmittance spectra illustrated the average transparency of 77–81% for as-deposited thin films in the visible region. Therefore, this material can render a wide variety of applications in the field of optoelectronics.

Observation of ion acceleration in nanosecond laser generated plasma on a nickel thin film under rear ablation geometry.

In this article we report acceleration observed for the ions produced in a 50-nm-thick nickel film coated on a quartz substrate, under nanosecond laser ablation, in the rear ablation geometry. A detailed study with varying background pressure and laser energy is done. Spectroscopic study including spectroscopic time of flight (STOF) measurements of ionic and other neutral transitions from the plasma has been undertaken. The STOF spectra recorded for ionic transition clearly show an enhancement in the velocity of the slow component as the background pressure increases. In addition, a large asymmetric spectral broadening in the 712.22-nm neutral line is observed, which increases with background pressure. While these observations have similarity to some of the reported studies on the acceleration of ionic species through double-layer formation, the electric fields calculated from the measured acceleration appear to be anomalously higher, and a double-layer concept seems to be inadequate. Moreover, the large asymmetry observed in the neutral line profile is indicative of microelectric fields present inside the laser produced plasma plume, which may play a role in the continuous acceleration of the ions. Interestingly, this asymmetry in spectral broadening exhibits temporal and spatial dependence, which indicates that significant electric field is present in the plasma plume even for longer duration and larger distance from the target. These spectroscopic observations of acceleration have also been complemented by triple Langmuir probe measurements. To the best of our information, such observations regarding large ion acceleration for the rather low laser intensities as used in this experiment have not been reported in literature so far.