Simultaneous Co-deposition Research Articles

Free-standing polyaniline-reduced graphene oxide (PANI-rGO) thermoelectric films via electrochemical synthesis

Abstract Heat-based energy harvesting is gaining attention as an alternative energy source. Thermoelectric materials (TEs) generate voltages in response to a thermal gradient and conductive polymer-carbon composites have properties that make them favorable for these applications. Polyaniline-reduced graphene oxide (PANi-GO) thermoelectric thin films were fabricated by the electropolymerization of PANi with simultaneous co-deposition of graphene onto fluorine-doped tin oxide (FTO). Poly(butyl acrylate) was spin-coated onto these films as backing support to make a stable free-standing film of PANi-rGO. The free-standing film was formed upon GO reduction which resulted in simultaneous delamination from the FTO electrode. Compositional and morphological data were obtained via Raman microspectroscopy and scanning electron microscopy and the TE properties were measured in terms of the Seebeck coefficient and conductivities from Hall effect measurements. The Seebeck coefficients of the films measured between 6.6 μV K−1 to 13.4 μV K−1, whereas Hall effect conductivities ranged from 0.483 to 2.68 S cm−1. The highest film power factor measured was 0.025 μW m−1K−2. Varying the GO content used in the electropolymerized film did not have a significant effect on the overall TE property though varying the reduction cycle number and voltage resulted in significant changes in the film Seebeck coefficients and conductivities.

Physicochemical, Morphological and Anticorrosive Properties of Electrodeposited ZnNi Alloy Coating

Corrosion in its many forms is a major problem for many types of materials, extending from machining to manufacturing and daily use. In fact, it affects practically all engineering projects, from the biggest to the smallest: energy production, construction, transport, medical sector, electronics, etc. Consequently, corrosion generates both economic and environmental problems. To prevent corrosion and preserve materials' durability, several protection methods can be applied. These included protection by applying a coating on the metal surface. In this context, Zinc based alloy coatings have attracted much interesting scientific community because of their excellent mechanical and anti-corrosive properties. In the present work, ZnNi coatings were electrodeposited on steel substrates using a chloride bath containing ammonium salts. The effect of some experimental parameters, namely, potential and metal ion concentration ratio on the deposition kinetics of ZnNi system as well as on its physicochemical, morphological and anticorrosive properties has been investigated. For this purpose, an appropriate experimental work was performed by using both electrochemical (cyclic voltammetry, chronoamperometry, open circuit potential, potentiodynamic polarization) and nonelectrochemical (SEM-EDX) analysis methods. Based on the obtained results, it has been revealed that simultaneous codeposition of both elements Zn and Ni is possible in our experimental conditions. However, deposition kinetics exhibited a strong dependence on explored parameters. Also, morphological aspect and chemical composition of deposits are strongly influenced by metal ion concentration ratio. Investigation of corrosion behaviour confirms the protective effect of coatings acted as a sacrificial anode. Furthermore, increasing Ni content in the deposits induces a significant enhancement in corrosion resistance. Thus, Zn-Ni alloy coatings prepared from the Ni(II)-rich bath exhibited better corrosion resistance.

Enhancing Efficiency of Large-Area Wide-Bandgap Perovskite Solar Modules with Spontaneously Formed Self-Assembled Monolayer Interfaces.

Wide-bandgap (WBG) perovskites play a crucial role in perovskite-based tandem cells. Despite recent advances using self-assembled monolayers (SAMs) to facilitate efficiency breakthroughs, achieving precise control over the deposition of such ultrathin layers remains a significant challenge for large-scale fabrication of WBG perovskite and, consequently, for the tandem modules. To address these challenges, we propose a facile method that integrates MeO-2PACz and Me-4PACz in optimal proportions (Mixed SAMs) into the perovskite precursor solution, enabling the simultaneous codeposition of WBG perovskite and SAMs. This technique promotes the spontaneous formation of charge-selective contacts while reducing defect densities by coordinating phosphonic acid groups with the unbonded Pb2+ ions at the bottom interface. The resulting WBG perovskite solar cells (PSCs) demonstrated a power conversion efficiency of 19.31% for small-area devices (0.0585 cm2) and 17.63% for large-area modules (19.34 cm2), highlighting the potential of this codeposition strategy for fabricating high-performance, large-area WBG PSCs with enhanced reproducibility. These findings offer valuable insights for advancing WBG PSCs and the scalable fabrication of modules.

Low-energy ion beam erosion of Si with simultaneous co-deposition of metallic surfactants: Experimental and simulated data

Ion beam erosion of Si under co-deposition circumstances supports the formation of surface patterns on the nano- and micrometer scale. To evaluate the effect of surfactant sputtering within a setup relevant for ultra precision surface finishing, this work is presented. We present data for samples prepared with Ar ion beam erosion, at low ion energy. Al, Cu, steel, Cr, Ni, Mo, Ti, Ta, Zn and Si were chosen as co-deposition material. Simultaneous irradiation of the co-deposition material and the Si samples were performed with a broad beam ion source. The structuring and pattern formation are discussed with SEM and AFM measurements. It was shown that the evolution of structures on the substrate is induced by the silicide-forming metals. This corresponds with a higher surface roughness. Whereas the non-silicide-forming metals did not show patterning, and accordingly, lower surface roughness. Measurements regarding the Si removal rate showed, that it depends on the co-deposition material. Supporting simulation data proposed that the effect of the co-deposition material on the Si removal is determined by the combination of sputtering and scattering properties of the co-deposition material. The ratio of scattered Ar ions to sputtered metal particles describes the effect on the removal change. For metals which tend to higher scattering, the removal is enhanced. This applies for most of the metals with higher atomic number. Whereas the metals with lower atomic number favor self-sputtering, which results in an decreased Si removal.

Plasmonic Ag/Cu/PEG nanofluids prepared when solids meet liquids in the gas phase.

Since the time of Faraday's experiments, the optical response of plasmonic nanofluids has been tailored by the shape, size, concentration, and material of nanoparticles (NPs), or by mixing different types of NPs. To date, water-based liquids have been the most extensively investigated host media, while polymers, such as poly(ethylene glycol) (PEG), have frequently been added to introduce repulsive steric interactions and protect NPs from agglomeration. Here, we introduce an inverse system of non-aqueous nanofluids, in which Ag and Cu NPs are dispersed in PEG (400 g mol-1), with no solvents or chemicals involved. Our single-step approach comprises the synthesis of metal NPs in the gas phase using sputtering-based gas aggregation cluster sources, gas flow transport of NPs, and their deposition (optionally simultaneous) on the PEG surface. Using computational fluid dynamics simulations, we show that NPs diffuse into PEG at an average velocity of the diffusion front of the order of μm s-1, which is sufficient for efficient loading of the entire polymer bulk. We synthesize yellow Ag/PEG, green Cu/PEG, and blue Ag/Cu/PEG nanofluids, in which the color is given by the position of the plasmon resonance. NPs are prone to partial agglomeration and sedimentation, with a slower kinetics for Cu. Density functional theory calculations combined with UV-vis data and zeta-potential measurements prove that the surface oxidation to Cu2O and stronger electrostatic repulsion are responsible for the higher stability of Cu NPs. Adopting the De Gennes formalism, we estimate that PEG molecules adsorb on the NP surface in mushroom coordination, with the thickness of the adsorbed layer L < 1.4 nm, grafting density σ < 0.20, and the average distance between the grafted chains D > 0.8 nm. Such values provide sufficient steric barriers to retard, but not completely prevent, agglomeration. Overall, our approach offers an excellent platform for fundamental research on non-aqueous nanofluids, with metal-polymer and metal-metal interactions unperturbed by the presence of solvents or chemical residues.

Rapid and label-free Listeria monocytogenes detection based on stimuli-responsive alginate-platinum thiomer nanobrushes.

In this work, we demonstrate the development of a rapid and label-free electrochemical biosensor to detect Listeria monocytogenes using a novel stimulus-response thiomer nanobrush material. Nanobrushes were developed via one-step simultaneous co-deposition of nanoplatinum (Pt) and alginate thiomers (ALG-thiomer). ALG-thiomer/Pt nanobrush platform significantly increased the average electroactive surface area of electrodes by 7 folds and maintained the actuation properties (pH-stimulated osmotic swelling) of the alginate. Dielectric behavior during brush actuation was characterized with positively, neutral, and negatively charged redox probes above and below the isoelectric point of alginate, indicating ALG-thiomer surface charge plays an important role in signal acquisition. The ALG-thiomer platform was biofunctionalized with an aptamer selective for the internalin A protein on Listeria for biosensing applications. Aptamer loading was optimized and various cell capture strategies were investigated (brush extended versus collapsed). Maximum cell capture occurs when the ALG-thiomer/aptamer is in the extended conformation (pH > 3.5), followed by impedance measurement in the collapsed conformation (pH < 3.5). Low concentrations of bacteria (5CFUmL-1) were sensed from a complex food matrix (chicken broth) and selectivity testing against other Gram-positive bacteria (Staphylococcus aureus) indicate the aptamer affinity is maintained, even at these pH values. The new hybrid soft material is among the most efficient and fastest (17min) for L. monocytogenes biosensing to date, and does not require sample pretreatment, constituting a promising new material platform for sensing small molecules or cells.

Gradient magnetron co-sputtered μ m-thick Al–Si films on dielectric substrates for operation in the millimeter-wave band

Ongoing active development of modern radio frequency electronic devices operating in the millimeter (V) band, such as fifth-generation wireless communications, demands new materials to control electromagnetic interference, compatibility, and reliability of such systems. This work investigates feasibility absorptive non-reflective thin coatings deposition on dielectric substrates using simultaneous magnetron co-deposition. For this, electromagnetic waves propagation in the millimeter band through in micrometer-thick Al–Si films of varied composition was studied. The co-deposition process was controlled by the ratio of sputtered atoms fluxes. Graded segregation was observed under certain parameters of the co-deposition process, resulting in a depth gradient of an aluminum content, as confirmed by the secondary ion mass spectrometry study. A qualitative model was proposed involving aluminum-induced silicon recrystallization happening in the course of a known aluminum interlayer exchange process. The observed Al–Si segregation effect in micrometer-thick films allows for preparation of the non-reflective and absorptive material for operation in the V-band with reflection losses more than 10 dB and transmission losses around 5 dB in the bandwidth of up to 20 GHz.

Amorphous Framework in Electrodeposited CuBiTe Thermoelectric Thin Films with High Room-Temperature Performance.

Bismuth telluride-based alloys are the most efficient thermoelectric materials near room temperature and widely used in commercial thermoelectric devices. Nevertheless, their thermoelectric performance needs to be improved further for wide-scale implementation either as a thermoelectric generator or cooler. Here, we propose a simultaneous codeposition of CuBiTe thin films and their phase transition strategy via the traditional electrodeposition process. With just 13 atom % Cu doping, crystalline-to-amorphous phase transformation resulted for the electroplated CuBiTe alloy. A close look at the alloy composition revealed spike-shaped nanocrystalline Bi2Te3 embedded in the CuBiTe amorphous matrix. Our result shows an exceptionally high power factor (3.02 mW m–1 K–2), which comes from the enhanced Seebeck coefficient (−275 μV K–1) and high electrical conductivity (3.99 × 104 S m–1) of CuBiTe films. Therefore, it can be suggested that the adopted strategy to form a unique nanocrystallite-embedded amorphous framework provides a platform to develop next-generation high-performance thermoelectric materials with an extraordinary power factor.

Gallium-Enhanced Aluminum and Copper Electromigration Performance for Flexible Electronics.

Wide range binary and ternary thin film combinatorial libraries mixing Al, Cu, and Ga were screened for identifying alloys with enhanced ability to withstand electromigration. Bidimensional test wires were obtained by lithographically patterning the substrates before simultaneous vacuum co-deposition from independent sources. Current–voltage measurement automation allowed for high throughput experimentation, revealing the maximum current density and voltage at the electrical failure threshold for each alloy. The grain boundary dynamic during electromigration is attributed to the resultant between the force corresponding to the electron flux density and the one corresponding to the atomic concentration gradient perpendicular to the current flow direction. The screening identifies Al-8 at. % Ga and Cu-5 at. % Ga for replacing pure Al or Cu connecting lines in high current/power electronics. Both alloys were deposited on polyethylene naphthalate (PEN) flexible substrates. The film adhesion to PEN is enhanced by alloying Al or Cu with Ga. Electrical testing demonstrated that Al-8 at. % Ga is more suitable for conducting lines in flexible electronics, showing an almost 50% increase in electromigration suppression when compared to pure Al. Moreover, Cu-5 at. % Ga showed superior properties as compared to pure Cu on both SiO2 and PEN substrates, where more than 100% increase in maximum current density was identified.

Self-assembled Co(OH)2/functionalized MWNTs/porous graphene ternary binder-free hybrid for supercapacitors

Here, cobalt hydroxide/porous graphene/functionalized MWNTs three-component nano-hybrid is electrochemically co-implanted onto Ni foam and its supercapacitive capability is compared with the pristine Co(OH)2/Ni electrode prepared through the similar method. The functionalized multi-walled nanotubes and porous graphene (f-MWNTs-PG) composite is first prepared through hydrothermal method. Then, the simultaneous co-deposition of Co(OH)2/f-MWNTs-PG hybrid is achieved from f-MWNTs-PG dispersed 10 mM Co(NO3)2 aqueous bath. The characterization results showed a uniform growth of β-Co(OH)2 platelets onto the f-MWNTs-PG electrophoretically implanted onto the Ni foam. An enhanced surface area of 304.4 m2/g with mesoporous texture was observed for the hybrid material, where pristine Co(OH)2 had surface area of 234.55 m2/g. Co(OH)2@f-MWNTs-PG/Ni hybrid exhibited an excellent capacitive behavior, i.e., specific capacitances as high as 1426 and 1075 F/g at 1 and 10 A/g, and low capacity losses of 5.9% and 10.5% after 6000 cycling at 1 and 3 A/g, respectively. However, the Co(OH)2/Ni showed low capacitance values of 1029 and 544 F/g at 1 and 10 A/g, and also high losses of 15.6% and 43.5% at the current loads of 1 and 3 A/g, respectively. The improved performance of hybrid electrode was ascribed to the synergetic effects between f-MWNTs/PG and hydroxide platelets in the composite form.

Dual-functioning porous catalysts: robust electro-oxidation of small organic molecules and water electrolysis using bimetallic Ni/Cu foams

The simultaneous co-deposition of Cu within the matrix of Ni foams (utilizing DHBT) increases their intrinsic catalytic activity towards water electrolysis, urea oxidation reaction (UOR), and glycerol oxidation reaction (GOR) in alkaline media.

Structural Properties of Fe3Si thin Films at Different Pulsed-Laser-Deposition Modes

The formation and investigation of Fe3Si thin films by pulsed laser deposition is reported. The structural properties depending on the formation parameters are investigated. Three different approaches to the synthesis of iron-silicide thin films by pulsed laser deposition are explored: deposition from a stoichiometric alloy target, the simultaneous co-deposition of pure Fe and Si targets by two lasers and the single-laser cyclic co-deposition of pure targets.

Efficient electro-catalytic oxidation of ethylene glycol using flower-like graphitic carbon nitride/iron oxide/palladium nanocomposite for fuel cell application

The design and development of highly efficient and environmental-friendly methods for the synthesis of electro-catalysts are highly significant for fuel cell applications. Herein, we demonstrate a facile technique for the synthesis of graphitic carbon nitride/iron oxide/palladium nanoparticles (g-C3N4/Fe2O3/PdNPs) composite towards efficient electro-catalytic oxidation of ethylene glycol. g-C3N4/Fe2O3/PdNPs nanocomposite was prepared using a one-step simultaneous electrochemical co-deposition process. The electro-deposition was performed on a single-disk carbon screen-printed electrode (SPE) under acidic electrolyte solution containing g-C3N4 nanosheets, Fe2O3 nanoparticles, and palladium chloride as precursors. The structural and elemental composition of the electrochemically fabricated g-C3N4/Fe2O3/PdNPs nanocomposites modified SPE was investigated using fourier-transform infrared spectroscopy, field-emission scanning electron microscopy, and X-ray photoelectron spectroscopy techniques and the results indicated that three-dimensional nanoflower-like Fe2O3 and spherical shaped PdNPs were electro-deposited on the g-C3N4 nanosheets to form the nanocomposite. The voltammetric behavior of the developed g-C3N4/Fe2O3/PdNPs/SPE showed excellent electro-catalytic response towards ethylene glycol and superior electro-oxidation with high durability when compared to commercial Pd/C and other recently reported electro-catalyst materials. Therefore, the proposed g-C3N4/Fe2O3/PdNPs nanocomposite is proved to be an efficient electro-catalyst and can be highly suitable for direct alcohol fuel cell applications.

The Powder Aerosol Deposition Method - Making Ceramic Gas Sensor Films at Room Temperature

Introduction Most gas sensors are ceramic devices. They are manufactured in ceramic techniques like tape technology and/or conventional thick-film techniques (typically screen-printing with subsequent firing) [1]. During firing, between substrate and gas sensitive film interdiffusion processes occur. They may (at least partly) deteriorate the gas sensing properties of the functional oxides. Some materials can even hardly be processed without decomposition. Therefore, room temperature deposition techniques may be advantageous. The Powder Aerosol Deposition Method The Powder Aerosol Deposition Method (PAD) bases on a film densification mechanism called Room Temperature Impact Consolidation (RTIC). This allows producing dense ceramic films without any high-temperature processes directly from an initial ceramic powder on almost any substrate material. This contribution gives examples for PAD-applications in the field of gas sensing.The results are very promising, despite the process is rather simple. Driven by a pressure difference to a vacuum deposition chamber (evacuated only to a rough vacuum), the aerosol is accelerated by a slit nozzle to several hundred m/s. This aerosol jet ejects particles into the deposition chamber. Here, the particles impact on a movable substrate and get fractured into nanometer-sized fragments that are compacted by subsequently impacting particles. Fig. 1 depicts the basic principle. Further process details can be found in the reviews [2], [3], or [4]. Results and Discussion Some examples for PAD-based sensors are surveyed here. Besides conventional conductometric gas sensors based on SnO2 and other metal oxides to detect limited gaseous components, applications for temperature independent oxygen sensors are reported, e.g. of SrTi1-x Fe x O3 [5], [6] or BaFe1-x Ta x O3 (BFTx) [7]. Simultaneous aerosol co-deposition of inert and functional oxides to fine-tune the sensing properties may be promising [6].Figure 2 is a measurement protocol at 900 °C of the logarithm of the film conductivity of BFAT30 fabricated by PAD. The material is rapidly and reproducibly responding to stepwise changes of the oxygen partial pressure, pO2. In Figure 3, the log-log plot of the conductivity (log s vs. log pO2) of the sensor between 600 °C and 900 °C in the pO2 range from 0.01 to 1 bar is shown. Neither the sensitivity to oxygen (slope in the log-log-plot) nor the base line resistance changes with temperature. Log s depends linearly on log pO2 between 700 °C and 900 °C, showing a slope of 0.24. An improved formulation contains 1 % alumina (BFATx). Amongst the BFATx samples examined, particularly good properties were found with regard to temperature independency for BFAT25 (BaFe0.74Al0.01Ta0.25O3).Combined resistive and thermoelectric oxygen sensors with almost temperature-independent characteristics of both conductivity and Seebeck coefficient were manufactured using BFAT30 [8].Classical tin-oxide conductometric metal oxide gas sensors were deposited by PAD at room temperature on interdigital electrodes. As expected, they show a pronounced sensitivity to nitrogen oxides at around 300 °C and to hydrogen at around 450 °C [9].With PAD, solid electrolyte electrochemical gas sensors have also been successfully manufactured [10]. A nitrogen oxide sensor using the novel pulsed-polarization method, which attracted much attention recently with YSZ as solid electrolyte, can now be operated at lower temperatures due to the use of a Bismuth-based fast oxide ion conductors (Fig. 4).The powder aerosol deposition method is also suitable to produce thermistors with a negative temperature coefficient of resistance (NTCR) [11]. They may serve as sensitive detectors for pellistors. Conclusions It is possible to manufacture ceramic gas sensor films completely without any high-temperature process and directly from an initial ceramic powder on almost any substrate material. Even temperature sensors can be realized. Future research directions may focus on sensors on polymers or textiles by applying the powder aerosol deposition method.

Copper-rich Cu–Zn alloy coatings prepared by electrodeposition from glutamate complex electrolyte: Morphology, structure, microhardness and electrochemical studies

In the present work, glutamate ions were applying as a complexing agent in codeposition of Cu-Zn alloy coatings from a non-cyanide acidic sulfate bath at room temperature. The effect of Cu2+/Zn2+ concentration ratios as well as the glutamate ion concentrations on the morphology, structure, and microhardness of the alloy coatings was studied. Electrochemical analyses were implemented using cyclic voltammetry and anodic linear stripping voltammetry. It was found that glutamate ions decrease cathodic overpotential for the reduction of Zn2+ ions and enhances cathodic overpotential for the reduction of Cu2+ ions. Consequently, the simultaneous codeposition of Zn2+ and Cu2+ ions were facilitated and copper-rich Cu–Zn alloy coating was achieved. Characterization of Cu-Zn alloy coatings was carried out using SEM and XRD. The Cu-Zn alloy deposited from the glutamate complex bath consisted mainly of one phase α-CuZn. The morphology of Cu-Zn alloy significantly depends on the Cu2+/Zn2+ concentration ratios, glutamate ion concentrations as well as on the operating conditions as shown by SEM investigation. Moreover, Cu-Zn alloy coating deposited from these baths possesses microhardness ranged from 115 to 250 kg mm−2 depending on the bath composition and the operating conditions.

Electrodeposition of Nanoparticles and Continuous Film of CdSe on n-Si (100).

CdSe electrodeposition on n-Si (100) substrate was investigated in sulfuric acid solution. The behaviour and the deposition of the precursors (Cd and Se) were studied separately at first. Then, we explored both the alternated deposition, one layer by one, as well as the simultaneous co-deposition of the two elements to form the CdSe semiconductor. Varying the deposition conditions, we were able to obtain nanoparticles, or a thin film, on the surface of the electrode. The samples were then characterised microscopically and spectroscopically with SEM, XRD and XPS. Finally, we evaluated the induced photoemission of the deposit for the application in optoelectronics.

(Invited) in-Vacuo Studies of MBE Grown Transition Metal Dichalcogenides

Here we present recent work on the synthesis and characterization of two-dimensional transition metal dichalcogenides (TMDs) grown by molecular beam epitaxy (MBE). Bulk TMD crystals consist of two-dimensional layers bonded together by van der Waal interactions; the lack of primary bonds at the TMD interface allow for the growth of TMD heterostructures on a variety of substrates without the need to consider lattice constant mismatch or crystal structure of the substrate which we aim to demonstrate. TMDs are grown and characterized in an all in-vacuo ultra-high vacuum system which enables the simultaneous co-deposition of multiple transition metals and chalcogens allowing for the study of TMD ternary alloys and layered heterostructures followed by their compositional and intrinsic electronic characterization prior to atmospheric exposure. Presented will be a review of our work studying the interface chemistry between TMD and conventional semiconducting substrates, as well as our investigations of 2D-2D heterostructure grown by MBE. Figure 1 shows an example of in-vacuo x-ray photoelectron spectroscopy (XPS) carried out on GaAs(001) before an after the growth of monolayer MoSe2. The sample was initial passivated by a sulfur based treatment, and the presence of sulfur bonded to the surface can be observed in the As 2p and Ga 2p spectra. The asymmetry observed in the As 2p and Ga 2p core-levels suggest that some reactions with Se take place during the growth. The thermal stability of this interface will be investigated using in-situ UHV heating and XPS. In separate work we evaluated the valence band offsets using in-vacuo XPS and UPS (ultraviolet photoelectron spectroscopy). This is achieved by measuring core-level to valence band maximum separation for control samples as well as the core-level shifts in heterostructure. In-vacuo XPS analysis can also be used to reveal any interface reactors that may occur between the TMDs. It is found that for chalcogen deficient growths, metallic signatures can be detected. Of particular interest is the process structure relationships. Presented will be parametric studies showing impact of growth temperature and relative metal-chalcogen flux ratios on the electronic structure and interface chemistry in both the 2D-2D and 2D-3D systems. The all in-vacuo synthesis and analysis cluster tool allows these investigations to be carried out without air exposure which can induce substantial changes in the chemistry of these materials. Figure 1

Terrace morphology on fused silica surfaces by Ar+ ion bombardment with Mo co-deposition

The morphology evolution of self-organized nanopatterns induced during Ar+ ion bombardment (IB) with Mo co-deposition on fused silica (SiO2) surfaces at different incidence angles and fluences was investigated by using atomic force microscopy and transmission electron microscopy. For pure IB at incidence angles from 30° to 70°, SiO2 surfaces evolve from being flat, via ripples, to direction-transversed ripples. In contrast, at the same ion fluence and incidence angles, the simultaneous Mo co-deposition leads to significant terraced structures with significantly enhanced roughness and wavelength. Our observations show that the concurrent Mo co-deposition during IB can reduce the critical incidence angle and the fluence level of terrace formation. Owing to the guidance of the IB-induced morphology, at incidence angles where a well-ordered ripple-mode can be generated, well-ordered terrace morphology is more likely to be formed. Terraced structures are initiated and further grow until the appearance of the nonlinear phase, i.e., where the ripple amplitude is sufficiently high. The enhanced terrace morphology on smooth SiO2 results from the interplay between pure IB and Mo co-deposition. The phase separation is attributed to the formation of crystalline MoOx on the side facing the impurity.

Simultaneous co-deposition of SiC and CNT into the Ni coating

Various researches are carried out to investigate the properties of Ni-SiC and Ni-CNT composite coatings. The simultaneous effect of carbon nanotube (CNT) and silicon carbide (SiC) is not addressed in the literature. Hence, Ni-SiC and Ni-SiC-CNT nanocomposite coatings were electrodeposited on aluminium substrate in this paper. Surface hardness and elastic modulus of the coatings were measured by atomic force microscope, and X-ray diffraction technique was used to evaluate the grain size of the coatings. Pin-on-disk wear test was carried out and the frictional surfaces along with the morphology of the coatings were investigated using scanning electron microscope. Both hardness and elastic modulus of the coating increased after CNT was introduced. The results indicate that CNT improved the wear behaviour of the coating by preventing the detachment of strengthening particles from the coating and consequently decreasing its abrasive wear.

Mössbauer spectroscopy study of surfactant sputtering induced Fe silicide formation on a Si surface

The formation of Fe silicides in surface ripple patterns, generated by erosion of a Si surface with keV Ar and Xe ions and simultaneous co-deposition of Fe, was investigated with conversion electron Mössbauer spectroscopy, atomic force microscopy and Rutherford backscattering spectrometry. For the dot and ripple patterns studied, we find an average Fe concentration in the irradiated layer between 6 and 25at.%. The Mössbauer spectra clearly show evidence of the formation of Fe disilicides with Fe content close to 33at.%, but very little evidence of the formation of metallic Fe particles. The results support the process of ion-induced phase separation toward an amorphous Fe disilicide phase as pattern generation mechanism. The observed amorphous phase is in agreement with thermodynamic calculations of amorphous Fe silicides.