Electrochemical composite deposition of Sn–Ag–Cu alloys

The dominant materials used for solders in electronic assemblies over the past 60 years have been Pb–Sn alloys. Increasing pressure from environmental and health authorities has stimulated the development of various Pb-free solders. One of the most promising replacements is eutectic or near-eutectic Sn–Ag–Cu alloys produced by electrodeposition. In this study, simple and “green” Sn–Cu-citrate solutions with suspended Ag particles have been developed and optimized for electrochemical composite deposition of eutectic and near-eutectic Sn–Ag–Cu solder films. Different plating conditions, including solution concentration, current density, agitation and additives, are investigated by evaluating their effects on plating rate, deposit composition and microstructure.     

Serial sectioning in the SEM for three dimensional materials science

Here we explore the range of serial sectioning techniques that have evolved over the past decade, providing a comprehensive toolkit for capturing rich 3D microstructures, chemistries and crystallographic information, with sub-micron resolution at volumes that extend out to mm³ or even cm³. In each case we consider the challenges associated with their application, the volumes they can analyze, the damage to the surface they impart, and their suitability for different materials. In certain cases these warrant hybrid methods, motivating workflows that leverage multiple sectioning modes within the same instrument. Finally, we provide a perspective on their future development, including advances in data collection, segmentation, registration, data fusion, and correlative microscopy. Furthermore, the exploitation of 3D techniques for a better understanding of existing materials, and the design of new ones, is discussed through their use in multiscale modelling, digital twinning, material informatics and machine learning frameworks.     

Application of orange peel xanthate for the adsorption of Pb from aqueous solutions

Pristine orange peel was chemically modified by introducing sulfur groups with the carbon disulfide treatment in alkaline medium. The presence of sulfur groups on orange peel xanthate were identified by FTIR spectroscopic study. Equilibrium isotherms and kinetics were obtained and the effect of various parameters including equilibrium pH, contact time, temperature and initial ion concentration on adsorption of Pb²⁺ were studied by batch experiments. The maximum adsorption capacity of orange peel xanthate was 204.50 mg g⁻¹, which was found to increase by about 150% compared to that of pristine orange peel. The adsorption process can attain equilibrium within 20 min, and kinetics was found to be best-fit pseudo-second-order equation. Temperature has little effect on the adsorption capacity of orange peel xanthate. In addition, the adsorption mechanism was suggested to be complexation.     

A new “fluoride” synthesis route for successive ionic layer deposition of the ZnxZr(OH)yFz·nH2O nanolayers

It was for the fist time shown that hydroxo-fluoride nanolayers with the general formula M_xZr(OH)_yF_z·nH₂O can be synthesized by the successive ionic layer deposition method using soluble complexes of metal fluorides as reagents. By an example of the Zn_xZr(OH)_yF_z·nH₂O nanolayers on silicon surfaces, the effect of pH, the reagent concentration, and the number of the deposition cycles was examined. The composition and structure of these layers were determined by X-ray photoelectron and FTIR transmission spectroscopy, X-ray diffraction, scanning electron microscopy (SEM), while the growth kinetics was evaluated by ellipsometry.     

Removal of direct blue-86 from aqueous solution by new activated carbon developed from orange peel

The use of low-cost, easy obtained, high efficiency and eco-friendly adsorbents has been investigated as an ideal alternative to the current expensive methods of removing dyes from wastewater. This study investigates the potential use of activated carbon prepared from orange peel for the removal of direct blue-86 (DB-86) (Direct Fast Turquoise Blue GL) dye from simulated wastewater. The effects of different system variables, adsorbent dosage, initial dye concentration, pH and contact time were studied. The results showed that as the amount of the adsorbent increased, the percentage of dye removal increased accordingly. Optimum pH value for dye adsorption was determined as approximately 2.0. Maximum dye was sequestered within 30min after the beginning for every experiment. The adsorption of direct blue-86 followed a pseudo-second-order rate equation and fit well Langmuir, Tempkin and Dubinin-Radushkevich (D-R) equations better than Freundlich and Redlich-Peterson equations. The maximum removal of direct blue-86 was obtained at pH 2 as 92% for adsorbent dose of 6gL(-1) and 100mgL(-1) initial dye concentration at room temperature. The maximum adsorption capacity obtained from Langmuir equation was 33.78mgg(-1). Furthermore, adsorption kinetics of DB-86 was studied and the rate of adsorption was found to conform to pseudo-second-order kinetics with a good correlation (R2>0.99) with intraparticle diffusion as one of the rate determining steps. Activated carbon developed from orange peel can be attractive options for dye removal from diluted industrial effluents since test reaction made on simulated dyeing wastewater show better removal percentage of DB-86.     

Under-surface observation of thin-film alumina on NiAl(100) with scanning tunneling microscopy

Scanning tunneling microscopy (STM) was used to investigate the oxide structures underlying the surface of alumina thin-film grown on NiAl(100). At a bias voltage (on the sample) below 2.0 V, STM topography images of the alumina layer beneath the surface were obtained. A probe with depth of 2-8 Å was readily attained. The under-surface observation shows that the film consists of stacked layers of alumina whereas the layered alumina unnecessarily comprises entire θ-Al₂O₃ unit cells. The lattice orientation of the upper alumina layer differs from that of the lower one by 90° — the newly grown oxide structurally matching the horizontal oxide rather than the lower oxide. The results indicate a growth process competing with the typical mode of epitaxial growth for the growth of alumina film.     

Preparation of high quality polycrystalline silicon thin films by aluminum-induced crystallization

High quality polycrystalline silicon (poly-Si) thin films without Si islands were prepared by using aluminum-induced crystallization on glass substrates. Al and amorphous silicon films were deposited by vacuum thermal evaporation and radio frequency magnetron sputtering, respectively. The samples were annealed at 500 °C for 7 h and then Al was removed by wet etching. Scanning electron microscopy shows that there are two layers in the thin films. After the upper layer was peeled off, the lower poly-Si thin film was found to be of high crystalline quality. It presented a Raman peak at 521 cm^− 1 with full width at a half maximum of 5.23 cm^− 1, which is similar to c-Si wafer.     

Combination of Instrumented Nanoindentation and Scanning Probe Microscopy for Adequate Mechanical Surface Testing

The elastic indentation modulus and hardness of standard bulk materials and advanced thin films were deter-mined by using the nanoindentation technique followed by the Oliver- Pharr post-treatment. After measure-ments with different loading/unloading schemes on chemically polished bulk titanium a substantial decrease of both modulus and hardness vs an increasing loading time was found, Then, hard nanostructured TiBN and TiCrBN thin films deposited by magnetron sputtering (using multiphase targets) on substrates of high roughness (sintered hard metal) and low roughness (silicon) were studied. Experimental modulus and hardness characterized by using two different nanoindenter tools were within the limits of standard deviation. However, a strong effect of roughness on the spread of the experimental values was observed and it was found that hard-ness and elastic indentation modulus obeyed a Gaussian distribution. The experimental data were discussed together with scanning probe microscopy (SPM) images of typical imprints taken after the nanoindentation tests and the local topography's strong correlation with the results of nanoindentation was described.     

Oxidant-assisted preparation of CaMoO4 thin film using an irreversible galvanic cell method

CaMoO₄ thin films were prepared by an irreversible galvanic cell method at room temperature; the crystalline phase structure, surface morphology, chemical composition and room temperature photoluminescence property were characterized by X-ray diffraction, Raman spectroscopy, scanning electronic microscopy, X-ray photoelectron spectroscopy as well as photoluminescence spectroscopy. Our results reveal that it is very difficult to directly deposit dense and uniform CaMoO₄ thin films in saturated Ca(OH)₂ solution at room temperature by the irreversible galvanic cell method. After adding some oxidant (NaClO solution or H₂O₂ solution), the growth of CaMoO₄ grains has been promoted, and well-crystallized, dense, and uniform CaMoO₄ films were obtained. The as-prepared CaMoO₄ films exhibit a good green photoluminescence, with the excitation of various wavelengths (220 nm, 230 nm, 240 nm, 250 nm and 270 nm) of ultraviolet irradiation.     

Measurement of the viscosity of resins used in SEM specimen preparation

Viscosities of seven different epoxy-type resins currently used in different laboratories to impregnate cement paste and concrete specimens for backscatter-mode Scanning electron microscopy were measured. The measured viscosities were found to range over more than two orders of magnitude. The most viscous of the resins tested (Araldite AY-103) apparently has difficulty in achieving the necessary penetration into dense concrete specimens. Many of the resins thicken spontaneously and gel relatively quickly after mixing, which limits their penetration, but satisfactory results can be obtained with care. Two of the resins (LR White and Spurr’s) are of much lower viscosity than the others and do not thicken spontaneously. This permits use of extended penetration times and deep penetration into even very dense concrete specimens.     

Substrate temperature dependence of electrical and structural properties of Ru films

Microstructures and resistivities of sputtered Ru films were investigated as a function of substrate temperature to obtain a single-layered Ru barrier without a Ta/TaN under layer. High resistivity Ru films with a high density of crevices, which enhances Cu diffusion along the crevices, were formed by the conventional sputtering process, i.e., sputtering at room temperature and annealing at 400 °C-700 °C for 30 min in Ar + 3%H₂. But, crevice-free and smooth Ru films with low resistivity, the same as that for the bulk phase, were formed when substrate temperature add sputtering was raised to 700 °C. Ru films formed by this process had (002) preferred orientation and then Cu (111) was formed by plating. This result corresponded to the tendency predicted by ab initio calculations.     

The effect of temperature on the growth of carbon nanotubes on copper foil using a nickel thin film as catalyst

Growth of carbon nanotubes (CNTs) on bulk copper foil substrates has been achieved by sputtering a nickel thin film on Cu substrates followed by thermal chemical vapor deposition. The characteristics of the nanotubes are strongly dependent on the Ni film thickness and reaction temperature. Specifically, a correlation between the thin film nickel catalyst thickness and the CNT diameter was found. Two hydrocarbon sources investigated were methane and acetylene to determine the best conditions for growth of CNTs on copper. These results demonstrate the effectiveness of this simple method of directly integrating CNTs with highly conductive substrates for use in applications where a conductive CNT network is desirable.     

Characterization of stacked sol-gel films: Comparison of results derived from scanning electron microscopy, UV-vis spectroscopy and ellipsometric porosimetry

TiO₂/MgF₂ bi-layers were prepared by sol-gel processing in both stacking sequences. Films were characterized by scanning electron microscopy, UV-vis spectrometry, and ellipsometric porosimetry. The results obtained by the different methods are compared. The validity and limitations of the respective techniques are discussed with special focus on film porosity and the interface between the TiO₂ and MgF₂ material.     

Growth and characterization of electrodeposited Cu(In,Al)Se2 thin films

Thin films of CuIn_1 − xAl_xSe₂ were grown using a cathodic electrodeposition technique. The CuIn_1 − xAl_xSe₂ films were electrodeposited on SnO₂ coated glass from aqueous baths containing different Al contents using deposition potentials ranging from − 650 mV to − 850 mV versus a saturated calomel electrode. The electrodeposited films were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis of X-rays, atomic force microscopy, and UV-VIS-NIR spectroscopy. The results show that single phase CuIn_1 − xAl_xSe₂ films with Al content x around 0.27-0.33 having good stoichiometry can be produced in the above potential range. XRD and SEM studies show that films deposited at − 650 mV and − 750 mV have good crystallinity while those grown at − 850 mV have comparatively poorer crystallinity. SEM studies show that the particle size of the films grown at − 650 and − 750 mV is in the micron range but is around 100 nm when grown at − 850 mV. Optical studies show that the optical band gap shifts with Al content from 1.21 eV for x = 0.27 to about 1.42 eV for x = 0.33. The as-grown as well as vacuum annealed films were n-type in conductivity with resistivity in the range 3-5 × 10⁻³ Ω cm.     

Role of zirconia filler on friction and dry sliding wear behaviour of bismaleimide nanocomposites

This paper discusses the friction and dry sliding wear behaviour of nano-zirconia (nano-ZrO₂) filled bismleimide (BMI) composites. Nano-ZrO₂ filled BMI composites, containing 0.5, 1, 5 and 10 wt.% were prepared using high shear mixer. The influence of these particles on the microhardness, friction and dry sliding wear behaviour were measured with microhardness tester and pin-on-disc wear apparatus. The experimental results indicated that the frictional coefficient and specific wear rate of BMI can be reduced at rather low concentration of nano-ZrO₂. The lowest specific wear rate of 4 × 10⁻⁶ mm³/Nm was observed for 5 wt.% nano-ZrO₂ filled composite which is decreased by 78% as compared to the neat BMI. The incorporation of nano-ZrO₂ particles leads to an increased hardness of BMI and wear performance of the composites shows good correlation with the hardness up to 5 wt.% of filler loading. The results have been supplemented with scanning electron micrographs to help understand the possible wear mechanisms.     

Effects of calcination temperature on the morphology, structure and photocatalytic activity of titanate nanotube thin films

"Titanate nanotube thin films were synthesized on titanium substrate via a simple hydrothermal method. The as-prepared film was composed of Na₂Ti₃O₇, and then transformed into H₂Ti₄O₉·H₂O after acid washing process. However, H₂Ti₄O₉·H₂O was thermally unstable. The effect of calcination temperature on its morphology (nanotube, nanosheet, nanorod or a lotus-root-like appearance), structure and photocatalytic activity was carried out by annealing the films at 300-900 °C in the static air and then analyzing by X-ray diffraction, scanning electron microscope and transmission electron microscope. Based on the results, the possible evolution mechanisms were discussed for no-acid (washed with distilled water) and acid washed (washed with dilute HNO₃) samples, respectively. Finally, the photocatalytic activity of acid washed films calcined at different temperatures was evaluated by photodegradation of methyl orange (MO) under ultraviolet light. The results indicated that the film obtained at 500 °C showed the highest rate for decomposing MO solution, which could be explained by its unique surface morphology and crystal structure.     

Nanocrystalline yttria films by plasma-assisted liquid injection (PA-LI) CVD technique using metallorganic precursors

Nanocrystalline cubic Y₂O₃ film deposition by PA-LICVD was studied at 773 K in a N₂/O₂ plasma environment with methanol and triglyme solution of aquatris(2,2,6,6-tetramethyl-3,5-heptanedionato)yttrium(III) and its polyether adduct complexes as precursors. The X-ray powder patterns are analyzed and found to be triclinic and monoclinic for Y(tmhd)₃·H₂O(1) and Y₂(tmhd)₆·triglyme (2). Y₂O₃ film with (111) plane as the dominant orientation was obtained on graphite under a deposition pressure of 0.8–1.2 mbar.