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• The elastic recoil detection analysis shows 41 at.% of H absorbed in CP-Ti. • The amount of hydrogen absorbed by Ti-6Al-4V alloy was 31 at.%. • Pd layer improved the hydrogen absorption capacity of Ti-6Al-4V alloy to 36 at.%. • The H depth profile shows the highest diffusion depth in CP-Ti. Hydrogen storage capacity of CP-Ti, Ti-6Al-4V alloy, and Ti-6Al-4V alloy coated with a thin Pd layer was investigated. All samples were hydrogenated at 550 °C for 3 h in 15% hydrogen and 85% argon gas mixture. The hydrogen content and its depth profile were investigated using elastic recoil detection analysis (ERDA) while the X-ray diffraction was used for phase analysis. The highest average content of hydrogen of (41 ± 60) at.% was absorbed in CP-Ti while (31 ± 4) at.% H was determined in Ti-6Al-4V alloy. The presence of a thin Pd catalytic layer improved the hydrogen absorption of alloy to (36 ± 3) at.% H. With the beam energy of 3 MeV, H was profiled up to (4520 ± 410) × 1015 atoms/cm2, (3250 ± 300) × 1015 atoms/cm2 and (3950 ± 360) × 1015 atoms/cm2 in CP-Ti, Ti-6Al-4V alloy and in the coated system respectively. The TiH 2 hydrides were found in all three systems in addition to Pd 3 Ti phase in the Pd/Ti-6Al-4V coated system. [ABSTRACT FROM AUTHOR]

Abstract Silicon (Si) has been the most widely used semiconductor for decades, playing an important role in the field of electronics, energy conversion and energy storage. Because of their unique morphological energy band characteristics, Si nanostructures exhibit superior performance in many applications in comparison with their bulk counterparts. In this study, the effects of thermal annealing on elemental composition and morphological properties of palladium metal thin films grown on c-Si substrates were investigated. Palladium (Pd) thin films of different thicknesses were deposited on Si (1 0 0) with and without native oxide layers by electron beam evaporation and annealed in vacuum at 600 °C for two hours. Scanning electron microscopy (SEM) studies have shown that the surface morphology showed an effective dewetting in individual droplets and islands which further coalesce into bigger islands. Rutherford backscattering spectrometry (RBS) and electrical measurements analyses revealed the diffusion of the Si substrate into the Pd layer during annealing. This contribution will discuss the effects of the metal layer thickness as well as the native oxide on the metal thin films. [ABSTRACT FROM AUTHOR]

Hydrogen effusion from hydrogenated amorphous silicon (a-Si:H) and amorphous silicon carbide (a-Si 1− x C x :H) thin films during a temperature ramp between RT and 600 °C was studied by in situ real-time elastic recoil detection analysis. Point to point contour maps show the hydrogen depth profile and its evolution with the ramped temperature. This paper proposes a diffusion limited evolution model to study H kinetic properties from total retained H contents recorded in a single ramp. In a compact a-Si:H layer where H predominantly effuses at high temperatures between 500 and 600 °C, an activation energy value of ∼1.50 eV and a diffusion pre-factor of 0.41 × 10 −4 cm 2 /s were obtained. Applied to an non-stoichiometric a-Si 1− x C x :H film in the same range of temperature, the model led to reduced values of activation energy and diffusion prefactor of ∼0.33 eV and 0.59 × 10 −11 cm 2 /s, respectively. [ABSTRACT FROM AUTHOR]

Nanostructured thin silicon-based films have been deposited using the hot-wire chemical vapour deposition (HWCVD) technique at the University of the Western Cape. A variety of techniques including optical and infrared spectroscopy, Raman scattering spectroscopy, X-rays diffraction (XRD) and transmission electron microscopy (TEM) have been used for characterisation of the films. The electrical measurements show that the films have good values of photoresponse, and the photocurrent remains stable after several hours of light soaking. This contribution will discuss the characteristics of the hydrogenated nanocrystalline silicon thin films deposited using increased process chamber pressure at a fixed hydrogen dilution ratio in monosilane gas. [ABSTRACT FROM AUTHOR]

Abstract: Results of photoresponse, activation energy and light soaking measurements on selected hydrogenated nanocrystalline Si thin films are presented. The films were deposited by hot-wire chemical vapour deposition. Values of photoresponse better than 1×102 were obtained. They are lower for porous material as the crystalline volume fraction increases. Activation energy results are related to the intrinsic character and the microstructure of the films. Light soaking experiments show that the nanocrystalline films are very stable. Their amorphous counterparts attain a stable photoconductivity value after 300 h of illumination. [Copyright &y& Elsevier]

Ion beam induced modification of thin metallic films is an emerging approach to grow metallic nanoparticles controllably. Modification of thin solid films is helpful in fabricating arrays of nanoscale particles for electronic and photonic devices and for the catalyzed synthesis of nanotubes and nanowires. In this work, the modification and nanostructures formation over the surface of SiC/Pd thin films of 15 and 45 nm thicknesses, grown on crystalline Silicon (c-Si) substrate by electron beam deposition, upon ion irradiation, have been investigated by means of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Rutherford backscattering spectrometry (RBS), Fourier Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy. The SiC/Pd bilayer films were irradiated with 100 keV Ar+ ions at fluences of 1 × 1015 and 5 × 1015 ions/cm2 at room temperature. The surface morphology from SEM analysis showed the formation of nanoparticles that were interconnected after irradiation. The RBS and EDS results confirmed the presence of Pd, C, O and Si. While the Raman spectrum of the pristine sample displayed only a sharp peak at 520 cm−1 characteristic to c-Si substrate, the spectra of the irradiated sample red-shifted to lower wavenumbers indicating the appearance of Si nanocrystals.. Hence, ion beam irradiation is a promising method for the fabrication of SiC nanostructures on c-Si substrate. [ABSTRACT FROM AUTHOR]

Abstract: It proves difficult to obtain a set of protocrystalline silicon materials with different characteristics from the same deposition chamber to study the exact nature of these transition region materials. Hot-wire deposited protocrystalline silicon was thus isochronically annealed at different temperatures to investigate the bonded hydrogen configurations and structural disorder. Modeling of optical reflection and transmission spectra with Scout® yielded the optical parameters and infrared spectroscopy confirms that bonded hydrogen remains in the material, with the exception of a longer anneal of six hours at 520°C. Sub bandgap absorption as inferred from photothermal deflection spectroscopy was related to these characteristics. [Copyright &y& Elsevier]

The effect of naturally occurring oxide and oxidised layers formed by ion implantation and thermal oxidation on hydrogen absorption was investigated in Ti-6Al-4V alloy samples as a possible candidate for hydrogen storage. The samples were implanted with two different oxygen fluences (1.5 × 10 17 and 3.0 × 10 17 ions/cm 2 ) at room temperature and 550 °C, and comparison was made with thermally oxidised samples at a temperature of 550 °C for 2 h. All samples were afterwards hydrogenated at 550 °C for 2 h. The elastic recoil detection analysis show that approx.14 at.% H was absorbed in as-received and thermally oxidised samples. The native oxide layer and the oxidised layer formed by thermal oxidation enhanced the absorption of hydrogen regardless of their different thickness and stoichiometry. The amount of hydrogen, however, was significantly lower in implanted samples, approx. 3–5 at.%, suggesting that oxygen ions implanted in alloy prevent hydrogen absorption. It was found that the average amount of absorbed hydrogen within the projected depth was reduced due to implantation of oxygen ions regardless of their fluences and implantation temperature. The hydrides were not determined in any of investigated samples while the surface hardness of all samples increases after hydrogenation although to different extent. [ABSTRACT FROM AUTHOR]

We report on the poisoning of tungsten filaments during the hot-filament chemical vapour deposition process at typical carbon nanotube (CNT) deposition conditions and filament temperatures ranging from 1400 to 2000 °C. The morphological and structural changes of the filaments were investigated using scanning electron microscopy and X-ray diffraction, respectively. Our results conclusively show that the W-filament is not stable during the carburization process and that both mono- and ditungsten-carbides form within the first 5 min. Cracks and graphitic microspheres form on the carbide layer during the first 15 min at the temperatures ≥1600 °C. The microspheres subsequently coalesce to form a graphite layer, encapsulating a fully carburized filament at the temperature of 2000 °C after 60 min, which inhibits the catalytic activity of the filament to produce atomic hydrogen. The structural changes of the filament also induce variations in its temperature, illustrating the instability of the filament during the deposition of CNTs. [ABSTRACT FROM AUTHOR]

• Surface treatment of the stainless steel (SS) within the shortest duration of 2 h using hydrothermal method was successful. • The treated surface exhibits an excellent absorptance of 0.931 in the UV–vis-NIR wavelength region. • Thus, treated surface of the SS has the potential for its use in the photon-thermal conversion application. This work aims to improve the absorption properties of stainless-steel (SS) (434-L) using a hydrothermal treatment method. Therefore, four SS films were prepared at different treatment times, i.e., 1 h, 2 h, 3 h and 24 h. The XRD results revealed the transformation of the crystal structure of the as-received SS from Body-centered cubic (BCC) to Face-centered cubic (FCC) of FeFe 2 O 4 after treatment at 200 °C. The SEM results showed micro-pores distributed across the surface of the films, whereas the AFM results revealed an increment in surface roughness of the films as the duration of the treatment extended. The absorptance (α) of the SS was enhanced from 0.350 to 0.931 after the treatment. This improvement was attributed to surface oxidation and micro-pores distributed across the surface of the films, as confirmed by EDS and SEM results. On the other hand, the high emissivity (0.41) recorded was attributed to the large surface roughness (137.8 nm) of the film. Based on the UV–vis results, the optical reflectance of the film in the short wavelength of the solar spectrum was reduced from ~80 to ~8% resulting in a significant improvement in the absorptance of the SS. [ABSTRACT FROM AUTHOR]