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The influence of the reaction gas composition during the DC magnetron sputtering process on the structural, chemical and optical properties of Ce-oxide thin films was investigated. X-ray diffraction (XRD) studies confirmed that all thin films exhibited a polycrystalline character with cubic fluorite structure for cerium dioxide. X-ray photoelectron spectroscopy (XPS) analyses revealed that cerium is present in two oxidation states, namely as CeO 2 and Ce 2 O 3 , at the surface of the films prepared at oxygen/argon flow ratios between 0% and 7%, whereas the films are completely oxidized into CeO 2 as the aforementioned ratio increases beyond 14%. Various optical parameters for the thin films (including an optical band gap in the range of 2.25–3.1 eV) were derived from the UV–Vis reflectance. A significant change in the band gap was observed as oxygen/argon flow ratio was raised from 7% to 14% and this finding is consistent with the high-resolution XPS analysis of Ce 3d that reports a mixture of Ce 2 O 3 and CeO 2 in the films. Density functional theory (DFT+U) implemented in the Cambridge Serial Total Energy Package (CASTEP) was carried out to simulate the optical constants of CeO 2 clusters at ground state. The computed electronic density of states (DOSs) of the optimized unit cell of CeO 2 yields a band gap that agrees well with the experimentally measured optical band gap. The simulated and measured absorption coefficient ( α ) exhibited a similar trend and, to some extent, have similar values in the wavelength range from 100 to 2500 nm. The combined results of this study demonstrate good correlation between the theoretical and experimental findings. [ABSTRACT FROM AUTHOR]

For thermal energy storage, the most promising method that has been considered is latent heat storage associated with molten salt mixtures as phase-change material (PCM). The binary salt mixture lithium chloride—lithium hydroxide (LiCl–LiOH) with a specific composition can store thermal energy. However, to the best of our knowledge, there is no information on their thermal stability in previous literature. The key objectives of this article were to investigate the thermophysical properties, thermal repeatability, and thermal decomposition behavior of the chosen binary salt mixture. FactSage software was used to determine the composition of the binary salt mixture. Thermophysical properties were investigated with a simultaneous thermal analyzer (STA). The thermal results show that the binary salt 32 mol% LiCl-68 mol% LiOH melts within the range of 269 °C to 292 °C and its heat of fusion is 379 J/g. Thermal repeatability was tested with a thermogravimetric analyzer (TGA) for 30 heating and cooling cycles, which resulted in little change to the melting temperature and heat of fusion. Thermal decomposition analysis indicated negligible weight loss until 500 °C and showed good thermal stability. Chemical and structural instability was verified by X-ray diffraction (XRD) by analysing the binary salt system before and after thermal treatment. A minor peak corresponding to lithium oxide was observed in the sample decomposed at 700 °C which resulted from the decomposition of LiOH at high temperature. The morphology and elemental distribution examinations of the binary salt mixture were carried out via scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). X-ray photoelectron spectroscopy was conducted for surface analysis, and their elemental composition verified the chemical stability of the binary salt mixture. Overall, the results confirmed that the binary salt mixture is a potential candidate to be used as thermal energy storage material in energy storage applications of up to 500 °C. [ABSTRACT FROM AUTHOR]

Abstract: One of the toughest challenges that hinders the application of ceramic coatings is their poor damage tolerance. Addressing this problem requires the development of novel micro- or nanostructures that would impart to these coatings both high hardness and high toughness. In this paper, CrAlN coatings, with varying Al contents up to 30at.%, were engineered onto steel substrates using the magnetron sputtering technique. Whilst the addition of Al does not significantly alter the columnar microstructure, it does change the preferred grain orientation and increase the compressive residual stress. Moreover, the hardness, elastic strain to failure (H/E) and plastic deformation resistance (H 3/E 2) of the resultant CrAlN coating with the highest Al content were found to increase ∼47, ∼29 and ∼140%, respectively, as compared to CrN. Evidence collected from transmission electron microscopy and X-ray photoelectron spectroscopy experiments shows that AlN, existing in an amorphous state at the columnar CrN grain boundaries, has a crucial role in providing the unusual combination of high hardness and exceptional damage resistance. The results provide a new pathway to developing durable ceramic coatings suitable for applications involving severe loading conditions. [Copyright &y& Elsevier]

Nanostructured thin film coatings of copper oxide (Cu-oxide) were investigated to determine their physical structure, surface morphology, surface electronic bonding states, and optical properties. The Cu-oxide had been coated onto reflective aluminum substrates via a facile one-step sol–gel dip-coating route using a copper nitrate precursor. Characterizations were conducted using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), and ultra-violet visible (UV–Vis) spectroscopic methods, and representative sol-gel reactions using copper nitrate precursor were proposed. The XPS spectra confirmed the presence of copper oxide elements. Further exploration of the Cu2 p 3/2 peak in XPS spectra revealed that the electronic structure of the copper component consisted of tetrahedral Cu(I) and octahedral Cu(II) with the presence of octahedral Cu(II) enabling coatings to have high absorption levels across the solar spectrum. The deconvolution of the O1 s spectra exhibited three curve-fitting components: the lattice O2−, surface oxygen, and subsurface O− species. FESEM results showed that the coating surface was an agglomerated copper oxide nanoparticles structure forming a porous structure. The optical band-gap of Cu-oxide thin film coatings, via the Tauc plot, was 2.7 eV. [ABSTRACT FROM AUTHOR]

Abstract This article presents a comprehensive study on surface chemical bonding states, morphological features, mechanical properties, finite element modeling, and water contact angle measurements of wet chemical based dip-coated CoZn-oxide thin film coatings. Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), Nanoindentation, finite element method (FEM) modeling, and drop shape analysis techniques were used to carry out the detailed measurements. AFM studies showed that the surface roughness values of all the coatings sturdily increased with the increase in sol concentrations. The gradual increase in sol concentrations and annealing temperature also had a remarkable influence over the Co , and Zn-contents of these coatings given by XPS analysis. The deconvolution of Co 2 p 3/2 photoelectron lines revealed the formation of Co(OH) 2 , CoO, Co 2 O 3 , and Co 3 O 4 phases from the coatings surface while low intensity satellite peaks developed due to a partial spinel lattice structure of Co-ions. The occurrence of Co 3 O 4 , CoO, and ZnO phases were also confirmed from the deconvolution of O 1 s photoelectron lines. The elastic modulus, E , of CoZn-oxide thin film coating, varied within the range of 43.7–69.2 GPa was comparable with that in CoCuO thin film coatings. The maximum stress level induced was estimated to be in the range of 4.0–6.5 GPa. However, as the thickness of the coatings is increased, the maximum stress level slightly decreased. The coatings were moderately hydrophobic. [ABSTRACT FROM AUTHOR]

Abstract The temperature dependence of phase composition and lattice parameters, for TiAl x N thin film coating, are experimentally investigated by in-situ synchrotron radiation X-ray diffraction (SR-XRD), at temperatures between 25 °C and 700 °C. Mechanical properties, such as: Young's modulus (E), hardness (H) and plastic deformation index (PDI) – were experimentally determined by nanoindentation, at 25 °C. Crystalline structural analysis, of SR-XRD results, indicates the major phases are TiN and AlN; with Ti 2 O and TiO 2 phases also present above 600 °C. The lattice constants increased with an increase in temperature. Atomic and phase compositions, at 25 °C, were also verified by X-ray photoelectron spectroscopy (XPS). Field emission scanning electron microscopy (FESEM) images display an increase in surface roughness and reduction in grain size, with increasing Aluminium percentage (Al%). Nanoindentation analysis showed a maximum hardness of 25.1 ± 1.5 GPa (sample containing 12% Al), which was subsequently reduced upon addition of more Aluminium. Finite element modelling (FEM), including von Mises stress distribution, indicates lower mechanical integrity, for samples with high Al% content. Highlights • Hardness increase upon the addition of small amounts of Aluminium doping. • Significant increase in resistance of plastic deformation with increasing doping. • High temperature in-situ analysis detected an increase in lattice parameters. • Film coatings with different doping exhibited different oxidation states. • Finite element modelling evaluated mechanical integrity of films under load. [ABSTRACT FROM AUTHOR]

Molecularly imprinted polyacrylamide cryogels were synthesized with pending templates (bovine serums of different concentrations). As the serum concentrations increased in the monomer solutions, the resulting cryogels could adsorb and deplete more proteins from serum samples. Due to the addition of vinyltriethoxysilane (VTEOS) in the prepolymerizing solutions, the polymers came as organic-inorganic hybrid materials. It endued the silica-modified amphoteric polyacrylamide cryogels with improved mechanical strengths. Scanning electron micrography (SEM), Infrared (IR) spectrometry, thermogravimetry-differential thermal analysis (TG-DTA), and X-ray photoelectron spectroscopy (XPS) were carried out to characterize these macroporous polymers. Amphoteric cryogels proved to be favorable materials recognizing and binding proteins. When used as liquid chromatography stationary phases, they were capable of simultaneously adsorbing various serum proteins. Electrophoresis showed that abundant proteins were gradually depleted by the cryogels prepared from increased ratios of bovine serums in the monomer solutions. As abundant proteins are always imprinted first, this sample per se imprinting method provides an effective and convenient way to deplete abundant proteins from complex samples such as serums, meanwhile concentrating and collecting scarce species therein. [ABSTRACT FROM AUTHOR]

Titanium-doped indium tin oxide thin films were synthesized via a sol-gel spin coating process. Surface chemical bonding states and mechanical properties have been investigated as a function of titanium content (2 and 4 at%) and annealing temperature ranging from 400 to 600 °C with increments of 100 °C. Raman analysis was performed to study the phonon vibrations for the prepared samples and the results revealed the existence of ITO vibrational modes. The elemental compositions, bonding states and binding energies of the film materials were investigated using X-ray photoelectron spectroscopy (XPS) technique. The XPS results indicated that the ratio of the metallic elements (In, Sn, Ti) to the oxygen on the surface of the thin film coatings decreased due to the increase of the oxide layer on the surface of the thin films. Also, by increasing the annealing temperature up to 600 °C, the Ti 2p and Cl 2p signals were no longer detected for both 2 and 4 at% Ti contents, respectively, due to the thicker surface oxidation layer. Mechanical properties of the synthesized films were also evaluated using a nanoindentation process. Variations in the hardness ( H ) and the elastic modulus ( E ) were observed with different Ti at% and annealing temperatures. The hardness is within the range of 6.3–6.6 GPa and 6.7–6.8 GPa for 2 and 4 at% Ti content samples, respectively, while the elastic modulus is within the ranges of 137–143 and 139–143 GPa for 2 at% and 4 at% Ti contents samples, respectively. A combination of the highest H and E were achieved in the sample of 4% Ti content annealed at 600 °C. Furthermore, the H/E ratio ranges from 4.5 × 10 −2 to 5.0 × 10 −2 which reflects a reasonable level of wear resistance. [ABSTRACT FROM AUTHOR]