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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]

Silicon nanowires (SiNWs) have been grown on crystalline silicon (Si), indium tin oxide (ITO) and stainless steel (SS) substrates using a gold catalyst coating with a thickness of 200 nm via pulsed plasma-enhanced chemical vapor deposition (PPECVD). Their morphological, mineralogical and surface characteristics have been investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman analysis. SiNWs growth is accompanied by oxidation, thus yielding partially (SiO) and fully oxidized (SiO) Si sheaths. The mean diameters of these SiNWs range from 140 to 185 nm. Si with (111) and (220) planes exists in SiNWs grown on all three substrates while Si with a (311) plane is detected only for Si and ITO substrates. Computational simulation using density functional theory (DFT) has also been conducted to supplement the experimental Raman analyses for crystalline Si and SiO. XPS results reveal that ca. 30 % of the SiNWs have been oxidized for all substrates. The results presented in this paper can be used to aid selection of appropriate substrates for SiNW growth, depending on specific applications. [ABSTRACT FROM AUTHOR]

Abstract: New cobalt-based metal oxide thin films (MxCoyOz with M=Mn, Cu, Ni) have been deposited on commercial aluminum and glass substrates using sol–gel dip-coating method. The as-deposited films were characterized by a wide range of complementary techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), spectrophotometry and nanoindentation techniques. A light absorption study for coatings on glass substrates within a wavelength range of 300–1100nm was also conducted. Topographical and morphological investigations showed the presence of nano-sized, grain-like particles in the copper–cobalt oxide coatings, which consequently had the roughest surface among the three coatings. All coatings on glass substrate exhibited higher absorption of ultraviolet (UV) light compared to visible light, while coatings on aluminum substrate generally had low reflectance (<50%) of UV light, moderate reflectance (<80%) of visible light and high reflectance (up to 100%) of infrared light. Implications of optical properties as a function of film thickness controlled by dip-heating cycles were discussed. The elastic modulus (E) and hardness (H) of thin film samples compared with stand‐alone commercial aluminum substrate were also measured. [Copyright &y& Elsevier]

• Effect of Mo target power on vacuum sputtered Mo doped Cr nitride coatings. • The crystallite size of coatings increases with Mo target power and Mo content. • Coatings are transparent in the visible region with direct optical band gap. • Computational modelling provides insight to the electronic and optical properties. • Good solar selectivity of chromium nitride with high mechanical properties. In this study, Cr−Mo−N thin films with different Mo contents were synthesised via closed field unbalanced magnetron sputtering ion plating. The effects of Mo content on the microstructure, chemical bonding state, and optical properties of the prepared films were investigated by X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy, and ultraviolet-visible spectrophotometry. XRD results determined the face centered cubic (fcc) structure of pure CrN film. The incorporation of molybdenum (Mo) in the CrN matrix was confirmed by both XRD and XPS analyses. The CrMoN coatings demonstrate various polycrystalline phases including CrN, γ -Mo 2 N, Cr with oxides layers of MoO 3 , CrO 3 , and Cr 2 O 3. Microstructural results of the Cr-Mo-N coatings show that the grain size increased with an increase in Mo content due to the formation of MoN phase, in which the Mo atoms interact with N atoms around the grain boundaries of the CrN phase. XPS investigations confirmed the presence of Cr, Mo, N, C and O elements in the studied coatings. The optical results revealed that the synthesised coatings exhibit low reflection magnitudes in the visible region of the solar spectrum indicating good antireflection surfaces. Mo doped thin coatings improve the solar absorptance by ~76% in the wavelength range of 200–800 nm with a low thermal emittance of ~ 20% in the infrared range (up to 4000 nm). Furthermore, by applying density functional theory, the computational simulation provides similar trends as the experimental finding of absorption coefficient in the wavelength range. [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: CrN is one of the most important transition metal nitrides, used as protective and anti-wear coating in modern engineering applications. However, CrN coatings are typically brittle and susceptible to catastrophic failure. In this paper, CrNiN coatings with differing Ni contents were deposited on tool steel substrates using a closed field unbalanced magnetron sputtering system. The effects of Ni addition on the microstructure and mechanical characteristics of CrN thin films were studied by combining nanoindentation tests with cross-sectional transmission electron microscopy. A columnar structure was observed in the CrN coating. With an increase in Ni content, the resultant columnar grains exhibited a high aspect ratio. Ni additions to CrN were found to enhance its damage resistance. Notably, the CrN thin film deformed mainly by intercolumnar shear sliding, whereas plastic deformation was favored in the CrNiN thin films exhibiting high aspect ratio columnar grains. More significantly, this change of microstructure with enhanced Ni content led to improved damage tolerance, manifested by a higher load required for crack formation upon a sharp contact (expressed as 1/HE 2), and the plastic energy absorbed during nanoindentation. [Copyright &y& Elsevier]

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]

Possessing the ability to tune the work function and band gap of transparent conducting oxides (TCOs) is widely sought after, as it allows for improved band alignment in electronic and optoelectronic applications, enhancing overall device performance. Out of the many TCOs, Al-doped zinc oxide (AZO) has received considerable interest for electrode application due to its low electrical resistivity, high optical transparency in the visible regime, and room-temperature fabrication capability. In this study, we report on the effects of post fabrication air-annealing on the work function and band alignment of AZO deposited at room temperature by DC-magnetron sputtering. AZO films were air-annealed at temperatures varying from 25 °C (as-deposited) to 600 °C. The Fermi energy levels, work function values, surface chemistry, and optical band gaps of the AZO films were investigated via X-ray photoelectron spectroscopy (XPS) and UV–Vis spectroscopy. An increase of the work function from ~5.53 eV to ~6.05 eV is observed to take place over an increase of annealing temperatures from 25 °C (as-deposited) to 600 °C, determined to be the result of a decrease in carrier concentration through the promoted extinction of oxygen vacancies. Via XPS analysis, the increased extinction of oxygen vacancies was confirmed due to a notable shift from an oxygen-deficient state to an oxygen-sufficient state in the high resolution O 1s peaks, for which the activation energy was found to be 33.3 meV. Over the course of increasing annealing temperatures, the optical band gap saw a shift from ~3.55 eV to ~3.37 eV, following the Burstein-Moss phenomenon due to a decrease in carrier concentration, further verifying an increase in oxygen vacancy extinction. The reported results confirm that work function tuning of AZO films can be achieved through simple post-fabrication air-annealing. • Facile tuning of the work function of Al-doped ZnO films for band alignment • Identification of the native defect-based doping mechanism through XPS analysis • Identification of donor level location within the bandgap [ABSTRACT FROM AUTHOR]

• First growth kinetic studies for oxidative chemical-vapor-deposited (oCVD) PEDOT. • Significantly large carrier mean free path (>5 nm) for oCVD PEDOT. • Conjugation and doping level-dependent carrier transport behaviors. This study is aimed to enhance the understanding of the processing-structure-property relationship in oxidative chemical vapor deposition (oCVD) conjugated polymers. Particular focus is made on the substrate and oxidant temperatures for the oCVD poly(3 4-ethylenedioxythiophene) (PEDOT) growth and their effects on the structure and electrical properties on resulting thin films. Doping levels are evaluated using Fourier-transform infrared spectroscopy and x-ray photoelectron spectroscopy, which is complemented by Hall Effect investigations. Further, the relationship between doping level and conjugation length is described with discussion on mean free path, where the mean free path of oCVD PEDOT (up to ~5 nm) is significantly larger than typical organic semiconductors and comparable to conventional inorganic counterparts. The mechanisms that govern oCVD film growth are suggested, which is strongly dependent on both substrate and oxidant sublimation temperatures. Finally, the carrier transport behaviors, dominated by conjugation and doping levels are discussed. [ABSTRACT FROM AUTHOR]

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]

This contribution investigates the impact of adding transition metal of Ti to CeO y samples at various concentrations referring to 0, 15.84, 24.46, 34.46, 36.23, 38.46, 45.38% and pure TiO y , correspondingly. The samples were fabricated by the magnetron sputtering technique. X-ray diffraction (XRD) configurations demonstrate the presence of α-Ce 2 O 3 and Ce 2 O 3 phases with increased Ti contents in the systems. X-ray photoelectron spectroscopy (XPS) experimentation confirms the purity of the S1-sample (CeO 2) and the purity of the S8-sample (TiO 2). Further XPS analysis reveals that Ti incorporation in the doped systems functions as a reducing agent because of the existence of α-Ce 2 O 3 and Ce 2 O 3 phases. Moreover, based on UV–vis spectroscopy results, the studied samples exhibit indirect optical energy band-gaps reduced from 2.6 to 2.35 eV with the increase of Ti concentrations of 0–45.38% in (S1-S7), respectively. In reference to bandgap 2.35 eV, a slight rise in band gaps was detected for S3 sample. However, an observable increase in the band gap of 2.9 eV occurred for S8 (pure TiO 2). Optical analysis of the calculated energy loss parameters demonstrates that all the studied samples reveal small amounts of energy loss. Our results suggest that the improved optical properties of Ti-doped CeO y films could serve for various optical applications. [ABSTRACT FROM AUTHOR]

Herein, the closed field unbalanced magnetron sputtered CrNiN, CrNiSiN, and CrNiAlN coatings are studied to gain insights into their structural, morphological, optical, and mechanical properties. Detailed characterizations of the thin films have been carried out through X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible–near infrared (UV–Vis) spectroscopy, nanoindentation, finite element modeling (FEM), and water contact angle measurements. XRD confirmed the hexagonal close-packed hcp-Cr 2 N (211) phase and face-centered cubic fcc-CrN (200) phase. The SEM images confirmed the compact, dense, and uniform distribution of gains in the coating structures. The average crystallite size of CrNiN coatings was 515 nm. The addition of substituents (Si and Al) to the CrNiN coatings resulted in increasing the crystallite sizes to 605 nm (for CrNiSiN) and 811 nm (for CrNiAlN) as well as grain size from 1.32 to 2.335 μm. XPS analysis was conducted to estimate the atomic constituents and measure the high-resolution XPS spectra of Ni2 p photoelectron lines. The elastic modulus and hardness of the coatings are between 361 and 459 GPa, and 23.1–26.8 GPa, respectively. The Si, and Al additions enhanced both Young's modulus and the hardness of the coatings. Results of FEM modeling demonstrated the stress distribution within the coatings on steel and silicon substrates at different film thicknesses. The maximum stress level was increased by 30% at the coatings' upper portion, while that of the interface was reduced by 60%. The water contact angle values lay within the range of 102.4°–112.4°. [Display omitted] • Hexagonal close packed CrN phase was detected and existence of Cr, Ni, Al, Si, and N were confirmed via XPS analysis. • An average grain size of 515 nm was recorded for CrNiN thin films. • The doublet separation energy of 10.8 eV between the Cr2 p 3/2 and Cr2 p 1/2 levels was detected. • A very high Young's modulus of 458.7 GPa was attained by CrNiN thin films. • Water contact angle of CrNiN thin films lies within the range of 102.4–112.4°. [ABSTRACT FROM AUTHOR]