Search

[Display omitted] • The surface chemical composition of β-Ga 2 O 3 films is discussed in depth. • The component of O 1s with the binding energy around 531.8 eV is attributed to surface lattice O atoms. • The defects inside the β-Ga 2 O 3 films were analyzed by HRTEM. β gallium oxide (β-Ga 2 O 3) is an ultrawide bandgap semiconductor with great potential for solar-blind ultraviolet detection, power devices, and gas sensing. However, the understanding of the surface properties of β-Ga 2 O 3 remains insufficient. Here, epitaxial growth of β-Ga 2 O 3 films was carried by metal–organic chemical vapor deposition (MOCVD) on sapphire substrates. The surface chemical composition, surface layer crystalline properties, and surface morphology of the β-Ga 2 O 3 films were discussed and analyzed in detail. By comparing the atomic ratios of O/Ga, the surface morphology, and the crystalline properties of the films, we attribute the component of O 1s with the binding energy around 531.8 eV to surface lattice O atoms. Moreover, the one-dimensional defects inside the surface layers and the near-interface regions of the films were observed at atomic scale by high resolution transmission electron microscopy (HRTEM). By comparing the lattice fringes of different facets, the geometric phase uniformity, and the distribution of strain, we found that the crystalline quality of the surface layers is much higher than the near-interface regions. [ABSTRACT FROM AUTHOR]

One dimensional Gd 2 O 3 nanorods with 5% Eu substitution at Gd-site have been synthesized by a simple, inexpensive, hydrothermal process without using any catalyst or template. Structural, spectroscopic, magnetic and magnetocaloric properties of these nanorods are studied. Powder X-ray diffraction data confirm that these samples have cubic structure (Space group Ia-3) at 300 K. High resolution transmission electron microscopy images suggest the average diameter of nanorods to be ~14 nm. However, the rod length is found to vary from about 50 nm to 140 nm. Raman spectrum shows a peak at ~363 cm−1 as expected for the cubic phase of Gd 2 O 3. The 5% Eu substituted Gd 2 O 3 sample remains paramagnetic from 300 K down to 5 K. Using magnetization–field data obtained at various temperatures, isothermal magnetic entropy change (ΔS m) is calculated. The maximum ΔS m value at 6 K for 70 kOe field change is about −30.3 Jkg−1 K−1. This value is quite large compared to that of the pure Gd 2 O 3 nanotube samples. Thus nanostructured Gd 2 O 3 with small rare-earth substitution at Gd-site exhibit appreciable magnetocaloric effect and these nanomaterials may be suitable for low temperature magnetic refrigeration applications. • Eu-doped Gadolinium oxide (Gd 2 O 3) nanorods have been synthesized using a simple surfactant/template/catalyst-free hydrothermal method. • Magnetic and optical properties of 5% Eu-substituted Gd 2 O 3 nanorods are studied. • Surface spin disorder leads to enhanced magnetization and magnetocaloric effect at low temperatures. [ABSTRACT FROM AUTHOR]

The 0.9 MgTiO 3 –0.1Ba 5 Nb 4 O 15 (0.9MTO-0.1BNO) thin films deposited on Pt (111)/TiO 2 /SiO 2 /Si (100) and SiO 2 substrates by RF reactive magnetron sputtering have been reported. The films are deposited at a substrate temperature of 400 °C under 50/50 argon (Ar 2)/oxygen (O 2) mixed ambiance by varying the film thickness. The X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) studies have confirmed presence of both MTO and BNO phases.. The obtained strain in the films is found to be reduced with an increase in film thickness. The 3d crystal structure of MTO exhibited significant variations in bond length for the films with different thicknesses. The dispersion in the refractive index of the films has obtained using the single electronic oscillator model, and the obtained bandgap value is found to be reduced from 3.75 to 3.34 eV with an increase in film thickness from 150 to 340 nm, accordingly. The films revealed uniform spherical shaped particles with smooth surface with small rms roughness values around 2.9 to 2 nm. The microwave and low frequency dielectric responses showed improvment with an increase in film thickness. The impedance spectroscopy analysis displayed Cole-Cole behavior indicating the non-Debye conduction process present in the films. The frequency dependent conduction process has analyzed by Jonscher's Power law and the non-overlapping small polaron hopping nature has been observed. Extracted activation energies estimated from conductivity are found to be in the range of 0.31 eV to 0.14 eV. The leakage current density (J) with the applied potential has found to be in the range of 10−6 A/cm2 at 100 kV/cm2 for 340 nm film. The obtained results suggest that these films are promising for optical and microwave integrated circuit applications. Unlabelled Image • MTO-BNO films were fabricated for microwave integrated circuit applications. • The fraction of O 2 in deposition chamber played crucial role in the growth of films. • Post annealing treatment is necessary for crystallization of the fabricated films. • Good quality films with minimal roughness are obtained by RF magnetron sputtering. • Obtained electrical responses are reasonably good for the intended application. [ABSTRACT FROM AUTHOR]

The composites composed of Mg 22 (LaY) 2 Ni 10 as-quenched alloy and x wt% MoS 2 (x = 0–10) catalyst were prepared by high-energy ball milling. The phase composition, microstructure and hydrogen storage dynamics were characterized by X-ray powder diffraction, scanning electron microscopy, high resolution transmission electron microscopy, differential scanning calorimetry and Sievert's measure method, respectively. Experimental results show that there are Mg 2 Ni, LaMg 3 , La 2 Mg 17 and Mg 24 Y 5 phases in the composites, the addition of MoS 2 leads to the formation of MgS and its intensity strengthens with the increase of MoS 2. The sequence in which the average grain size decreases from large to small is 0 wt% MoS 2 , 10 wt% MoS 2 , 1 wt% MoS 2 , 5 wt% MoS 2 and 3 wt% MoS 2. For granularity, the suitable amount of MoS 2 is 3 wt%, which gives a useful influence on decreasing particle size and enhancing grinding efficiency in this experiment. For the 3 wt% and 10 wt% MoS 2 composites, there are a large number of amorphous embedded by a small amount of nano scale grains. The misorientation angle between two adjacent Mg 2 Ni grains belongs to the large angle grain boundary. Compared with the other composites, the amorphous phase of the 3 wt% MoS 2 composite is relatively large, and the phase boundaries of atoms are relatively disordered. These composites have good activation characteristics. The hydrogen absorption capacity can reach their respective maximum after 2–4 cycles. The hydrogen absorption rate is greater whether the composites contain MoS 2 at higher temperature (350 °C), and can attain saturation point within 18 min. By contrast, the 1 wt% and 3 wt% MoS 2 composites can saturate within 5.4 and 8.5 min, respectively. Their maximum saturated hydrogen absorption capacity reduces from 3.811 wt% to 2.748 wt% when MoS 2 catalyst rises from 0 to 10 wt%. The time required for 90% of the saturated hydrogen absorption capacity (T 90% C max) both first shorten and then extend with the increase of MoS 2. Although the saturated hydrogen absorption capacity of 3 wt% MoS 2 composite is lower than 0 wt% and 1 wt% composites, its T 90% C max are superior to them. At higher temperature (350 °C), the hydrogen absorption saturation ratio (R 1min) rises from 57.49% to 86.29% with MoS 2 amount increases from 0 to 5 wt%, and then lessens to 67.54% when the MoS 2 amount further increase up to 10 wt%. The amount of saturated hydrogen desorption capacity (C ′ max) of the composite decreases with the increase of MoS 2. Compared with 0 wt% MoS 2 and 10 wt% MoS 2 composites, the activation energy of hydrogenation and dehydrogenation for the 3 wt% MoS 2 composite is relatively low. Comprehensive comparison find that the 3 wt% MoS 2 composite has the best hydrogen desorption kinetics, a small or excessive amount of MoS 2 both decreases dehydrogenating rate. Comprehensive analysis shows that the 3 wt% MoS 2 composite contains amorphous and nanocrystalline crystals, displaying a good hydrogen absorption/desorption kinetics, even at 100 °C. Excessive or too little MoS 2 can improve the hydrogen absorption and desorption performance of the as-milled composites in our experiment. • Amorphous and nanocrystalline MgLaYNi-MoS 2 composites are prepared by ball-milling. • Composites with different MoS 2 content show a distinct difference in microstructure. • Adding a proper amount MoS 2 remarkably improves H 2 ab/desorption performance. • Overdoping MoS 2 result in a poor catalytic effect. [ABSTRACT FROM AUTHOR]

In this study, we demonstrated the formation of a new type of AuAg@Ag nanostructure in titanium nitride (TiN) thin films using sequential implantation of Au and Ag ions. The TiN films deposited by DC reactive sputtering were sequentially implanted with 200 keV gold ions at fluences of 0.5 × 1016 and 1 × 1016 ions/cm2 and 150 keV silver ions at fluences of 1 × 1016, 2 × 1016, 3 × 1016, and 4 × 1016 ions/cm2. Formation of spherical-like particles with dimensions below 10 nm, homogeneously distributed along the ion track of implanted ions is verified by high resolution transmission electron microscopy. Specific nanostructure containing Au Ag alloy in the center of the particle and only silver on the periphery was found in the TiN sample sequentially implanted with 1.0 × 1016 ions/cm2 of Au and 4 × 1016 ions/cm2 of Ag using high angle annular dark field scanning electron microscopy together with elemental mapping analysis. On the other hand, for the sample implanted with 0.5 × 1016 ions/cm2 of Au and 4 × 1016 ions/cm2 of Ag only formation of Au Ag alloy was observed. A mechanism for the formation of a new type core/shell nanostructure in ion implanted TiN thin films is proposed. By varying the implantation fluence of the gold and silver ions properly, the optimized experimental parameters for creation of a specific AuAg@Ag core/shell nanoparticles were achieved. • TiN films were implanted sequentially with Au and Ag ions at different fluences. • Formed nanostructures are influenced by gold ion fluence. • The formation of spherical like nanoparticles below 10 nm is identified. • Au Ag alloy nanoparticles were obtained using lower concentration of gold ions. • A new AuAg@Ag core/shell nanostructures were formed with higher Au concentration. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fabrication of fully relaxed Ge nanolayers using a new nanotechnology process based on epitaxy, condensation and microholes nanopatterning. Dynamic morphological and elastic evolution of the films are determined and explained thanks to elasticity and phase field models. • The results should play an important role to resolve and pass decisions on innovative Si based photonic devices which have achieved little progress during the last years (i.e. Ge-based photodevices). The films should also serve as platform for heterogeneous integration on Si. The process has been developed for an archetypical system, but the outcomes are generic and can be exploited for many other systems. Superior properties for complex photonic integrated circuits can be obtained by materials other than silicon but compatible with established silicon electronics, e.g., germanium. In this work, we demonstrate the integration with silicon of fully relaxed germanium-on-insulator nanolayers enabled by micro-holes patterning. The heterosystems are fabricated thanks to the combination of epitaxy, electron beam lithography, and condensation. High resolution transmission electron microscopy and geometrical phase analyses show that for holes patterning with periodicities lower than 1 µm, the germanium nanolayers are fully relaxed and free of extended defects, while having numerous defects for larger periodicities and unpatterned settings. The experimental results are discussed with the aid of calculations of the stress for coherent epitaxial silicon–germanium layer with finite size effects and phase-field simulations accounting for the morphological evolution of the germanium crystals. The fabrication method presented here enables the growth of thick monocrystalline germanium-on-insulator layers, with great potential for optoelectronic devices with tunable dimensions and high quality. Also, these systems are suitable for high-speed germanium-on-Si photodetectors with enhanced quantum efficiency resulting from light manipulation by the array of holes. This innovative system, which is expected to operate at the visible and near-infrared range of wavelengths, has huge potential for cutting-edge applications where photodetectors and bipolar transistors are integrated into the same wafer e.g. facial recognition and LIDAR. [ABSTRACT FROM AUTHOR]

Abstract Evolution of the structure and surface morphology of thin films composed of two selenium based chalcogenide phases, AgInSe 2 and Ag 2 Se on 140 MeV ion irradiation is reported. At this high energy, the projectile Ni ions sputtered the surface of the films through energy deposition to the target electrons. The sputtering led to decrease of silver and selenium concentration, but did not affect indium concentration. Surface analysis by field emission scanning electron microscopy study revealed nanoparticles of widely varying shapes and sizes on the surface of the films. Irradiation did not affect the particle size distribution which peaked at ~100 nm. The two phases, AgInSe 2 and Ag 2 Se exhibited different sensitivity to 140 MeV Ni ion irradiations. While Ag 2 Se phase was insensitive, the AgInSe 2 phase showed complex structural modifications at intermediate fluences, finally getting amorphized at high ion fluences. Analysis of the fluence dependence of Grazing Incidence X-ray Diffraction (GIXRD) peak area of AgInSe 2 phase indicated that each ion that penetrated the film, created an amorphous column of 1.6 nm radius. Surrounding the amorphous column, a cylindrical crystalline AgInSe 2 region of radius 8.2 nm, but with reduced lattice parameters formed. High resolution transmission electron microscopy image also confirmed registration of amorphized tracks and the modified crystalline region of similar radii around the path of 140 MeV Ni ions in a grain of AgInSe 2 as obtained from GIXRD study. Highlights • Ion irradiation induced sputtering rate of Ag, In and Se in the films depends on their initial concentration. • Ag 2 Se phase is insensitive while AgInSe 2 phase shows complex structural modifications under 140 MeV Ni ion irradiation. • A compressed crystalline region forms surrounding an amorphous column along the path of each ion in AgInSe 2. [ABSTRACT FROM AUTHOR]

Abstract We present an experimental study combined with first-principle methods and the chemical approach to characterize NiO surfaces. The comparison of two simulated surfaces, the apolar (100) and the polar (111) surfaces, allows to better differentiate their reactivity and their electronic properties. The redox chemistry upon the adsorption of different gases such as H 2 and H 2 O on pure and defective surfaces is also considered. The synthesized NiO nanoparticles obtained from triethylamine have plate-like morphologies with a crystalline size of 11 nm and the (111) surface, being the basal plane. This dominant surface is the most reactive one, it is hydroxylated at room conditions. Theoretical results confirm that the (111) surface is also likely to be hydroxylated under catalytic conditions for alkane oxidative dehydrogenation (ODH). The (001) surface at the opposite does not adsorb H 2 and is dehydroxylated. This apolar surface is not expected to be reactive. The results enable an interpretation of the high reactivity of the catalyst regarding morphological data provided by SEM (scanning electron microscopy) and HRTEM (high resolution transmission electron microscopy). Graphical abstract Unlabelled Image Highlights • Simulations enable to distinguish the structural and electronic properties of the nonpolar NiO(001) and polar NiO(111). • The dissociative adsorption of H 2 O and H 2 occurs on the clean (111) surface and on defects. • NiO was prepared from triethylamine and characterized by XRD, IR, SEM and TEM. • Plate-like nanoparticles with basal (111) surface are highly reactive for propane conversion. [ABSTRACT FROM AUTHOR]

Highlights • Electronic structure of Pt/Fe/Pt(1 1 1) model catalyst surface is altered by its subsurface Fe atoms. • Adsorption strength of H 2 O is less influenced by the altered electronic structure, relative to that of O 2. • Selective adsorption of trace H 2 O over O 2 is observed in the spectra of high resolution electron energy loss spectroscopy. Abstract The selective adsorption of trace water over O 2 is reported on Pt/Fe/Pt(1 1 1) surface of Pt-Fe model catalysts by using high resolution electron energy loss spectroscopy (HREELS). The Pt/Fe/Pt(1 1 1) surface has a sandwich structure of the topmost Pt atomic layer, subsurface Fe layer and underlying Pt(1 1 1) bulk, and presents the lower density of states (DOS) at 0–2.0 eV below the Fermi level with reference to Pt(1 1 1). On the Pt/Fe/Pt(1 1 1) surface the chemisorption of both O 2 and H 2 O would be weakened with different extents, which would change the relative order of their adsorption strength. At 105 K and exposure to O 2 with 0.1% v/v water, chemisorbed water species are dominated on the Pt/Fe/Pt(1 1 1) surface, while chemisorbed O 2 species are dominated on Pt(1 1 1) surface. The selective adsorption of trace water on Pt/Fe/Pt(1 1 1) surface could provide a hint that the well-tuned electronic structure of bimetallic catalysts might change the relative amount of surface species significantly and produce an influential effect on the CO reaction route at low temperatures. [ABSTRACT FROM AUTHOR]

The implantation-induced defects of crystalline silicon implanted with helium ions to a dose of 5 × 10 16 /cm 2 at 600 °C were investigated. The sample was analyzed by transmission electron microscopy and high-resolution electron microscopy. Faceted cavities are observed in the damaged layer. Concurrently the distribution of interstitial-type defect clusters was investigated by conventional electron microscopy in bright and dark field. Many rod-like defects, which belong to {1 1 3}, {1 1 1} and (−2 0 0), are formed in the end of the projected range. In front of the damaged layer, some ribbon-like defects are formed, which belong to 〈2 0 0〉, 〈1 −1 1〉 and 〈1 3 −3〉. The possible reasons of the observed defect clusters are discussed. [ABSTRACT FROM AUTHOR]

The paper presents a rational design of highly efficient and affordable catalysts for CO oxidation with a low operating temperature. A series of ceria-iron catalysts were inversely built via a co-precipitation method. The catalytic activity of low-temperature CO oxidation was much higher with CeO 2 -modified Fe 2 O 3 (CeO 2 Fe 2 O 3 ) than with Fe 2 O 3 -modified CeO 2 (Fe 2 O 3 CeO 2 ). In particular, the 7.5% CeO 2 Fe 2 O 3 catalyst had the highest activity, reaching 96.17% CO conversion at just 25 °C. Catalyst characterization was carried out to explore the cause of the significantly different CO conversion efficiencies between the Fe 2 O 3 CeO 2 and Fe 2 O 3 CeO 2 catalysts. HRTEM showed a significant inhomogeneous phase in 7.5% CeO 2 Fe 2 O 3 with small CeO 2 nanoparticles highly dispersed on the rod-shaped Fe 2 O 3 surface. Furthermore, the 7.5% CeO 2 Fe 2 O 3 composite catalyst exhibited the highest ratios of Fe 2+ /Fe 3+ and Ce 3+ /Ce 4+ as well as the largest pore volume. These properties are believed to benefit the CO conversion in 7.5% CeO 2 Fe 2 O 3 . [ABSTRACT FROM AUTHOR]

[Display omitted] • Nonlinear relationships between activities of Pt/CeO 2 and discharge time was found. • Pt particle size and oxygen vacancies can be regulated by controlling the discharge time. • Discharge time has a stronger impact on oxygen vacancy than Pt atom. • Pt/CeO 2 -PT5 demonstrated poor activity due to carbon deposition on the surface. This work demonstrated that a dielectric barrier discharge plasma was applied to modify the performance of catalyst. The Pt/CeO 2 catalyst was treated with various plasma discharge time to reveal the effect of plasma on the performance of Pt/CeO 2 catalyst for toluene oxidation. It is interesting that two volcanic peaks appeared at discharge time of 30 min (Pt/CeO 2 -PT3) and 3 h (Pt/CeO 2 -PT6). Compared to Pt/CeO 2 without plasma treatment, their catalytic activities (T 90) decreased by 24 °C for Pt/CeO 2 -PT3 and 34 °C for Pt/CeO 2 -PT6, respectively. By contrast, the Pt/CeO 2 -PT5 (2 h) showed the lowest activity due to the surface carbon deposition. We demonstrated that the plasma discharge time significantly affects the Pt particle size, CeO 2 -rod length, oxygen vacancies, and redox ability of the Pt/CeO 2 catalyst by using the characterizations of X-ray power diffraction patterns (XRD), specific surface area (BET), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and hydrogen temperature-programmed reduction (H 2 -TPR). The linear relationship between catalytic activities and turnover frequency values (TOF Pt and TOF Ov) were observed in the discharge time ≤1 h. Furthermore, we found that discharge time has a more profound impact on oxygen vacancy than Pt particle. [ABSTRACT FROM AUTHOR]

[Display omitted] • RuAlO hybird films were synthesized by alternating ALD sequences of Al 2 O 3 and Ru. • Nucleation delay was observed when Ru was deposited on Al 2 O 3 , not the other way. • With a low Ru cycle ratio, isolated Ru particles are embedded in the Al 2 O 3 matrix. • With a high Ru cycle ratio, Ru nucleus coalesce into a continuous film. • Electrical resistivity of the hybrid film could be adjusted over 10-3 ∼ 1011 Ω·cm. In this work, RuAlO hybrid films were synthesized by alternating ALD sequences of Al 2 O 3 and Ru for electrical conductivity regulation. O 2 exposure has significant effects on the nucleation and etching processes of Ru, therefore the O 2 exposure was first optimized for efficient growth of Ru. A set of RuAlO hybrid films with different Ru subcycle ratios were fabricated. In-situ quartz crystal microbalance (QCM) measurement revealed a certain nucleation delay when Ru was deposited on the surface of Al 2 O 3 , while no nucleation delay was observed when Al 2 O 3 was deposited on Ru. High resolution transmission electron microscopy (HRTEM) characterization confirmed formation of Ru grains embedded in amorphous Al 2 O 3 matrix. Elemental mapping results demonstrated that Ru and Al elements are uniformly distributed on the cross section of the film. In the grazing incidence angle X-ray diffraction (GIAXRD) patterns of RuAlO hybrid films, characteristic diffraction peaks of Ru appear with a Ru subcycle ratio ≥ 70 %. By properly tuning the Ru to Al 2 O 3 ALD subcycle ratio, electrical resistivity of the RuAlO hybrid film could be adjusted over a wide range of 10-3 ∼ 1011 Ω·cm. [ABSTRACT FROM AUTHOR]

[Display omitted] • We investigated the growth mechanism of MoO 2 on c- sapphire and achieved the orientation controlled preparation. • The crystal direction of MoO 2 was accurately judged. • Possible atomic models of epitaxial growth were proposed. • The crystal orientation of MoO 2 was rapidly determined by angle-resolved polarization Raman spectroscopy without damage. Identifying the crystallographic orientations and understanding the growth mechanism of MoO 2 nanocrystals are important for device applications. Here, we investigate the effect of precursor concentrations in chemical vapor deposition on the orientation of MoO 2 nanoflakes with respect to the substrate surface. X-ray diffraction, optical microscopy, (tilted) scanning electron microscopy, high resolution transmission electron microscopy, selected area electron diffraction, and angle-resolved polarized Raman spectroscopy were used to determine the crystal orientations of the nanoflakes and their epitaxial relationship with c- sapphire substrates: lying-down MoO 2 nanoflakes for MoO 2 (0 1 0)∥sapphire(0001) and MoO 2 <0 0 1>//sapphire< 1 1 ¯ 00 >, and standing-up ones for MoO 2 (1 0 0)∥sapphire(0001) and MoO 2 <0 0 1>∥sapphire< 1 1 ¯ 00 >. Tentative atomic epitaxial models are proposed to explain the orientation and alignment. The investigations also demonstrated that angle-resolved polarized Raman spectroscopy is a quick and nondestructive method to identify the crystallographic orientations of nanoflakes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel CVD process combining oxidation and annealing at ultra-low oxygen flow. • New elastic relaxation mechanism of dislocation-free SiGe on SiO2. • Strategy of fabrication of MOSFET devices an. • SiGe relaxed template layer for heterogeneous integration on Si substrate. We show that a newly developed high temperature, ultra-low rate oxidation process can produce homogeneous, fully strained, defect-free and perfectly flat Silicon Germanium (Si 1-x Ge x) On Insulator films when x ≤ 0.33. For larger Ge concentrations (x = 0.5), we evidence a new mechanism of elastic strain relaxation taking place through the undulation of the Si 1-x Ge x layer without nucleation of dislocations. In these experimental conditions (ultra-low rate oxidation at 1000 °C), strain relaxation proceeds through the slow diffusion and motion of matter at the Si 1-x Ge x /SiO 2 interface and not through dislocation nucleation. The mechanism results in the morphological evolution and local swelling of the SiGe embedded layer, facilitated by the viscous flow of SiO 2. At this temperature, the Si 1-x Ge x film expands in the viscous SiO 2 to minimize the strain energy. Geometric Phase Analysis of High Resolution Transmission Electron Microscopy cross-section images confirms that the lateral expansion leads to the relaxation of the strain accumulated during condensation of Ge. We suggest that this phenomenon could be at the origin of the buckling mechanism already reported in the literature. This study demonstrates that SiO 2 can serve as an efficient compliant substrate for strain engineering of defect-free Ge rich Si 1-x Ge x thin films. This new generic relaxation process based on viscoelasticity of SiO 2 matrix could be applied to many other systems beyond Si 1-x Ge x films. The high-quality defect-free Ge rich SGOI films fabricated here can act as good template for the heterogeneous integration of various 2D or 3D materials on Si substrate. [ABSTRACT FROM AUTHOR]

[Display omitted] • The oxide islands contain three types: hemispherical, disc-like and film-like. • EDS and SAED demonstrate the primary components of the oxide islands are amorphous SiO 2 , MnO, MnSiO 3 and Mn 2 SiO 4. • Surface diffusion and bulk diffusion dominate the geometry of the oxide islands. • Formation process of circular oxide nano-inclusions is discussed in detail. • An oxidation mechanism model is proposed based on experimental results. The characterization of the oxide islands on the surface of the spatter contributes to a fundamental understanding of the formation and oxidation of spatter in laser powder bed fusion (LPBF). In the present study, the surface and cross-section characteristics of spatters with oxide islands are investigated using high resolution scanning electron microscopy combined with energy dispersive spectroscopy, scanning transmission electron microscopy and selected area electron diffraction. The oxide islands with different configurations on the spatter surface are divided into three main categories: hemispherical, disc-like and film-like. Moreover, the primary component of oxide islands is an amorphous SiO 2 , which may also contain MnO, MnSiO 3 , and Mn 2 SiO 4. Furthermore, a transition layer (enriched in Si, Mn, and O) is found at the oxide islands || spatter substrate interface, and the width of which is 4 μm and 20 nm on the spatter surface and within the spatter cross-section, respectively. Besides, the composition and sources of the circular oxide nano-inclusions (50-600 nm) internal to the spatters are also discussed in detail. Eventually, the driving forces affecting the formation of oxide islands on the surface of spatters are summarized, and a schematic diagram of the formation procedure is developed. [ABSTRACT FROM AUTHOR]

[Display omitted] • As-deposited CoFeB/Mg(O) multilayers shows PMA with reactive sputtering. • The magnetic anisotropy shows close correlation with the composition ratio (ε) of Fe oxide to Fe at interface. • The film exhibits PMA when ε falls in 0.65 between 0.75, beyond it shows IMA. Ta (5)/CoFeB (1)/MgO (2)/Ta (2) (in nm) multilayers were deposited on silicon substrates by magnetron sputtering, and the MgO layer was prepared by two methods at the same argon gas flow rate: the radio frequency (RF) sputtering method of MgO target and the reactive sputtering method of direct current (DC) sputtering Mg target with introducing oxygen at the same time. The sample prepared by the former method was denoted as Sample A, and the latter was denoted as Sample B. The results indicate that as-deposited Sample A shows in-plane magnetic anisotropy (IMA) with K eff = -0.79 × 106erg/cm3. However, the as-deposited Sample B shows perpendicular magnetic anisotropy (PMA) with K eff = 1.69 × 106erg/cm3, and the K eff value increases to 3.17 × 106erg/cm3 after annealing at 250℃. X-ray photoelectron spectroscopy (XPS) results illustrate that the films show PMA when the composition ratio (ε) of Fe oxide to Fe in CoFeB/oxide interface of Sample A and B annealed below 300 ℃, is approximately in the range of 0.65–0.75. When ε is beyond the above range, the film shows IMA. Moderate oxidation state at the interface results in the formation of PMA and it was improved by forming effective orbital hybridization of Fe 3d and O 2p. High resolution transmission electron microscopy (HRTEM) analysis reveals that no crystallization appears in CoFeB and MgO layer of the film before and after annealing, and crystallization has no effect on the interface chemical states in this system. [ABSTRACT FROM AUTHOR]

The selective deoxygenation of aldehydes and alcohols without cleaving the C C bond is crucial for upgrading bio-oil and other biomass-derived molecules to useful fuels and chemicals. In this work, propanal, 1-propanol, furfural and furfuryl alcohol were selected as probe molecules to study the deoxygenation of aldehydes and alcohols on molybdenum carbide (Mo 2 C) prepared over a Mo(1 1 0) surface. The reaction pathways were investigated using temperature programmed desorption (TPD) and high resolution electron energy loss spectroscopy (HREELS). The deoxygenation of propanal and 1-propanol went through a similar intermediate (propoxide or η 2 (C,O)-propanal) to produce propene. The deoxygenation of furfural and furfuryl alcohol produced a surface intermediate similar to adsorbed 2-methylfuran. The comparison of these results revealed the promising deoxygenation performance of Mo 2 C, as well as the effect of the furan ring on the selective deoxygenation of the C O and C OH bonds. [ABSTRACT FROM AUTHOR]

[Display omitted] • The role of CNT in promoting crystallinity of composites. • Morphological and structural changes upon thermal treatment. • BiOI together with other phases enhanced photocatalytic activity. • BiOI/CNT composites showed higher photocatalytic activity for phenol and RhB. • Photocatalytic activity is dependent on synthesis, crystallinity and BiOI phases. In this work, we have prepared BiOI/CNT composites by hydrothermal method and studied the impact of CNT and hydrothermal treatment conditions (temperature and time) simultaneously on phenomena such as crystallization. The samples were studied using X-ray Diffraction (XRD), nitrogen sorption (Brunauer–Emmett–Teller (BET) specific surface areas), Scanning Electron Microscopy assisted with Energy Dispersive X-Ray spectroscopy (SEM-EDX), High Resolution Transmission Electron Microscopy (HRTEM), UV–vis Diffuse Reflectance spectroscopy (DRS), Raman spectroscopy and photoluminescence spectroscopy (PL). The different heat treatments applied and varied amount of CNT was found to have a profound effect on the structural, morphological, compositional and optical properties of the prepared composites. The distinguishable changes in the above-mentioned properties were clearly visible for the samples prepared at higher temperature and longer duration (150 °C, 6.30 h). Surprisingly, the presence of other phases of BiOI, such as Bi 7 O 9 I 3 , Bi 4 O 5 I 2 , Bi 5 O 7 I, also co-existed at the same time, although in low amount. Finally, for the study, the photocatalytic efficiency of the prepared samples was tested for phenol and RhB, as model pollutants, under visible light irradiation for 240 min and 120 min, respectively. The results revealed that the composites prepared at higher temperature with longer duration showed superior performance for the photodegradation of phenol and RhB. Additionally, the composites performed better than their respective reference samples in each case. Interestingly, the introduction of CNT promoted the crystallinity in the composites and promising results for the removal of phenol and RhB were achieved by the use of low power ordinary visible lamps. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of reduced graphene oxide assisted two-dimensional graphitic ZnO. • Polarisation dependent x-ray absorption spectroscopy to identify 2D phase. • Electronic structure using ligand field theory. • Density Functional Theory simulated relaxed 2D ZnO structure as initial model for EXAFS analysis. Reduced graphene oxide (rGO) assisted two-dimensional (2D) graphitic ZnO (gZnO) have been prepared and characterized by Raman, FTIR, Cross-sectional high resolution transmission electron microscopy (HRTEM) and X-ray absorption spectroscopy (XAS) techniques comprising of X-ray near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) measurements. Raman spectroscopy and FTIR measurements suggest formation of ZnO and the same has been corroborated by XANES measurements. HRTEM and polarization dependent XANES measurements with two different sample orientations confirm the formation of gZnO/rGO sandwiched layers. Density Functional Theory simulated relaxed initial structure of bilayers of gZnO sandwiched between successive rGO layers fits the EXAFS data reasonably well, supported by formation energy calculations which indicate better stability for samples having bilayers to a few layers of gZnO between rGO layers than with monolayer. These relaxed structures also help to understand the electronic structure contributing in XANES spectrum, with the help of ligand field theory. [ABSTRACT FROM AUTHOR]

Abstract: The in-depth distribution of hydrogen atoms in 100nm-thick, amorphous-nanocrystalline, silicon films (a-nc-Si:H) was estimated by time-of-flight elastic recoil detection analysis (TOF-ERDA) using a previously described set-up. The layer with nanocrystals was deposited on a 50nm amorphous layer by plasma-enhanced chemical vapor deposition (PECVD), using silane gas that was diluted with hydrogen. High-resolution transmission electron microscopy (HRTEM) showed that the films contained nanocrystals of silicon embedded in an amorphous Si:H matrix. The size of the nanocrystals and the crystal-to-amorphous ratio increased in the direction from the substrate toward the surface of the film. The amorphous matrix appeared uniform, except for the area close to the a-Si:H/a-nc-Si:H interface, where spots that were brighter than average appeared. These areas can be attributed to the presence of less-dense material, presumably voids. It is assumed that the surface of the voids is “decorated” with hydrogen that saturates the silicon “dangling bonds”. This is why the distribution of hydrogen should indicate a density fluctuation in the material. Consistent with this assumption, the TOF-ERDA showed a non-uniform distribution of hydrogen across the depth, with a maximum value close to the a-Si:H/a-nc-Si:H interface that coincides with the less-dense material seen by the HRTEM. This supports the idea about the important influence of voids on crystal formation, particularly in the nucleation phase. After a heat treatment at 400°C, the distribution of hydrogen remained the same, while the total hydrogen concentration decreased. This indicated that the type of hydrogen bonding was the same across the amorphous network and assumed that the areas of less-dense material are agglomerates of smaller voids. [Copyright &y& Elsevier]

Abstract: Precise knowledge of the atomic and electronic structure of scanning tunneling microscopy (STM) tips is crucial for a correct interpretation of atomically resolved STM data and an improvement of the spatial resolution. Here we demonstrate that tungsten probes with controllable electronic structure can be fabricated using oriented single crystalline tips. High quality of the [001]-oriented W tips sharpened in ultra high vacuum was proved by electron microscopy. Distance dependent STM studies carried out on a graphite (0001) surface demonstrate that application of crystallographically oriented single crystalline tips allows one to control the tip electron orbitals responsible for high resolution imaging under specific tunneling conditions. [Copyright &y& Elsevier]

Abstract: Branched rutile TiO2 nanorod arrays were directly synthesized on the F-doped tin oxide (FTO) substrate through a two-step hydrothermal treatment by a seeding method with TiO2-nanorods as seeds. The samples were characterized respectively by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and field-emission scanning electron microscopy (FESEM). Results showed that TiO2 nanorods with nanobranches (TiO2-NB) grew vertically on the FTO substrate. XRD and HRTEM results confirmed that the TiO2-NB arrays were single-crystalline rutile. The optical properties of the samples were studied with a UV–vis spectrometer. The photocatalytic activity of the TiO2-NB film is better than that of P25 particulate film. Direct electrical pathway and improved light-harvesting efficiency were crucial for the superior photocatalytic activity of the TiO2-NB arrays. [Copyright &y& Elsevier]

Abstract: Well-aligned single crystalline zinc oxide (ZnO) nanorods were successfully grown, by hydrothermal synthesis at a low temperature, on flexible polyethylene terephthalate (PET) substrates with a seed layer. Photoluminescence (PL), field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) measurements were used to analyze the optical and structural properties of ZnO nanorods grown for various durations from 0.5h to 10h. Regular and well-aligned ZnO nanorods with diameters ranging from 62nm to 127nm and lengths from 0.3μm to 1.65μm were formed after almost 5h of growth. The growth rate of ZnO grown on PET substrates is lower than that grown on Si (100) substrates. Enlarged TEM images show that the tips of the ZnO nanorods grown for 6h have a round shape, whereas the tips grown for 10h are sharpened. The crystal properties of ZnO nanorods can be tuned by using the growth duration as a growth condition. The XRD and PL results indicate that the structural and optical properties of the ZnO nanorods are most improved after 5h and 6h of growth, respectively. [Copyright &y& Elsevier]

Abstract: We report on the fabrication of single phase of the Si(111)-(√31×√31)–In reconstruction surface, observed by scanning tunneling microscopy (STM) at room temperature. By depositing specific amounts of indium atoms while heating the Si(111)-(7×7) substrate at a critical temperature, the single phase of Si(111)-(√31×√31)–In surfaces could be routinely obtained over the whole surface with large domains. This procedure is certified by our high-resolution STM images in the range of 5–700nm. Besides, the high resolution STM images of the Si(111)-(√31×√31)–In surface were also presented. [Copyright &y& Elsevier]

Schematic of Hydrogen Plasma Treatment (HPT) and the high resolution transmission electron microscopy image of the HPT treated a-Si:H/ Si interface. [Display omitted] • Comparison of different H 2 plasma treatments to enhance Si surface passivation. • Passivation mechanism of hydrogen plasma treated aSi:H elucidated using FTIR & HRTEM. • Demonstration of hydrogen plasma treatment on ultra-thin 5 nm amorphous Si layer. • Developed state of the art passivation by two stage intermediate and post HPT. • Degradation study in passivation of HPT aSi:H/Si in ambient conditions with time. Defect engineering of amorphous-crystalline silicon interface is a critical aspect for high efficiency silicon heterojunction solar cells. In this work, we have done a comparative study of different hydrogen plasma treatment (HPT) methods namely Pre, Post and Intermediate (Inter) HPT using radio frequency plasma-enhanced chemical vapor deposition (rf-PECVD) to understand the passivation mechanism to obtain state of the art passivation. It was observed that Inter and Post HPT can give high minority carrier lifetime on both p and n type wafers and has lesser interface defect states. The analysis from Fourier Transform Infrared Spectroscopy and high resolution Transmission Electron Microscopy shows that these HPT methods results in higher bulk disorder yet atomically sharp and superior interface due to hydrogen diffusion which saturates the interface dangling bonds. While a Pre-HPT results in epitaxial growth leading to poorer performance inspite of lowest dihydrides in the bulk which further highlights the importance of the interface. We have demonstrated Inter and Post HPT of ultrathin (5 nm) a-Si:H films which could give surface recombination velocity as low as 13 cm/s. The degradation due to hydrogen effusion in these HPT a-Si:H films has also been studied. [ABSTRACT FROM AUTHOR]

Abstract: GaN nanowires and nanorods have been successfully synthesized on Si(111) substrates by magnetron sputtering through ammoniating Ga2O3/V films at 900°C in a quartz tube. X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectrum were carried out to characterize the structure, morphology, and photoluminescence properties of GaN sample. The results show that the GaN nanowires and nanorods with pure hexagonal wurtzite structure have good emission properties. The growth direction of nanostructures is perpendicular to the fringes of (101) plane. The growth mechanism is also briefly discussed. [Copyright &y& Elsevier]

Abstract: This work reports the morphological investigation of nanostructured sulfided CoMo catalysts by means of high-resolution transmission electron microscopy (HRTEM). The catalysts were supported on Ti-modified hexagonal mesoporous silica (HMS-Ti) and P-modified HMS-Ti (P/HMS-Ti) materials. The oxide precursors were characterized by specific surface area (SBET), temperature-programmed reduction (TPR), diffuse reflectance infrared Fourier transform spectroscopy in the OH region (DRIFTS-OH) and X-ray photoelectron spectroscopy (XPS) in order to elucidate the influence of the impregnation sequence (successive vs. simultaneous) and the effect of P-incorporation into HMS-Ti material on the morphology of calcined CoMo catalysts. Both TPR and XPS measurements indicate that the catalysts prepared by successive impregnation possess well-dispersed MoO3 and CoO phases, whereas their counterparts prepared by simultaneous impregnation additionally possess the CoMoO4 phase. For all sulfided catalysts, the presence of MoS2 phase with particle size in the range 3.3–4.4nm was confirmed by HRTEM. Catalytic activity was evaluated in the reaction of hydrodesulfurization (HDS) of dibenzothiophene (DBT) carried out in a flow reactor at 593K and hydrogen pressure of 5.5MPa. P-incorporation into the HMS-Ti material led to an overall increase in HDS activity and the hydrogenation ability of the sulfided catalysts. All catalysts proved to be stable during 10h time-on-stream (TOS) operation. The activity of sulfide catalysts in the target reaction depends linearly on the surface exposure of Co species in the oxide precursors, as determined by XPS, and on the morphology of the sulfide form of catalysts (surface density of MoS2 particles and their sizes) as determined by HRTEM. [Copyright &y& Elsevier]

Abstract: The effects of Ar microwave plasma treatment on field emission properties of the printed carbon nanotubes (CNTs) cathode films using Ag nano-particles as binder were investigated. The field emission J–E characteristics were measured at varied plasma treatment time. Significant improvement in emission current density, emission stability and uniformity were achieved for the Ar treated CNTs films, even though the plasma treatment increased the turn on electric field slightly. High-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy revealed the microstructural changes of CNTs after the plasma treatment. The improved field emission properties of CNTs film can be attributed to the generation of a high density of structural defects after treatment, which increased greatly the possible emission active sites. Besides, the formation of the sharpened and open-ended CNTs tips is all helpful for improving the field emission properties of the treated CNTs. [Copyright &y& Elsevier]

Abstract: The adsorption of diethylamine (DEA) on Si(100) at 100K was investigated using high-resolution electron energy loss spectroscopy (HREELS) and electron stimulated desorption (ESD). The thermal evolution of DEA on Si(100) was studied using temperature programmed desorption (TPD). Our results demonstrate DEA bonds datively to the Si(100) surface with no dissociation at 100K. Thermal desorption of DEA takes place via a β-hydride elimination process leaving virtually no carbon behind. Electronic processing of DEA/Si(100) at 100K results in desorption of ethyl groups; however, carbon and nitrogen are deposited on the surface as a result of electron irradiation. Thermal removal of carbon and nitrogen was not possible, indicating the formation of silicon carbide and silicon nitride. [Copyright &y& Elsevier]

Abstract: The microstructure of interfaces between powder particles in Al–Mg alloy specimens sintered by pulse electric-current sintering (PECS) process was characterized using high resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDS). The crystalline precipitates with nano-size in the interface were observed in all of Al–Mg alloy specimens. The composition was determined to be MgAl2O4 or MgO, or both of them, which depended on Mg content in alloy powder and sintering temperature. The precipitates were suggested to contribute to reduction reaction of Mg with oxide films originally covered at powder particles surface. [Copyright &y& Elsevier]

Abstract: Nanometer-sized Xe particles embedded in Al are observed with an off-Bragg condition high resolution transmission electron microscopy. It is found that a Xe particle with size of about 1nm shows quite different structural properties from those with larger sizes. It changes structure from an f.c.c. to another one, changes orientation with the same f.c.c. structure, or changes shape and sizes. These changes are attributed to (1) a high mobility of atoms on Xe/Al interface due to irradiation of 1MeV electron beam and irradiation enhanced interfacial diffusion; (2) a smaller barrier in energy for shape change of a smaller Al void where the Xe particle is constrained; (3) a larger fraction of atoms on Xe/Al interface for a smaller Xe particle. [Copyright &y& Elsevier]

Abstract: The ordered arrays of Au nanoparticles were fabricated by electron-beam-induced selective deposition process in an ordered pore arrays of anodic porous alumina membrane. The microstructure of the as-deposited nanoparticles was characterized using high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDS) and microdiffraction technique. It was determined that the as-deposited nanoparticles consisted of many nanocrystallites of Au metal. The size of these nanocrystallites in the as-deposited nanoparticles was smaller than 5nm. [Copyright &y& Elsevier]

Abstract: Interfacial atomic structures of Cu/Al2O3(0001) and Cu/Al2O3() prepared by the pulsed-laser deposition technique were characterized by high-resolution transmission electron microscopy (HRTEM). It was found that (111) and (001) planes of Cu were epitaxially oriented to Al2O3(0001) and Al2O3() planes, respectively. Chemical bonding states at the interfaces were analysed by electron energy-loss spectroscopy (EELS). In oxygen–K edge energy-loss near-edge structure (O–K ELNES) of the Cu/Al2O3(0001) and Cu/Al2O3() interfaces, a shoulder peak appeared at the lower energy side of the main peak. This indicates that Cu–O interactions were formed across these Cu/Al2O3 interfaces. In fact, the simulated HRTEM images based on the O-terminated interface models agreed well with the experimental ones. It can be concluded that the O-terminated interfaces were formed in the present Cu/Al2O3 interfaces. [Copyright &y& Elsevier]

Abstract: Al2O3 bicrystals containing [0001] symmetric tilt Σ7 grain boundaries with different grain boundary planes of {410} and {210} were fabricated by diffusion bonding, and the grain boundary structures were investigated by high-resolution transmission electron microscopy (HRTEM). From HRTEM observations combined with atomistic simulations, it was found that the grain boundaries exhibited characteristic atomic arrangements, and the Σ7/{210} boundary contained large open spaces at its core. In compressive creep experiments for the bicrystals, these boundaries showed quite different creep behavior, although they have the same Σ value. The measured sliding rate of Σ7/{210} was much larger than that of Σ7/{410}, which may be due to the open core structure formed in Σ7/{210}. [Copyright &y& Elsevier]

Abstract: The atomic structures of crack walls due to cleavage fracture in silicon nitride (Si3N4) and magnesium oxide (MgO) have been investigated by in situ straining transmission electron microscopy (TEM) and high-resolution electron microscopy (HREM) at room temperature. In the case of Si3N4, the crack walls on the (100) plane were atomically flat, which indicates that the crack propagated along a particular crystal plane without deflection. On the other hand, the cleaved crack walls in MgO were not atomically flat but contained a number of square-shaped steps with a few {010} atomic layers in height. Thus, it can be said that the cleavage crack was deflected at the atomic level during its rapid propagation. The origin of their step structures is discussed using results from molecular dynamics (MD) simulations. [Copyright &y& Elsevier]

[Display omitted] • Structural characterization Iron doped Na 2 Ti 2 O 5 ·H 2 O titanate nanotube. • Morphological and structural characterization of Fe doped titanate nanotube. • Computational simulations of structural, vibrational and optical properties. • Red shift in the band gap of about 0.2 eV upon iron doping. In this work we present the synthesis, optical and electrical characterization of nanoparticles of iron doped anatase and iron doped sodium titanate high aspect ratio nanostructures (Na 2 Ti 2 O 5 ·H 2 O). Our study focused mainly in the study of the electronical structure and the derived properties of the dielectric function by DFT (Density Functional Theory) means and their relationship with experimental measurements of optical band gap and electric impedance spectroscopy. Also, structural and morphological characterizations of the systems were carried on by X-ray powder diffraction, high resolution transmission electron microscopy and Raman spectroscopy. It was possible for the doped nanostructures to observe a slight red shift in the band gap of about 0.2 eV and an order of magnitude decrease in the global resistance in the doped system. [ABSTRACT FROM AUTHOR]

• Fabrication of Al 2 O 3 /Ge/(Al 2 O 3 /SiO 2)/Si memory structures by magnetron sputtering. • Structural and memory properties analysis of annealing effects in wide temperature range. • Transition from amorphous to Ge NCs at 700 °C and to GeAl mixed oxide NCs at 800 °C. • Memory window increase up to 5.4 V at 600 – 700 °C by charge storage centers evolution. • Memory retention with only 5% decrease of memory window after 104 s monitoring. In this paper, we report studies on Al 2 O 3 /Ge/Al 2 O 3 trilayer memory structures deposited by magnetron sputtering at room temperature on p-Si substrates coated with 3 nm SiO 2. The changes of the structure, morphology and memory properties induced by rapid thermal annealing (RTA) in a broad temperature range 550–900 °C have been carefully investigated. High resolution transmission electron microscopy (HRTEM) revealed the existence of distinct RTA effects for different temperature ranges, in correlation with memory properties measured on Al/Al 2 O 3 /Ge/Al 2 O 3 /SiO 2 /p-Si/Al devices. Thus, at temperatures smaller than 650 °C, Ge diffuses into adjacent Al 2 O 3 , the layers remaining amorphous. The memory window increases from as-deposited samples to those annealed at 600 °C reaching the maximum of 5.4 V. After RTA at 700 °C, Ge nanocrystals (NCs) in intermediate Ge layer and Ge-rich amorphous nanoparticles in Al 2 O 3 tunnel oxide are formed. Increasing RTA temperature to 800 and 900 °C, Ge NCs are no longer formed due to Ge strong diffusion. Instead, Ge-rich mixed GeAl oxide NCs of unknown crystalline structure are evidenced by HRTEM. The memory window continuously decreases with annealing temperature in the range 650–900 °C. The ON (OFF) charge loss of only 11% (9.8%) was found by extrapolation to 10 years. [ABSTRACT FROM AUTHOR]

• Estimating the width of crystalline-amorphous interface transition region using high resolution images. • Molecular dynamics (MD) modeling of the irradiation process. • Simulation of high-resolution images closely matching the experimental ones. • Introduction of the displacement order parameter. • Evaluating the interface transition region width from the calculated atomic positions. Application of ion beams in modern technology requires quantifying disorder induced by the collisions of energetic species and substrate atoms. For studying the structure of the transition region between crystalline silicon and amorphous layer Si(0 0 1) substrate was bombarded by gallium ions with the energy of 5 keV. The transition region width and amorphous layer thickness were evaluated using cross-correlation analysis of high- resolution electron microscopy (HRTEM) images taken from cross-section specimens. Performed molecular dynamics simulations allowed obtaining atom positions in amorphized material, which provided close agreement between the simulated and experimental HRTEM images. Analysis of calculated atomic arrangements realized by employing an introduced displacement order parameter enabled finding the interface transition region width and amorphous layer thickness which agreed satisfactorily with the values estimated from HRTEM images. This agreement gives evidence that MD simulation can be applied for reliable prediction and quantification of the disordered region extension in the ion bombarded material. The obtained amorphous layer thickness is also consistent with the results established utilizing the critical point defect density model applied to Monte Carlo simulations. [ABSTRACT FROM AUTHOR]

The effect of Sr and Ag co-implantation and recovery annealing on the structural, mechanical and electrical properties of glassy carbon is reported. Glassy carbon was co-implanted with 200 keV Sr and Ag ions to a fluence of 1 × 1016 ions/cm2 at room temperature. Combination of Raman spectroscopy and high resolution transmission electron microscopy (HRTEM) showed that the co-implantation of Sr and Ag resulted in amorphisation of the glassy carbon substrate. Raman spectra and HRTEM micrographs obtained after annealing indicated recovery of the glassy carbon structure, however, the recovered structure appears to be graphite-like. Instrumented indentation experiments on the ion-irradiated glassy carbon substrates revealed the formation of a surface layer with considerably enhanced mechanical performance. When annealing the ion implanted samples, these effects were only partially reversible. The effect of the irradiation-induced amorphisation and graphitisation of glassy carbon on its conductivity was also studied. The sample became less conductive after Sr and Ag co-implantation, whereby annealing resulted in an increase in conductivity. [ABSTRACT FROM AUTHOR]

• We report the influence of RGO on electrochemical properties of CeO 2 /Ce 2 O 3 quantum dots. • The composite of CeO 2 /Ce 2 O 3 containing 7 wt% RGO (CRGO7) exhibited the best performance. • CRGO7 exhibited specific capacitance of 1027 F/g at 1 A/g with 79% cycling stability @5000 cycles. • The above performances are better than all previous CeO 2 and RGO based electrodes. • Synergistic effects of RGO and highly catalytic CeO 2 /Ce 2 O 3 resulted in the improvement. Herein, we report a simple hydrothermal method to synthesize CeO 2 /Ce 2 O 3 quantum dots anchored on reduced graphene oxide (RGO) sheets of different weight fractions for application as supercapacitor electrode. Of all the tested samples, the one containing 7 wt% RGO (CRGO3) as measured by thermogravimetry, exhibited the highest specific capacitance of 1027 F/g at 1 A/g along with good cycling stability. At current density of 4 A/g, the CRGO3 sample showed charge retention of 79% after 5000 cycles, whereas at 20 A/g, it showed 85% charge retention after 3000 cycles. The values obtained for CRGO3 electrode are better than all previous ceria and RGO based electrode suggesting its potential use in supercapacitor. High resolution transmission electron microscopy (HRTEM) revealed well crystalline CeO 2 nanoparticles (~5 nm) uniformly distributed on the RGO sheets as well as few lattice planes indicative of presence of some Ce 2 O 3 mixed with CeO 2. X-ray photoelectron spectroscopy (XPS) revealed presence of a mixed oxides containing mostly CeO 2 with some Ce 2 O 3 phase on the surface. The enhanced performance of the CRGO3 electrode was attributed to the optimized weight fraction and large surface area of electrically conducting RGO combined with enhanced electrocatalytic activity of CeO 2 /Ce 2 O 3 mixed oxides. [ABSTRACT FROM AUTHOR]

• The catalytic activity of Co 3 O 4 /γ-Fe 2 O 3 catalyst to NO + CO reaction was higher than that of the two components alone. • Electron transfer interaction exists between γ-Fe 2 O 3 and Co 3 O 4. • The NO + CO reaction activity of the magnetized catalyst at low temperature is better than that of the unmagnetized catalyst. • Magnetized Co 3 O 4 /γ-Fe 2 O 3 catalyst can exert a strong adsorption effect on NO through the magnetic field. In this study, a series of catalysts, supported by γ-Fe 2 O 3 and with different concentrations of Co 3 O 4 as active components, were prepared by impregnation method for selective catalytic reduction (SCR) of NO by CO. The catalysts were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), H 2 temperature programmed reduction (H 2 -TPR), vibrating sample magnetometer (VSM), in situ infrared diffuse reflectance spectroscopy (in situ DRIFTS). The possible mechanism of catalysts in NO + CO reaction was proposed. The results show when the molar ratio of Co 3 O 4 to γ-Fe 2 O 3 is 20:45, the catalyst has the best N 2 yield in NO + CO reaction, it is because the two metal oxides have the strongest interaction at this ratio and can produce more oxygen vacancies on the surface and improve the oxygen storage capacity. After a period of magnetization, it showed better catalytic performance than before, because the magnetized catalyst can absorb additional paramagnetic gas like NO. Finally, based on the results of in-situ infrared spectroscopy, a possible mechanism is proposed, showing that the reaction conforms to the L-H mechanism. [ABSTRACT FROM AUTHOR]

• Analysis of morphology, micro and nanostructure of biocomposite LYS/MCF surface. • Weakening of hydrogen bonds in the secondary structure upon protein adsorption. • Diminishing of pore sizes by LYS molecules packed inside the pores (XRD, AFM). • Homogenous distribution of C, O, N, S on the protein/silica surface (EDX mappings). • MCF-LYS interactions clearly seen on XPS spectra. The results presented in this paper focus on a detailed analysis of surface composition, texture, morphology and micro-nanostructure of mesocellular silica foam (MCF) covered by the lysozyme (LYS) molecules from aqueous solutions at pH = 7.4. The physicochemical and structural properties of the LYS/MCF biocomposite were characterized by various techniques including attenuated total reflection (ATR) Fourier transform infrared spectroscopy (FT-IR), elemental analysis (CHN), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (UV–Vis DRS), X-ray diffraction (XRD). Moreover, the morphology, micro-nanostructure, topography and elemental composition of biocomposite surface were determined using atomic force microscopy (AFM), optical profilometry (OP), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy with X-ray microanalysis (SEM/EDS). AFM, OP, TEM and SEM methods (with regard to morphology, topography, structure at a micro-nanometer level) demonstrate that the surface of the support with immobilized protein is less rough, porous, wavy, sharp, and hence more smooth, flat and uniform due to the proteins adsorbed on support surface. EDX and EDS demonstrated the homogeneous distribution of protein molecules on silica surface. XRD confirmed that the lysozyme molecules were located on the support surface and inside the pores, and XPS revealed the specific interactions between the albumin and silica. [ABSTRACT FROM AUTHOR]

• Turning with slide diamond burnishing strongly refined the grain size of sub-surface layer. • Dense layer of surface TiN was formed in low temperature (~540 °C) 3 stage hybrid process. • Mechanism of TiN formation at low temperature GN was explained through microstructure. Gas nitriding is one of the more effective ways of improving wear and corrosion resistance of titanium alloys, but this treatment performed at a high temperature degrades their high specific strengths. Therefore, we have subjected a Ti-6Al-4V alloy to a hybrid multi-stage treatment including turning with slide burnishing followed by gas nitriding at temperature reduced down to 540 °C. The mechanical treatment introduces a large number of defects in the form of dislocations and grain boundaries—opening additional paths for nitrogen diffusion. High resolution electron microscopy shows that after such mechanical treatment the surface is covered with an amorphous tribo-film. Below the surface, to a depth of some 100 nm, a layer of elongated dislocation cells is seen. The latter was backed by a 500 nm thick layer of strongly defected laths. Gas nitriding at 540 °C caused at first a crystallization of the tribo-layer (after 8 h), producing a mixture of nitrides and oxides. Next, below a tribo-layer, a dense layer of the δ-TiN phase is formed, with a thickness of 5 nm and 50 nm after 16 h and 24 h, respectively. Application of slide burnishing and low-temperature gas nitriding causes an increase in surface hardness by 5–10 % without compromising the strength of the core material. [ABSTRACT FROM AUTHOR]

• Cyclic stress promotes local surface nanocrystallization of Zr-based BMG at RT. • Combined actions of indentation and cyclic rather than static stress induce crystallization. • Fatigue plastic work and elastic energy release promote the crystallization nearby indentation edge. Crystallization behaviors of bulk metallic glass (BMG) have been obtaining widespread concern, especially under service conditions including elevated temperature, electrical pulse, mechanical stress and high pressure. In this paper, cyclic stress was considered as typical service condition and applied on a Zr 55 Cu 30 Al 10 Ni 5 BMG specimen with prefabricated double V-notches. Through indentation tests on fatigue-fractured specimen along with the connection line between notch tips, diversities in indentation serrated flow behaviors and morphological anisotropies were directly observed. Through transmission electron microscopy (TEM) characterization and selected area electron diffraction (SAED) analysis of thinned BMG specimen adjacent to indentation edge, direct experimental evidence of local crystallization at room temperature (RT) was verified. Meanwhile, the distance-dependent crystallization behavior was investigated in terms of gradually increased quantity of diffraction spots and precipitated nanocrystalline adjacent to indentation edge. Furthermore, high resolution transmission electron microscopy (HRTEM) images and SAED patterns at identical indentation microregion of tensile-fractured BMG specimen did not exhibit obvious nanocrystalline and diffraction spots, which indicated that the cyclic stress rather than static stress induced surface crystallization adjacent to indentation edge at RT. [ABSTRACT FROM AUTHOR]

The epitaxial growth of silver on copper benefits carriers' transport across interfaces and is thus important for opto-electronic applications and catalysis. Cu-Ag bimetallic nanoparticles have long been fabricated using chemical methods. The epitaxial growth of silver on copper has been rarely reported. In this study, we demonstrate the fabrication of Cu-Ag bimetallic nanoparticle with a configuration of silver epitaxial growth on copper via thermal evaporation deposition in vacuum, in which not only the oxidation of copper is reduced but also contamination is avoided. Meanwhile, a core-shell-like bimetallic nanoparticle with a copper core and a silver shell is also fabricated. The configurations of the two kinds of Cu-Ag bimetallic nanoparticles were explored by analyzing the changes of the X-ray photoelectron spectra, high resolution transmission electron microscopy images, diffraction rings, and glancing angle X-ray diffraction patterns with the increasing amount of silver and copper. A model of lattice matching between silver on copper was also established for the epitaxial Cu-Ag bimetallic nanoparticle. The layered epitaxial bimetallic nanoparticle show strong anti-oxidation effect and obvious localized surface plasmon resonance damping of Ag nanoparticles, suitable for applications requiring anti-oxidation and low absorbance. • Two kinds of Cu-Ag bimetallic nanoparticles fabricated by thermal evaporation. • The epitaxial growth of AgNPs on CuNPs was demonstrated. • Copper oxides were reduced once combined with Ag atoms. • The bimetallic nanoparticles show strong anti-oxidation. • The sample 1.0 nmCuNPs–1.0 nmAgNPs shows LSPR damping effect. [ABSTRACT FROM AUTHOR]

The lattice disorder and elemental distribution in He-implanted GaN epilayer at a fluence of 4 × 1016 He+/cm2 at 450 °C have been investigated by a combination of conventional, high resolution transmission electron microscopy and electron energy loss spectroscopy. High resolution transmission electron microscopy shows interstitial-type dislocation loops attached to He bubbles. The nature of dislocation loops and stacking faults are carefully investigated by high resolution transmission electron microscopy. Electron energy loss spectroscopy shows the deficit of N atoms and enriched Ga nanocrystals formed in the damage region, which is comparable with the previous reports. In addition, the chemical environment of nitrogen upon He+ implantation is first investigated in the present experimental results. The research results will be used for understanding ion irradiation-induced damage in GaN. • Lattice disorder in He+ ion-implanted GaN at 450 °C was investigated. • > The nature of dislocation loops and stacking faults are investigated by transmission electron microscopy. • > Electron energy loss spectroscopy shows the deficit of N atoms and Ga nanocrystals formed in the damage region. [ABSTRACT FROM AUTHOR]

Rational construction of crystalline/amorphous tungsten trioxide core/shell nanowire arrays have been obtained by combing solvothermal and magnetron sputtering techniques. High resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) characterization results reveal that the core/shell nanowires are composed of single crystal hexagonal tungsten trioxide nanocores sheathed with amorphous tungsten trioxide nanoshells. By the well-controlled sputtering technique, the thickness of the amorphous WO 3 nanoshell can be precisely modulated which determines evidently electrochromic properties of the core/shell nanostructure. The optimized core/shell nanowires display exceptional electrochromic properties of high optical contrast (84.5% at 633 nm and 80.0% at 1500 nm), fast switching speeds (1.2 s for bleaching and 3.6 s for coloring)，high coloration efficiency (83.6 cm2/C at 633 nm) and exceptional cycle stability (91.9% after 3000 cycles). The enhanced performance can be attributed to the complementary advantages of the crystalline nanocores and the well-defined amorphous nanoshells as well as their interface interaction. The strategy of synthesizing crystalline/amorphous core-shell nanoarrays proposes a reliable solution to produce high performance electrochromic materials and devices such as energy saving smart window, outdoor static displays and other energy-efficient applications. One-dimensional crystalline/amorphous WO 3 core/shell nanowire arrays are obtained which displays exceptional electrochromic properties of high optical contrast, fast switching speed and excellent cycle stability. The enhanced electrochromic performance can be attributed to complementary advantages of the crystalline/amorphous components as well as their interfacial synergistic effect, in which the crystalline nanocores may offer have strong inter-atomic bonding and superior chemical stability, while the well-defined amorphous nanoshells provide large number of open polygonal voids for ion transport. Unlabelled Image • WO 3 core/shell nanowires array are vertically prepared on FTO substrate. • The nanowires consist of crystalline nanocores wrapped by amorphous nanoshells. • The thickness of the amorphous WO 3 nanoshells can be precisely modulated. • Nanowires show enhanced electrochromic properties due to synergistic effect. [ABSTRACT FROM AUTHOR]

To increase the adhesion and reduce the coefficient of friction (COF), two key factors to determine the performance of a coating, MeN (Me = Ti, Cr, Zr, Mo, Nb x Al 1 − x) coating have been incorporated in TiSiN coating formed nano-amorphous composite multilayered coatings. MeN/TiSiN (Me = Ti, Cr, Zr, Mo, Nb x Al 1 − x) coatings were deposited by cathodic arc ion plating using alloy targets with fixed parameters. The microstructure was investigated by X-ray diffraction (XRD) and high resolution Transmission Electron Microscopy (HRTEM) and revealed nano-composite multilayer structure with clear interface. The cross-sectional morphologies and surface roughness have been revealed by scanning electron microscopy and surface profilometer. MoN/TiSiN and CrN/TiSiN coating possessed the smoothest and most coarse surface which resulted from particles and pores. The COF and adhesion were evaluated by ball-on-disk tester and scratch test, respectively. Multilayered TiSiN coatings revealed excellent adhesion (with critic load higher than 70 N) and relative lower COF (ranged from 0.3 to 0.58). CrN/TiSiN revealed the highest hardness of 32.5 GPa and the largest critic load of 114.3 N while MoN/TiSiN revealed the lowest COF of 0.32. The critic load of CrN/TiSiN coating identified from the acoustic signal, friction variation and morphologies is 114.3 N which is the largest value among these five multilayered TiSiN coatings. The excellent adhesion should be attributed to the high energy metallic ions produced by arc ion technology and the alternating stress field formed by multilayer structure. Unlabelled Image • MeN/TiSiN (Me = Ti, Cr, Zr, Mo, Nb x Al 1 − x) multilayer coatings were synthesized. • Nano-composite multilayered structure was observed in all coatings. • CrN/TiSiN coating revealed the largest hardness and best adhesion. • MoN/TiSiN presented lowest COF due to its self-lubrication. [ABSTRACT FROM AUTHOR]