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This study investigates the effect of laser volume energy density (VED) on the properties of AISI 420 stainless steel and TiN/AISI 420 composite manufactured by selective laser melting (SLM). The composite contained 1 wt.% TiN and the average diameters of AISI 420 and TiN powders were 45 µm and 1 µm, respectively. The powder for SLMing the TiN/AISI 420 composite was prepared using a novel two-stage mixing scheme. The morphology, mechanical, and corrosion properties of the specimens were analyzed, and their correlations with microstructures were investigated. The results showed that the surface roughness of both SLM samples decreases with increasing VED, while relative densities greater than 99% were achieved at VEDs higher than 160 J/mm3. The SLM AISI 420 specimen fabricated at a VED of 205 J/mm3 exhibited the highest density of 7.7 g/cm3, tensile strength (UTS) of 1270 MPa, and elongation of 3.86%. The SLM TiN/AISI 420 specimen at a VED of 285 J/mm3 had a density of 7.67 g/cm3, UTS of 1482 MPa, and elongation of 2.72%. The microstructure of the SLM TiN/AISI 420 composite displayed a ring-like micro-grain structure consisting of retained austenite on the grain boundary and martensite in the grain. The TiN particles strengthened the mechanical properties of the composite by accumulating along the grain boundary. The mean hardnesses of the SLM AISI 420 and TiN/AISI 420 specimens were 635 and 735 HV, respectively, which exceeded previously reported results. The SLM TiN/AISI 420 composite exhibited excellent corrosion resistance in both 3.5 wt.% NaCl and 6 wt.% FeCl3 solutions, with a resulting corrosion rate as low as 11 µm/year.

Amorphous metals have wide applications, including those in various transducer and sensor devices, because of their extraordinary physical and chemical characteristics, excellent mechanical propert...

This work studied on the development of novel cathodes for proton-conductive solid oxide fuel cells (p-SOFCs) made of powders La3Ni2O7+δ(LNO2) mixed with Ba0.5Sr0.5Co0.8Fe0.2O3-δ(BSCF). The cathodes were constructed by a skeleton of LNO2 whose surface coated by BSCF in the ratio (in wt. %) of LNO2/BSCF varying in 15/85, 30/70, 50/50, 75/25 (denote as LN15, LN30, LN50, and LN75, respectively). The skeleton was responsible for carrier conduction and air transportation; the BSCF coating was responsible for catalytic oxygen reduction reaction (ORR). Nascent powders directly collected from combustion were subject to examination by scanning electron microscope (SEM) and X-ray diffractometer (XRD) and further calcination. Well crystalized with highly pure powders obtained post their calcination at 900 °C. Performing the button cells by means of I-V testing at 600, 700 and 800°C, the data of maximum power density () depicted the order LN75 < BSCF < LN15 < LN30< LN50 regardless of temperatures. Among all the specimens, LN50 could be the best cathode candidate for P-SOFCs.

In this study, the various Sr(Ce0.6Zr0.4)0.9Y0.1O3-δ/YBaCo2O5+δ (SCZY/YBCO) composite ceramic membranes were prepared by sintering at different temperatures and used as proton membranes for hydrogen permeation. SCZY and YBCO powders were prepared by the citrate-ethylenediaminetetraacetic acid sol-gel process and solid-state reaction method, respectively. The chemical reaction, structure, morphology, thermal expansion, and electrical conductivity of SCZY/YBCO were investigated through X-ray powder diffraction (XRD), scanning electron microscopy (SEM), thermal mechanical analyzer (TMA) and direct current four-probe method. The relative sintered density of SCZY/YBCO membrane sintered at 1250 °C was as high as 99.5%. The conductivity of the SCZY/YBCO increased with the sintering temperature. The SCZY/YBCO sample sintered at 1250 °C exhibited the highest conductivity of 13.44 S/cm at 800 °C. The H2 permeability of the SCZY/YBCO membrane was 3.83 mL min−1 cm−2, much higher than that of SCZY at 800 °C (1.37 mL min−1 cm−2).

A thin and fully dense BaCe0.6Zr0.2Y0.2O3-δ (BCZY) electrolyte for the use of anode-supported protonic fuel cells has been successfully prepared by spin coating using NiO sintering aid. The effects of NiO addition on the electrolyte microstructures and fuel cell performances are also investigated. An appropriate NiO addition has a significant positive contribution to the densification and grain growth of thin BCZY electrolytes. However, too much NiO addition gives rise to NiO aggregation in BCZY electrolyte and deteriorates the cell performance. The enhanced sintering mechanism can be mainly attributed to the oxygen vacancies generated from the NiO decomposition and bulk diffusion of Ni into BCZY perovskites. The fuel cell with a BCZY-3%NiO electrolyte exhibits the highest maximum power density of ~106.6 mW/cm2 at 800 °C among all fuel cells in this study. The electrochemical impedance characteristics of thin BCZY electrolyte fuel cells are further discussed under open circuit conditions.

To determine the optimal combination of NiO and Ba 0.8 Sr 0.2 Ce 0.6 Zr 0.2 Y 0.2 O 3-δ (BSCZY) for fabricating anode materials, Ni-BSCZY samples were prepared using the solid state reaction process. The porous structure of anode substrates not only provides mechanical strength to the fuel cells to enable fuel gases to flow to the electrolyte membrane but also creates an excess surface area on which to form a larger triple-phase boundary when NiO is added to the anode sample. The effect of NiO content on the microstructures, surface area, and electric conductivity of these Ni-BSCZY (NiO55-BSCZY, NiO60-BSCZY, and NiO65-BSCZY) anode materials were systematically investigated using X-ray diffraction, scanning electron microscopy, an analytic technique based on the Brunauer–Emmett–Teller surface area theory, and four-probe conductivity analysis. In addition, three anode-supported cells containing identical electrolytes but various combinations of NiO and BSCZY anode materials were fabricated and used for performance and electrochemical impedance measurement. The results revealed that the reactive surface area of the anode in contact with the electrolyte plays a crucial role in total cell performance. The cell containing the anode material (NiO60-BSCZY) with the highest surface area of 6.91 m 2 g −1 and the lowest total resistance of 2.19 Ω cm 2 exhibited the highest power density of 169.2 mW cm −2 at 800 °C.

In this study, an electrochemical deposition was conducted to prepare Al:ZnO. Products in three distinct phases were obtained depending on the [Al3+] added in the bath of 2.0 mM zinc nitrate. For convenient description, [Al3+] (total range 0–1000 μM) was termed as dilute (i.e., [Al3+] 250 μM). Field-emission scanning electron microscopy revealed that a compact phase of nanorods was deposited in the dilute [Al3+], a mixed phase consisting of nanorods and nanosheets was deposited in the medium [Al3+], and a loose phase of cloudy floc was produced in the concentrated [Al3+]. By analyzing the reaction products with grazing incidence X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy, we distinguished the crystal film of aluminum-doped zinc oxide nanorods from the amorphous hydroxides. Mott-Schottky measurements revealed that the specimen of nanorods doped with 2.84 at.% Al displays the highest carrier concentration (3.83 × 1018 cm−3) and demonstrates the highest electric conductivity among the specimens in a compact phase of nanorods. Photovoltaic tests showed that these films have fill factor and solar cell power conversion efficiency of 70.6 and 2.15%, respectively. By means of cathodic polarization and analysis of basic chemistry in aqueous solution, we propose a comprehensive mechanism to illustrate the type of products depending on [Al3+].

Cu-Zn alloy micropillars were fabricated by a potentiostatic localized electrochemical deposition (LECD) process. This process was carried out via micro-anode-guided electroplating in a pyrophosphate bath at a constant negative potential in the range −1.85 to −2.05 V. Different products were produced, depending on the initial inter-electrode gap employed. Thus, at an initial gap of 40 μm, the process afforded micropillars with a single α-brass crystal phase and at.% Zn contents in the range 17.20–32.01%. A reduction in the initial gap to 30 μm resulted in varied micropillar crystal phases (α, β, and β + β') with at.% Zn contents in the range 37.12–68.94. The simulation commercial software COMSOL 5.2 was employed to correlate the asymmetric distribution of the electric field to the experimental parameters and pillar characteristics. The resultant data was then used to delineate the dependence of the field strength on the crystal phase, composition, growth rate, and micropillar diameters. Finally, a potentiodynamic cathodic polarization study was employed to elucidate the mechanism for the fabrication of the Cu-Zn alloy micropillars via potentiostatic LECD.

Microanode-guided electroplating (MAGE) was performed to prepare cobalt-iron-nickel alloying micropillars. The electrolyte was prepared by fixing [Fe2+] at 0.040 M and varying [Co2+] in 0.040–0.100 M and [Ni2+] in 0.30–0.60 M. The effect of bath composition on the compositional, mechanical, and magnetic properties of the alloying micropillars was investigated. Resulting from FE-SEM and EDS, all the micropillars demonstrated a smooth morphology but in different compositions depending on the bath composition. Through XRD analysis, the micropillars were characterized in nanocrystals of Co-Ni and Co7Fe3. After nano-indentation testing, the reduced Young’s modulus of the pillars was estimated at 103.1–185 GPa and the hardness at 5.70–6.38 GPa. Investigation of all the specimens with VSM, Co61Fe27Ni12 and Co63Fe25Ni12 displayed the notable saturation magnetization (Ms = 180 and 175 emu/g) and the lowest coercive magnetic field (Hc = 2.1 and 1.4 Oe) among them. The mechanism of anomalous Co-Fe-Ni electrodeposition is proposed.

This study first reports the K doping optimization in proton-conducting Ba 1-x K x Ce 0.6 Zr 0.2 Y 0.2 O 3-δ ( x = 0.025–0.2) oxides synthesized by using a combination of citrate-EDTA complexing sol-gel process and composition-exchange method. Among all samples, the ceramic pellet with a K doping content of 10% exhibits excellent sinterability, highest relative density, highest protonic conduction, and also excellent chemical stability against CO 2 . Moreover, the Pt/electrolyte/Pt single cell with such a Ba 0.9 K 0.1 Ce 0.6 Zr 0.2 Y 0.2 O 3-δ electrolyte shows a significantly higher maximum powder density in the hydrogen-air fuel cell experiment, which can be attributed to its denser microstructures and higher protonic conductivity caused by introducing highly basic K cations. Based on these experimental results, we discuss the improvement mechanism in terms of calcined K-doped particle characteristics. This work demonstrates that the Ba 1-x K x Ce 0.6 Zr 0.2 Y 0.2 O 3-δ oxide synthesized by the sol-gel combined with composition-exchange method with an optimal K doping would be a promising electrolyte for proton-conducting fuel cell applications.

Cu–Zn alloy micropillars were fabricated using microanode-guided electroplating (MAGE) at a constant voltage of 4.6 V under an initial inter-electrode gap of 30 µm in pyrophosphate baths. Energy-dispersive spectroscopy and X-ray diffractometry analysis revealed that the micropillar alloys exhibit an increase in the Zn content from 8.05 at.% (in α phase) to 54.60 at.% (in β, and β' phases) with an increase in the ratio of [Zn2+]/[Cu2+] in the bath from 8/1 to 128/1. Transmission electron microscopy revealed that the Cu–Zn alloy micropillars were composed of nano-grains with different sizes depending on the bath employed. Nano-indentation test indicated that the micropillar containing 40.51 at.% Zn (in presence of β-phase) exhibits the maximum hardness (at 5.30 GPa) and highest Young's modulus (at 113.64 GPa). Simulation of the electric field using the commercial software COMSOL 5.2 revealed that the highest field strength centralized at the cylindrical top displayed only a slight increase (from 152.2 to 152.5 kV/m) with an increase in the ratio of [Zn2+]/ [Cu2+] in the bath. Potentiodynamic cathodic polarization is useful for understanding the mechanism of microanode-guided electroplating. Electrochemical impedance spectroscopy performed at characteristic potentials confirms the mechanism extremely well.

In this study, Ga-doped ZnO thin films were prepared using sol–gel technique via spin-coating method. The effect of Ga-doping dopant (0, 1, 2 and 3 at.%) on microstructural, optical, electrical and photoelectrochemical (PEC) characteristics have been investigated. The spin-coating was repeated six times, and as-obtained thin films were then annealed at 500 °C for 1 h in vacuum. After annealing, all samples revealed single phase of hexagonal ZnO polycrystalline structure with a main peak of (002) in X-ray diffraction (XRD) pattern. Raman spectra show that the vibration strength of E2 is highly decreased by Ga doping. Thicknesses of all samples were ~300 nm measured via scanning electron microscopy (SEM) cross-section images and alpha-step. The optical band gap and resistivity of samples were in the range of 3.24 to 3.28 eV and 102 to 9 Ohm cm, respectively. Resulting from PEC response, the 2 at.% Ga-doped ZnO thin film has a better PEC performance with photocurrent density of ~0.14 mA/cm2 at 0.5 V versus saturated calomel electrode (SCE) under illumination with the intensity of 100 mW/cm2. This value was about seven times higher than the un-doped film (reference sample). Observed higher photocurrent density was likely because of a suitable Ga-doping concentration causing a lower resistivity. Copyright © 2016 John Wiley & Sons, Ltd.

Sodium titanium phosphate (NaTi2(PO4)3, NTP) with a sodium superionic conductor structure is considered as an efficient anode material for aqueous sodium-ion batteries because of its moderate potential range and high structural stability. In this study, a series of NTP nanoparticles (NPs) were synthesized using a facile and cost-effective hydrothermal method without further calcination to explore the influence of reaction time on their crystalline structures and morphologies. The NTP NPs hydrothermally synthesized for 5 h were subsequently subjected to a carbon-coating procedure, and the resulting carbon-coated NTP NPs exhibited remarkable reversible capacities, rate capabilities, and cycling performances. These features were attributable to the nanotailoring of the NTP NPs, which reduced both the ionic and electronic transporting paths, and continuous carbon layers coated on the NTP surfaces to promote their electronic conductivities.

Electrochemical corrosion of as-cast and annealed zirconium-based bulk metallic glass (BMG) Zr48Cu36Al8Ag8 in 0.1 M NaCl solution was investigated in this work. The as-cast specimen, in complete amorphous form, contained null percent of crystal phase (denoted as 0C); however, the annealed ones contained 11, 25, 50, 75 and 100 % crystal phase (denoted as 11C, 25C, 50C, 75C and 100C, respectively) determined by the annealing duration of 0C specimen at 471 °C. Through monitoring of open circuit potential (OCP), measurements of direct-current polarization resistance (PR), Tafel plot (TP), cyclic anodic potentiodynamic polarization (CAPD), and electrochemical impedance spectroscopy (EIS), we found that the corrosion behavior of the Zr48Cu36Al8Ag8 was detremined by the the crystal phase present in the specemns dominated by the annealing durations. The corrosion resistance decreased in the order: 25C > 11C > 0C > 50C > 75C > 100C. This result revealed that the corrosion resistance inclined to be better and reached a mxmium with increasing the percentgae of the crystal phase from 0 to 25%; however, it decreased with further increasing the crystal phase over 25%. A corrosion mechanism is proposed to rationalize the sequence of corrosion resistance. According to the mechanism, the remained free volume and residual strain energy are responsible for the specimens containing crystal phase less than 25% (i.e., 0C, 11C and 25C); whereas crystal defects such as grain boundaries governed the corrosion of those containing crystal phase more than 25 % (i.e., 50C, 75C and 100C).

Electrochemical deposition of Al-doped ZnO (AZO) on the ITO glass was investigated in baths containing various concentrations of aluminum nitrate. The electrochemical and chemical reactions can be deduced by means of investigating cathodic polarization curves and time/electroplating-current curves for further characterizing structures of ZnO and AZO, and establishing growth mechanism. High-quality AZO nanorods, depositing on ITO substrate that coated with ZnO seed-layer, were utilized the electrochemical method at-1.0 V (against a reference electrode of Ag/AgCl in 3.0M KCl) in the bath of 90 °C. After annealing at 350 °C, ZnO and AZO nanorods were analyzed by field-emission scanning electron microscope (FESEM) to explore the morphology of nanostructure. The SEM image displayed that the lower Al3+ concentrations (20 ~ 60 μM) in the bath, the average diameter of nanorods decreased; while the Al3+ concentrations excessed over 60 μM, the morphology of the AZO nanorods turned into partial-area nanosheets instead of the nanorods spread. The crystal structure of the AZO nanorods were identified by using grazing-incident X-ray diffraction (GIXRD). The patterns of the Al3+ ions in the range of 20 ~ 60 μM in the bath showed that the preferred orientations were along with the [002] direction which confirmed the result of AZO nanorods well aligned in c-axis orientation, and the characterized peak (002) slightly shifted to the right suggested that Al atoms had doped into the ZnO lattice. We also adopted the X-ray photoelectron spectroscopy to characterize the elemental and chemical compositions of the AZO nanorods. XPS spectrums confirmed that the Al atoms successfully doped. Finally, for identifying the optimal boundary condition of Al content in ZnO, the nanorods with various Al concentrations were utilized via dye-sensitized solar cells (DSSC) experiment with the standard solar Simulators (AM1.5G) and J-V Measurement. We found that the AZO nanorods as the photoanode contained 2.84 at.% Al (60 μM aluminum nitrate in the bath) which performed the highest fill-factor (0.53) and the maximum efficiency (0.41%).

In this study, effect of anodization temperature on the photoelectrochemical (PEC) performance of nanostructured hematite films prepared by anodizing the sputtered iron films on the fluorine-doped SnO 2 glass substrate was investigated. It was noted that increasing the anodization temperature would induce the hematite nanostructure developing from film-like to nanorod morphology. Importantly, this morphology transformation is noted to accompany with the enhanced PEC performance up to 0.59 mA/cm 2 (nanorod structured anodized at 60 °C). Our results clearly demonstrated that the potential of post-treatment using anodization to further enhance the PEC performance of hematite films.

Zinc oxide (ZnO) nanostructures were fabricated on the polished zinc foil by anodic deposition in an alkaline solution containing 1.0 M NaOH and 0.25 M Zn(NO 3 ) 2 . Potentiostatic anodization was conducted at two potentials (−0.7 V in the passive region and −1.0 V in the active region vs. SCE) which are higher than the open circuit potential (−1.03 V vs. SCE) and as-obtained ZnO nanostrcutures were investigated focusing on their structural, optical, electrical and photoelectrochemical (PEC) characteristics. All samples were confirmed ZnO by X-ray photoelectron spectroscopy and Raman spectra. Observations in the SEM images clearly showed that ZnO nanostructures prepared at −0.7 V vs. SCE were composed of nanowires at while those obtained at −1.0 V vs. SCE possessed nanosheets morphology. Result from transmission electron microscope and X-ray diffraction patterns suggested that the ZnO nanowires belonged to single crystalline with a preferred orientation of (0 0 2) whereas the ZnO nanosheets were polycrystalline. Following PEC experiments indicated that ZnO nanowires had higher photocurrent density of 0.32 mA/cm 2 at 0.5 V vs. SCE under 100 mW/cm 2 illumination. This value was about 1.9 times higher than that of ZnO nanosheets. Observed higher photocurrent was likely due to the single crystalline, preferred (0 0 2) orientation, higher carrier concentration and lower charge transfer resistance.

the purpose of this research was to develop a new micro-anode-guided electroplating (MAGE) system equipped by an image-guided positioning controller, to fabricate two-dimensional microstructures. From real-time image, the relative positions of the micro-anode and the microstructures tip can be located and maintained. When the relative position is adjusted, the deposition direction of the microstructures can be controllable and microstructures with different geometries can be fabricated. Moreover, the results of experiment can be explained by the distribution of electro field strength simulated by Comsol Multiphysics 4.2.

Thin films of α-Fe2O3 doped with carbon have been fabricated on F-doped SnO2 glass substrate by magnetron sputtering process via DC power on the pure Fe target (99.99%) combined with RF power on the pure graphite target (99.99%). The influences of RF power (0, 40, 80 and 120 W) on optical, structural and photoelectrochemical (PEC) characteristics have been investigated. The as-obtained samples after annealing in Ar ambient were analyzed by scanning electron microscopy, X-ray diffraction (XRD), Raman spectra, UV–visible spectra and electrochemical analysis. After annealing, all samples revealed only hematite characteristics in XRD pattern and Raman spectra. Thickness of annealed thin films was ∼350 nm measured via SEM cross-section image. The optical band gap and carrier concentration of samples were in the range of 2.13–2.16 eV and 6.28 × 1017 to 3.11 × 1018 cm−3, respectively. Based upon our observations, the 4.56 at.% carbon-doped α-Fe2O3 thin film deposited via 80 W RF power has a better PEC response with photocurrent density of ∼1.18 mA/cm2 at 0.6 V vs. SCE. This value was about three times higher than the un-doped film (0 W of RF power, reference sample). Observed higher photocurrent density was likely due to a suitable carbon-doping concentration causing a higher carrier concentration.

The carbon steel (CS) was anodized to coat with vertical arrays of nanotubes in a mixture of aqueous ammonium fluoride solution and ethylene glycol. As-anodized specimens were annealed at 450 °C for 4 h in Ar ambient. The fabricated iron oxide nanotube arrays (NTA) depicted a layer of nanotubes over 500 nm in length, about 80 nm in diameter and about 30 nm in wall thickness shown from scanning electron microscope images. X-ray diffraction pattern indicated that iron oxide NTA contained α-Fe 2 O 3 as the main phase and Fe 3 O 4 as the secondary phase. UV–visible absorption spectra revealed iron oxide NTA significantly absorbed light up to 700 nm. Potentiodynamic polarization curves of iron oxide NTA and CS were investigated in 0.5 wt.% NaCl solutions in the dark and under illumination supplied by solar simulator. We found that iron oxide NTA shows tremendous photoeffect under alternative illumination and dark. It was seen that potential of iron oxide NTA was more negative under illumination than in the dark and the corrosion rate of CS covered with NTA was obviously less than undecorated CS. In addition, the model of photoelectrochemical anticorrosion of iron oxide NTA was explored.

Thin films of p-type β-CuSCN were deposited on indium–tin oxide glass substrates via electrochemical process. Various annealing temperatures (200, 300 and 400 °C) were taken into consideration. The influence of annealing temperature on structural, optical, electrical and photoelectrochemical characteristics of β-CuSCN thin films were investigated. Results from X-ray diffraction indicated as-obtained β-CuSCN thin film was in a hexagonal close pack crystal structure. We found that the crystallographic orientation changed and the optical energy band gap slightly increased with increasing annealing temperatures. These properties made CuSCN films annealed at 400 °C a better photoelectrochemical performance with photocurrent density of about −0.39 mA/cm2 at −0.5 V vs. SCE. This value is about 5 times higher than the as-deposited CuSCN film. Observed higher photocurrent density is likely due to the intrinsic of a higher charge carrier concentration, and a lower resistance within CuSCN crystal and at CuSCN/electrolyte interface.

In this study, proton-conducting Sr(Ce0.6Zr0.4)0.85Y0.15O3−δ perovskite is synthesized using the citrate-ethylenediaminetetraacetic acid (EDTA) complexing method. The crystal structure, sintering behavior, coefficient of thermal expansion (CTE), electrical conductivity, electrochemical performance and hydrogen permeation of the Sr(Ce0.6Zr0.4)0.85Y0.15O3−δ is determined for various atmospheres and partial pressures of water. Sr(Ce0.6Zr0.4)0.85Y0.15O3−δ is extremely dense after sintering at 1450 °C for 6 h. The structure of the Sr(Ce0.6Zr0.4)0.85Y0.15O3−δ does not change after heat treatment in a hydrogen atmosphere at a partial pressure of water of 4.93 × 10−2 atm. The CTE of the Sr(Ce0.6Zr0.4)0.85Y0.15O3−δ at temperature of 100–900 °C is 11.4 × 10−6 K−1. The electrical conductivity of the sample is 0.012 S cm−1 at 900 °C. The hydrogen permeation flux increases from 0.1 to 0.184 mmol min−1 cm−2 as the temperature increases from 500 °C to 800 °C.

SrCe1−xZrxO3−δ (0.0 ≦ x ≦ 0.5) proton-conducting oxides had been successfully prepared using a solid state reaction method. In this study, the relationships between the Zr contents and microstructures, shrinkages, and sintering of these SrCe1−xZrxO3−δ (0.0 ≦ x ≦ 0.5) were systemically studied by using X-ray Diffraction, Scanning Electron Microscopy, and Thermal dilatometer analysis (TDA). The XRD results showed that no second phase could be found from the 1500 °C sintered SrCe1−xZrxO3−δ. The SEMs shows that the porosities of sintered SrCe1−xZrxO3−δ increased with increasing the Zr contents. The largest porosity about 27.53% could be obtained at the SrCe0.6Zr0.4O3−δ ceramics sintered at 1500 °C for 2 h in the SrCe1−xZrxO3−δ ceramics. According to the sintering behaviour and properties characterizations, a flat HTM with porous supporting layers of SrCe0.6Zr0.4O3−δ and SrZrO3 was fabricated by constrained sintering. Therefore, the SrCe0.6Zr0.4O3−δ ceramic is suggested to be a potential support layer material for HTM applications.

International audience; Transparent conductive zinc oxide co-doped with tin and aluminum (TAZO) thin films were prepared via sol–gel dip-coating process. Non-toxic ethanol was used in this study instead of 2-methoxyethanol used in conventional work. Dip-coating was repeated several times to obtain relatively thick films consisting of six layers. The films were then annealed at 500 °C for 1 h in air or in vacuum and not subsequently as employed in other studies. The X-ray diffraction patterns indicated that all the samples revealed a single phase of hexagonal ZnO polycrystalline structure with a main peak of (002). The optical band gap and resistivity of the TAZO films were in the ranges of 3.28 to 3.32 eV and 0.52 to 575.25 Ω cm, respectively. The 1.0 at.% Sn, 1.0 at.% Al co-doped ZnO thin film annealed in vacuum was found to have a better photoelectrochemical performance with photocurrent density of about 0.28 mA/cm2 at a bias of 0.5 V vs. SCE under a 300 W Xe lamp illumination with the intensity of 100 mW/cm2. Compared to the same dopant concentration but annealed in air (~ 0.05 mA/cm2 bias 0.5 V vs. SCE), the photocurrent density of the film annealed in vacuum was 5 times higher than the film annealed in air. Through electrochemical measurements, we found that the dopant concentration of Sn plays an important role in TAZO that affected photocurrent density, stability of water splitting and anti-corrosion.

Thin films of polycrystalline AgInS 2 were deposited on indium–tin oxide glass substrates by chemical bath deposition process. Various dipping cycles (1, 2, 3, 4 and 5) were taken into consideration. The influence of dipping cycle on structural, optical, electrical and photoelectrochemical characteristics of the AgInS 2 thin films were investigated. The X-ray diffraction patterns indicated that all the samples revealed single phase of orthorhombic AgInS 2 with polycrystalline structure. The thickness of samples in a range of 0.82–2.67 μm analyzed by α-step instrument. The optical band gap of all AgInS 2 films were 1.94 eV calculated by transmittance spectra, respectively. All the samples revealed n -type semiconductor behaviors by Hall measurement. The carrier concentrations, mobility and resistivity of the AgInS 2 films at room temperature were in the range of 10 12 –10 15 cm −3 , 1.9–15 cm 2 V −1 s −1 and 10 3 –10 5 Ω cm, respectively. We found that the dipping 3 cycles AgInS 2 film had a better photoelectrochemical performance with photocurrent density of 3.50 mA/cm 2 bias 0.5 V vs. SCE reference electrode under a 300 W Xe lamp illumination with the intensity of 100 mW/cm 2 . This value was about 3 times higher than the dipping 5 cycles AgInS 2 film. Observed higher photocurrent density was likely due to a suitable thickness, higher carrier mobility and lower charge transfer resistance.

Porous hematite (α-Fe 2 O 3 ) hollow sphere structures have been fabricated on fluorine-doped SnO 2 (FTO) glass substrate by DC magnetron sputtering process via polystyrene spheres (PS) latex as templates. The influences of deposition time and PS template on optical, structural and photoelectrochemical characteristics have been investigated. The as-obtained samples after annealing in ambient atmosphere were analyzed by scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Raman spectra, UV–visible spectra and electrochemical analysis. After annealing, all samples revealed only hematite characteristics in the Raman spectra. TEM images confirmed the porous hollow sphere structures which deposited for 20 and 30 min via PS templates. Based upon our observations, the porous α-Fe 2 O 3 hollow spheres deposited for 30 min had a better photoelectrochemical performance with photocurrent density of about 1.4 mA/cm 2 at 0.6 V vs. SCE. This value was about 3 times higher than the no modified film (reference sample). Observed higher photocurrent density was likely due to a hollow sphere structure and a suitable thickness causing a higher charge carrier concentration and a lower charge transfer resistance.

A novel microsensor, consisting of crossed Cu micropillars coated with ZnO nanorods, was fabricated by electrochemical methods for detecting gas in a small space. The Cu micropillars (80 μm diameter, 10 mm long) were prepared by microanode-guided electroplating (MAGE) on the periphery of a square copper pad (dimensions 5.0 mm × 5.0 mm × 1.0 mm). The micropillars were electrochemically coated with a 500 nm thick layer of ZnO nanorods deposited from a bath containing 2.0 mM zinc chloride and H2O2 varying in 5, 10, 15, and 20 mM. Two ZnO-coated pillars were crossed to form a microsensor by approaching the Cu pads below, which was adhered to an alumina substrate with silver paste and connected to conducting wires for measurement. The morphology of the coating of ZnO nanorods, which was found to be determined by the concentration of H2O2 in the bath, influenced the gas sensing. The morphology of the coating was characterized by scanning electron microscopy; the structural analysis was carried out by X-ray diffraction and high-resolution transmission electron microscopy (HRTEM); the surface analysis was carried out by X-ray photoelectron spectroscopy; and the defects were determined with photoluminescence (PL) spectra. We thus investigated the effect of the morphology of the coating on the sensing properties by introducing a stream of gases varying in CO/air ratios to understand the sensing mechanism of the microsensor.

In this study, we attempted to quantitatively interpret the effect of electrodeposition temperature on Cu2O film's microstructure, optical and photoelectrochemical properties. Three deposit temperatures (35, 50 and 65 °C) were taken into consideration. Based upon our observations, a general trend was concluded. That is, Cu2O films deposited at lower temperature (35 °C) always possessed a high degree of preferential orientation, smaller pyramidal-like crystal size, high photolumminance and a higher carrier concentration. These properties made Cu2O films deposited at 35 °C a better photoelectrochemical performance with photocurrent density of −0.22 mA/cm2 bias −0.4 V vs. SCE. This value is about 35% higher than those Cu2O films deposited at higher temperatures. Observed higher photocurrent density is likely due to the intrinsic of a higher charge carrier concentration, and a lower resistance within Cu2O crystal and at Cu2O/electrolyte interface.

Ba 0.6 Sr 0.4 Ce 0.8− x Zr x Y 0.2 O 3− δ ( x = 0–0.8) proton-conducting oxides are prepared using a sol–gel complexing process. The effects of the Ce/Zr ratio on various material properties are systematically investigated. The sintered samples show a perovskite crystal structure without impurity phases and have a rather compact interior, making them suitable for use as a fuel cell electrolyte. Increasing the Zr content in the oxides causes lattice constriction and suppresses grain growth during sintering at 1600 °C. The ionic conductivity of the oxides increases with increasing Ce/Zr ratio. At 800 °C, Ba 0.6 Sr 0.4 Ce 0.8 Y 0.2 O 3− δ has a conductivity of as high as 0.14 S/cm. However, X-ray diffraction and Raman spectroscopy evaluations show that this oxide cannot withstand a CO 2 atmosphere. A suitable substitution of Ce with Zr in the structure significantly improves the chemical stability of the oxide without significantly degrading conductivity.

Ba1−xSrxCe0.6Zr0.2Y0.2O3−δ (0.0 ≤ x ≤ 1.0) proton-conducting oxides have been prepared using a citrate-EDTA complexing sol–gel method. In this study, the relationship between the Sr doping content and microstructure, chemical stability against CO2, and conductivity of the sintered Ba1−xSrxCe0.6Zr0.2Y0.2O3−δ pallets are systematically investigated using XRD, SEM, micro-Raman spectroscopy, and dc two-probe measurements. All sintered Ba1−xSrxCe0.6Zr0.2Y0.2O3−δ oxides exhibit excellent chemical stability after being exposed to the CO2 ambient at 600 °C for a long duration; nevertheless, their microstructures and conductivities are very sensitive to the Sr doping amount. The Sr incorporation is found to apparently suppress the formation of CeO2-like second phase, and enhance the grain growth in sintered oxides. Among all sintered samples, the Ba0.8Sr0.2Ce0.6Zr0.2Y0.2O3−δ pallet has the highest conductivity, 0.009 S/cm at 800 °C. This result can be attributed to the competition between the elimination of CeO2- or (Zr,Ce,Y)O2-like phase inhomogeneity and enhanced grain growth in sintered oxides, both of which adversely influence the ionic conductivity. This work demonstrates that Ba1−xSrxCe0.6Zr0.2Y0.2O3−δ would be a promising electrolyte for H+-SOFC applications if the Sr doping is well controlled.

This research investigates the effects of natural aging and cold working prior to artificial aging on microstructures and mechanical properties of Al-4.6Cu-0.5Mg-0.5Ag alloy. Mechanical properties relative to microstructure variations were elucidated by the observations of the optical microscope (OM), differential scanning calorimeter (DSC), electrical conductivity meter (pct IACS), and transmission electron microscopy (TEM). The results showed that natural aging treatment has little noticeable benefit on the quantity of precipitation strengthening phases and mechanical properties, but it increases the precipitation strengthening rate at the initial stage of artificial aging. Cold working brings more lattice defects which suppress Al-Cu (GP zone) and Mg-Ag clustering, and therefore the precipitation of Ω phase decreases. Furthermore, more dislocations are formed, leading to precipitate the more heterogeneous nucleation of θ′ phase. The above-mentioned precipitation phenomena and strain hardening effect are more obvious with higher degrees of cold working.

Oxides of La 0.8 Sr 0.2 Mn 1− x Ru x O 3−δ (LSMR) ( x = 0, 0.25, 0.50, 0.75, or 1.0) were prepared to fabricate cathodes in solid oxide fuel cells. The crystal structure changed from trigonal ( x = 0 or 0.25) to a mixture of trigonal and orthorhombic ( x = 0.5) and to orthorhombic ( x = 0.75 or 1.0). X-ray photoelectron spectroscopy analysis after electrochemical testing indicated that the relative concentrations of Ru 4+ to Ru 6+ and Mn 4+ to Mn 2+ influence the performance of a single cell. The transformation from Ru 4+ to Ru 6+ releases two electrons but that from Mn 4+ to Mn 2+ creates two electron holes (an oxygen vacancy). The relative concentrations in LSMR were determined using the stoichiometric ratio ( x ) of Ru, and then, the concentrations of electrons and electron holes for influencing the cathode electrochemical catalytic reactivity were estimated. x = 0.25 represented the better cell performance, and Ru may stabilize the LSMR grain size during electrochemical testing.

An innovative proton exchange membrane fuel cell was assembled using Au-coated nickel foam instead of the conventional flow field (carbon plate). The effect of operational parameters on the performance of this cell was investigated by DC polarization and electrochemical impedance spectroscopy techniques. Parameters such as cell operating temperature, cathode humidification temperature, and cathode-gas stoichiometry were of concern. Our results indicate that the testing temperature is increased from 40 °C to 60 °C, the power density increases, charge-transfer resistance decreases. When the cathode humidification temperature increases from 50 °C to 70 °C, the power density decreases. This is ascribed to an increase in mass-transfer resistance of the cell from 0.009 to 0.032 Ω, possibly because of partial flooding. The cell also performs better if cathode-gas stoichiometry is increased from 2 to 5. A maximum power density of 791.6 mW/cm 2 was realized under the following optimal conditions: a testing temperature of 60 °C, cathode humidification temperature of 50 °C, and cathode-gas stoichiometry of 5.

a b s t r a c t Al-doped zinc oxide (AZO) transparent conductive films were prepared on a glass substrate using a magnetron sputtering system with a pure zinc oxide (ZnO) target and a pure Al tar- get sputtered using radio frequency (RF) power. The RF power was set at 100 W for the ZnO target and varied from 20 to 150 W for the Al target. The morphology of the thin films was examined by field-emission scanning electron microscope (FE-SEM), and their composition was analyzed by the equipped energy-dispersive X-ray spectroscopy (EDS). The cross section of the films determined through FE-SEM indicated that their thickness was around 650 nm. EDS analy- sis revealed that the Al-dopant concentration of the AZO films increased in the following order: 0.85 at.% (20 W) < 1.60 at.% (40 W) < 3.52 at.% (100 W) < 4.34 at.% (150 W). Analysis of the films using X-ray diffractometer (XRD) indicated that all films had a wurtzite structure with a texture of (0 0 2). High-resolution transmission electron microscopy (HRTEM) revealed a number of defects in the films, such as stacking faults and dislocations. Ultraviolet photoelectron spectroscopy (UPS) was used to estimate the optical energy gap (Eg) for the AZO thin films. The energy gap increases from 3.39 to 3.58 eV as the RF power applied to the Al target increase. The electrical resistivity of the films decreased from 3.43 × 10 −2 � cm to 3.29 × 10 −3 � cm as the RF power increased from 20 to 150 W when a four-point probe was used to investigate. Atomic force microscope (AFM) revealed that the surface roughness of the films increased with increasing RF power. The average optical transmittance of the films was determined by UV-visible spectrometer. The films are suitable for use as transparent conductive oxide films in the optoelectronic industry. A decrease in the electrical resistivity of the film with increasing Al-dopant con- centration was ascribed to an increase in the carrier concentration and density of stacking faults in the films.

A novel method to improve the cycling capacity degradation of Mg 2 Ni-based hydrogen storage alloy by means of composite materials has been proposed. The new composites Mg 2 Ni- x mol% Mg 3 AlNi 2 ( x = 0, 15, 30, 60, 100) were prepared by means of combining electric resistance melting with isothermal evaporation casting process (IECP). Phase analysis and microstructure were investigated by SEM and TEM observations. Results showed that the cycling stability of the alloy with Mg 3 AlNi 2 was superior to that of Mg 2 Ni. XPS analysis revealed that the formation of an Al oxide film during cycling could enhance the anti-corrosion of the surface of the composites. Among the obtained capacity retaining rates, Mg 2 Ni-15 mol% Mg 3 AlNi 2 composite had the best anti-corrosion performance. This composite has kept 76% of its maximum discharge capacity (50 mA hg −1 ) at 25th cycle compared to 20% for Mg 2 Ni. The enhancement of the cycling stability of the electrode alloy with 15 mol% Mg 3 AlNi 2 can be ascribed to the decrease in the rate of pulverization of the alloy during cycling, which is considered as the factor in the improvement of the electrochemical properties of the Mg 3 AlNi 2 -containing alloys.

Corrosion of nickel, copper, and 316 stainless steel in aluminum chloride/1-ethyl-3-methylimidazolium chloride ionic liquid (IL) is investigated by means of electrochemical techniques. SEM analyses are performed to examine the reaction mechanisms. While Ni shows good stability, Cu has high corrosion susceptibility in this IL. For 316 steel, pitting corrosion occurs at a lower potential than that of passivation. In the non-aqueous, low-oxygen, and high-ion-containing IL, the material corrosion properties are totally different from those found in conventional environments. Since ILs have found increasing potential in diverse applications, new corrosion prevention strategies are needed to overcome the IL-derived material corrosion problems.