Copper(I) oxide (Cu2O) is a very favorable p-type semiconductor. It is an appealing candidate for photoelectrochemical water splitting. Here we report the fabrication and performance of gold (Au) underlayer–Cu2O composite photocathode for photoelectrochemical water splitting. The composite photocathode was fabricated by the electrodeposition technique. The different morphologies of the Au underlayer were achieved via variation in the process parameters including applied potential, electrolyte pH, and the presence of L-cysteine in the electrolyte. The Cu2O overlayer was also deposited using electrodeposition. Additionally, the influence of morphology variation, of the Au underlayer, on the performance of the composite photocathode was evaluated. It was observed that the performance of the composite photocathode increased by 81% when compared to a control sample of Cu2O. The composite photocathodes were characterized by scanning electron microscopy, X-ray diffraction, and electrochemical impedance spectroscopy.

A “RE-free” and I-phase-containing Mg–8Sn-based alloy system was developed and successfully fabricated through the equal channel angular pressing (ECAP) process. The influence of the Zn/Al mass ratio on the microstructures and mechanical properties of the as-ECAPed Mg–8Sn–(5,6,7)Zn–2(wt%)Al alloys was investigated using an optical microscope, an X-ray diffractometer, a scanning electron microscope, a transmission electron microscope, and a universal testing machine. Grain size, dynamic recrystallization behavior, and texture were found to be greatly affected by the Zn/Al mass ratio. Furthermore, the ultimate tensile strength (250 MPa) and elongation (14.5%) of the alloy with a Zn/Al mass ratio of 3 were considerably increased compared to those of the as-ECAPed alloys with Zn/Al ratios of 2.5 and 3.5 (ultimate tensile strength and elongation of 215 MPa and 13% and 184 MPa and 10%, respectively). This significant enhancement was attributed to extensive grain boundary strengthening, precipitation strengthening, and higher work hardening capacity as well as texture randomization. The strength and ductility of the as-ECAPed alloys are also discussed in terms of the I-phase and Mg2Sn formation.

A novel hybrid processing has been developed to achieve dense and crack-free mullite films with large critical thicknesses. The amorphous solid nanoparticles obtained from the mullite sol–gel precursor were mixed with the same liquid precursor to form stable suspensions, which were subsequently used to form mullite coatings with the dip-coating method, followed by drying and firing. The hybrid precursor suspensions resulted in highly close-packed nanoparticles, which reduced shrinkage during sintering. Selecting the solvent with a low evaporation rate and high surface tension can effectively eliminate the surface instability caused by the lateral flow during solvent evaporation. The mullite film density was significantly improved at low sintering temperatures, because of the high packing density and viscous flow at above the glass transition temperature of the amorphous gel nanoparticles before crystallization. Dense and crack-free mullite films with 500–600 nm thickness can be obtained from the novel hybrid approach.

Spark plasma sintering (SPS) is adopted to fabricate transparent AlON ceramics at 1350–1500 °C under 40 MPa, using a bimodal γ-AlON powder synthesized by the carbothermal reduction and nitridation method. After holding 10 min, high density samples are obtained, and their optical transmittance is investigated over the wavelength range of 1330–6000 nm. Despite the samples SPS-processed at 1350 °C indicate the presence of three-phases: γ-AlON, α-Al2O3, and h-AlN, they show high infrared transparency, i.e., the maximum transmittance for 1.2 mm thick specimens is up to 77.3% at ∼3900 nm. Also, the processed samples exhibit high hardness of 17.81 GPa. The high infrared transmittance should be mainly attributed to high density and rationally controlled grain size distribution, and the high hardness is apparently caused by a small grain size.

The present study was focused to investigate mechanical properties of ZnO thin films deposited on fused quartz substrates at different sputtering deposition pressures (5, 10, 15, and 20 mTorr) using DC sputtering. The crystallinity and microstructure show a marked influence on the mechanical properties of ZnO thin films. The structural evolution of the thin films is in (002) plane and influenced by deposition pressure. The intensity of (002) peak of the films rises initially and decreases with further increasing deposition pressure. The mechanical properties such as hardness, Young’s modulus, and coefficient of friction of ZnO thin films were measured using three-sided pyramidal Berkovich nanoindentation. The adhesion strength of thin films was measured by using scratch test under ramp loading. Load–displacement profile of thin films at continuous indentation cycle without any discontinuity revealed no fracture, cracking event, and defects, which is a consequence of dense microstructure and good adherence of films to the substrate.

Zr–Co–Al alloys possess prospects of wide applications in the field of nuclear reactor cladding materials and biomedical materials. (Zr0.5Co0.5)100−x Alx (x = 1, 2, 3 at.%) alloys were prepared by the water-cooling copper mold suction casting technique, and the microstructure and compression mechanical properties of the alloys were investigated. The results showed that the as-cast Zr–Co–Al alloys mainly consisted of the B2 ZrCo phase with columnar or equiaxed grains and a small quantity of intermetallic compounds, i.e., Co2Zr and Zr2Co. The yield strength of Zr–Co–Al alloys increased with increasing Al content, but the plasticity decreased at the same time. The as-cast Zr49.5Co49.5Al1 alloy attained the highest ultimate compression strength up to 2.57 ± 0.02 GPa and the largest compression strain up to ∼54.7%. The B2 to B33 martensitic transformation that occurred during the deformation process was investigated using high resolution transmission electron microscopy. It was concluded that the enhanced plasticity of Zr49.5Co49.5Al1 alloy can be attributed to the transformation induced plasticity associated with the deformation-induced martensitic transformation.

A series CeO2/Al2O3 catalysts was modified with rare earth element (La, Nd, Sm, Gd, and Tm) using extrusion method. The catalytic activities of the obtained catalysts were measured for the selective catalytic reduction (SCR) of NO with NH3 to screen suitable addition of rare earth element. These samples were characterized by X-ray diffraction (XRD), N2 adsorption (N2-BET), NH3 temperature-programmed desorption analyses (NH3-TPD), H2 temperature-programmed reduction (H2-TPR), Raman spectra, pyridine adsorption Fourier-transform infrared (Py-IR) and X-ray photoelectron spectroscopy (XPS), respectively. Results showed that the CeO2/Al2O3 exhibited excellent performance in resisting reactant poisoning caused by vapor and sulfur and the highest catalytic activity (98.35%) at 360 °C when the added Tm/Ce molar ratio is 0.10. The surface acidity of CeO2/Al2O3 catalyst would be enhanced with the addition of rare earth ions. Consequently, rare earth ion was beneficial to catalytic activity at low temperatures and corresponded to similar law. Analysis revealed that the higher number of acid sites and the more Ce3+ were conductive to obtain the excellent NH3-SCR activity.

The propagation of a pre-existing center crack in single crystal tungsten under cyclic loading was examined by molecular dynamics (MD) simulations at various temperatures. The results indicated that the deformation mechanism and fracture behavior at crack tip were differences for variously oriented cracks. The [001](010) crack propagated as the form of the formation of slip, while the deformation mechanisms of [10−1](101) crack were blunting voids at 300 K. At higher temperature, many more slip systems were activated resulting in the change of mode of crack propagation. Simulated results showed that the effect of temperature on deformation mechanism and fracture behavior of [001](010) crack was more sensitive than that of [10−1](101) crack. Meanwhile, the influence of a 5〈310〉{110} model grain boundary (GB) on crack propagation was also discussed. Detailed analysis showed that the grain boundary resisted the crack growth by changing the deformation mechanisms and the path of crack propagation at crack tip before the crack reached the grain boundary, and had an important influence on the crack growth rate.

To achieve the first demonstration of non-polar a-plane gallium nitride (GaN) epitaxy on (0 1 0) gallium oxide substrates by metal organic chemical vapor deposition (MOCVD), a low temperature AlGaN nucleation layer was engineered. Specific low temperature AlGaN growth parameters were necessary because the gallium oxide substrate begins to decompose at ∼600 °C in the ambient of H2. To achieve a smooth GaN epitaxial surface, low V/III molar ratio, and low pressure were required. To characterize the GaN film, AFM along with an orientation-dependent crystal tilt mosaic study by X-ray diffraction was performed. We effectively reduced threading dislocation density by applying in situ SiN interlayers grown by MOCVD. The oxygen contamination in the GaN film was found to originate from the substrate decomposition during GaN growth and can be reduced more than 10 times by using GaN buffer layer grown under N2 ambient.

It is desirable to evaluate the ratcheting behavior of biomedical magnesium under cyclic loading with and without precorrosion, due to the promising future in biomedical implant field. This study focuses on the investigation of the uniaxial ratcheting strain evolutions of ZEK100 magnesium alloy sheet under various loading conditions and different corrosion time. To illustrate the ratcheting response in detail, the effects of several factors on the ratcheting strain evolution were discussed, including mean stress, stress amplitude, specimen orientations, loading history, and precorroded duration. A series of asymmetrical multistep stress-controlled ratcheting tests were conducted. The mean stress, stress amplitude, and precorrosion duration have significant influence on the ratcheting response of material. ZEK100 magnesium alloy is sensitive to loading history. ZEK100 magnesium alloy exhibits anisotropic behavior, and it is found that the final ratcheting strain of transverse direction (TD) specimens is always larger than that of rolling direction (RD) specimens. The corrosion behavior of ZEK100 magnesium alloy in phosphate buffered solution (PBS) simulated physiological environment was also studied. The corrosion process is characterized by pitting corrosion, and the corrosion rate of material stabilizes at about 2.4 g/(m2 d) after an exponentially decrease at initial stage.

The unloading part of a load–displacement curve from instrumented indentation tests is usually approximated by a power law (Oliver and Pharr model), where the load is the dependent variable. This approach generally fits well the data. Nevertheless, the convergence is occasionally quite questionable. In this regard, we propose a different approach for the Oliver and Pharr model, called the inverted approach, since it assigns the displacement as the dependent variable. Both models were used to fit the unloading curves from nanoindentation tests on fused silica and aluminum, applying a general least squares procedure. Generally, the inverted methodology leads to similar results for the fitting parameters and the elastic modulus (E) when convergence is achieved. Nevertheless, this approach facilitates the convergence, because it is a better conditioned problem. Additionally, by Monte Carlo simulations we found that robustness is improved using the inverted approach, since the estimation of E is more accurate, especially for aluminum.

A pure and (Fe–Ni) doped tin oxide thin films were formed on glass substrates by sol–gel dip coating method. Some characterization techniques are used as X-ray diffraction (XRD), UV–vis spectroscopy and atomic force microscopy (AFM) to study the effect of method conditions and dopants on the structural, morphological, and optical properties of thin films. According to XRD results, no phase attributed to Fe or Ni were detected, which suggests the incorporation of Fe and Ni in SnO2 network. All the diffraction peaks can be assigned as rutile phase of pure SnO2 except (111) is attributed to cubic phase. The optic analyses have shown an average transmittance between 70 and 90%, and showed a direct band gap reducing with increase in Fe doping (3.82–3.72 eV) and Ni content (3.82–3.69 eV). AFM images have revealed that surface roughness is affected strongly by deposition conditions and dopant contents.

High-porosity metakaolin-based geopolymer foams (GFs) were fabricated by a gelcasting technique using hydrogen peroxide (foaming agent) in combination with Tween 80 (surfactant). Slurries processed in optimized conditions enabled to fabricate potassium based GFs with a total porosity in the range of ∼67 to ∼86 vol% (∼62 to ∼84 vol% open), thermal conductivity from ∼0.289 to ∼0.091 W/mK, and possessing a compressive strength from ∼0.3 to ∼9.4 MPa. Moreover, factors that influence the compressive strength, the porosity, the thermal conductivity, and the cell size distribution were investigated. The results showed that the cell size and size distribution can be controlled by adding different content of surfactant and foaming agent. The foamed geopolymer can also be used as adsorbents for the removal of copper and ammonium ions from wastewater. The foams, due to their low thermal conductivity, could also be used for thermal insulation. It was also possible to produce geopolymer formulations that could be printed using additive manufacturing technology (Direct Ink writing), which enabled to produce components with nonstochastic porosity.

The successful and widely used two-step process of producing the hybrid organic-inorganic perovskite CH3NH3PbI3, consists of converting a solution deposited PbI2 film by reacting it with CH3NH3I. Here, we investigate the solidification of PbI2 films from a DMF solution by performing in situ grazing incidence wide angle X-ray scattering (GIWAXS) measurements. The measurements reveal an elaborate sol–gel process involving three PbI2⋅DMF solvate complexes—including disordered and ordered ones—prior to PbI2 formation. The ordered solvates appear to be metastable as they transform into the PbI2 phase in air within minutes without annealing. Morphological analysis of air-dried and annealed films reveals that the air-dried PbI2 is substantially more porous when the coating process produces one of the intermediate solvates, making this more suitable for subsequent conversion into the perovskite phase. The observation of metastable solvates on the pathway to PbI2 formation open up new opportunities for influencing the two-step conversion of metal halides into efficient light harvesting or emitting perovskite semiconductors.

Modern hydrogen technology requires materials with high capacity storage. Many metals and alloys form cheap metal hydrides that can contain a high volume density of hydrogen. The quaternary alloy Cr–Fe–Ti–Zr with Laves phases is one promising hydrogen storage material. Understanding phase equilibria properties is essential to improve the Laves phases’ hydrogen storage capacity. In this work, the thermodynamic description of two constituent ternary phase materials, Cr–Ti–Zr and Fe–Ti–Zr are investigated using the Calphad method. A set of Gibbs energies was optimized during this work and good agreement between modeling and available experimental information was found. Moreover, a new thermodynamic model for a binary Fe–Zr system was developed based on recent experimental investigation about intermetallic compounds FeZr2 and FeZr3. Obtained in this work results can find application in development of new hydrogen storage materials.