Recently, a new boron allotrope B52 with orthorhombic structure was theoretically predicted to be more stable than α-tetragonal boron B50. In experiments however, only tetragonal boron phases have been obtained so far. Here, we report for the first time on the preparation of orthorhombic boron phase of B52-type, space group Pnnn, a = 8.894 Å, b = 8.784 Å, c = 5.019 Å, by normal-pressure annealing of α-tetragonal boron, synthesized at high pressures by pyrolysis of decaborane, B10H14. We have investigated temperature-induced structure evolution and thermal desorption of boron samples, which allowed us to regard the structure of mother “α-tetragonal boron” as a boron-rich hydride with composition close to B51.5H7.7. In accordance with density-functional theory calculations, the most preferable sites of hydrogen placement in tetragonal unit cell are 8j and 4g; the tetragonal-to-orthorhombic transition takes place spontaneously upon complete dehydrogenation.

Conventional retrogression and re-aging (RRA) treatment could not be put to good use for combination property of Al–Zn–Mg–Cu alloys. The new RRA treatment fitted for spray formed Al–Zn–Mg–Cu alloy was investigated by transmission electron microscope, tensile, and conductivity tests. The results show that the pre-aging treatment with under aging of 120 °C for 16 h is beneficial for the redissolution of matrix precipitates during retrogression treatment. With the retrogression of 200 °C for 8 min, grain boundary precipitates are discrete and the corrosion resistance of the alloy is drastically increased. After re-aging (120 °C for 24 h) the strength of the alloy is increased again. According to the above-mentioned new RRA treatment, the ultimate tensile strength, yield strength, elongation, and conductivity of the alloy are 791 MPa, 736 MPa, 8.5%, and 39.5% IACS respectively, which is higher than that after conventional RRA treatment.

DNA-immobilized Fe3O4 particles (DNA–Fe-particles) were prepared by mixing DNA, magnetic Fe3O4 particles, and the silane coupling reagent, bis[3-(trimethoxysilyl)propyl]amine. The DNA–inorganic hybrid material was uniformly immobilized onto magnetic Fe3O4 particles with the diameters of approximately 450 nm. These DNA–Fe-particles were stable in water. Additionally, we could simply collect the DNA–Fe-particles by a magnet from an aqueous solution. Therefore, we demonstrated the accumulation of various metal ions, such as heavy and rare-earth metal ions, by the DNA–Fe-particles. As a result, although these DNA–Fe-particles could selectively accumulate heavy and rare-earth metal ions, these materials could not accumulate the light metal ions, such as Mg(II) and Ca(II) ions. Furthermore, the metal ion-accumulated DNA–Fe-particles could be recycled by washing them with an aqueous ethylenediaminetetraacetic acid solution.

Diethyl ether is widely used in the fields of diesel engines, agriculture, food, chemical, biological, pharmaceutical, and medical industries. It is necessary to carry out real-time monitoring of this molecule due to its harmful effects on human health. In this study, a highly sensitive SnO2/rGO gas-sensing material has been prepared by a hydrothermal method. The surface adsorption and reaction processes between the SnO2/rGO gas-sensing film and diethyl ether have been studied by the in situ diffuse-reflectance Fourier-transform infrared spectroscopy at different temperatures. The results show that the SnO2/rGO gas-sensing material has high sensitivity to diethyl ether, and the lowest detection limit can reach 1 ppm, and that ethyl $\left( {{\rm{C}}{{\rm{H}}_{\rm{3}}}\mathop {{\rm{C}}{{\rm{H}}_{\rm{2}}}}\nolimits^ \cdot } \right)$, oxethyl $\left( {{\rm{C}}{{\rm{H}}_{\rm{3}}}{\rm{C}}{{\rm{H}}_2}{{\rm{O}}^ \cdot }} \right)$, ethanol (CH3CH2OH), formaldehyde (HCHO), acetaldehyde (CH3CHO), ethylene (C2H4), H2O, and CO2 surface species are formed during diethyl ether adsorption at different temperatures. A possible mechanism of the reaction process is discussed.

A bilayer film deposition process for synthesizing ultrathin amorphous carbon (a-C) films with structure and properties dominated by those of the sp3-rich bulk layer was developed in this study. This was accomplished by incorporating in conventional filtered cathodic vacuum arc (FCVA) deposition a low-ion-energy pre-deposition step (no substrate biasing) leading to the formation of an ultrathin (<1 nm) carbon layer and a post-deposition step of high-energy Ar+ ion sputtering resulting in film thinning. The thickness and cross-sectional structure of hydrogen-free a-C ultrathin films synthesized by this multistep FCVA process under optimum substrate bias conditions (−100 V pulsed bias voltage) were examined by high-resolution transmission electron microscopy and electron energy loss spectroscopy. The bilayer a-C films synthesized under these conditions exhibit slightly higher sp3 fractions and interface and bulk layers significantly thinner and thicker, respectively, compared with single-layer a-C films of similar thickness deposited under the same FCVA conditions.

Multilayered thin films of Al/Cu/Fe have been prepared by magnetron sputtering and annealed into quasicrystalline and approximant phases on Al2O3 and Si substrates, respectively. The nanomechanical and nanotribological properties, such as hardness, elastic modulus, friction, and toughness, have been measured using a triboindenter and analytical methods. The approximant phase was proved to be slightly harder than the quasicrystalline phase with a hardness of about 15.6 GPa, and with a similar elastic modulus of about 258 GPa. These values however decreased rapidly with an increasing amount of Si in the approximant. The indentation toughness of the approximant, <0.1 MPa/m½, was however inferior to that of the quasicrystals with 1.5 MPa/m½. Friction coefficients were measured in a range of 0.10–0.14 for both the quasicrystalline and approximant thin films.

The effects of rare earth oxide Y2O3 additive on microstructure and mechanical properties of proeutectoid ferrite/granular bainitic coating by flux-cored arc welding were investigated. The results show that the primary austenite in the bainitic coating can be refined by Y2O3. The grain size of primary austenite is decreased from 51.2 µm to 40.1 µm with the increased Y2O3. The size of proeutectoid ferrite is decreased significantly and the fraction of the bainite is increased, which in turn facilitates the uniform distribution of the M/A island. Large number of the dislocation martensite is transformed into M/A. With the increased Y2O3 additive, the hardness and the tensile strength of the coating increases from HV 272 ± 13 to HV 312 ± 8 and from 764 ± 10 MPa to 885 ± 12 MPa, respectively. Moreover, the wear resistance of the coating with Y2O3 additive is increased simultaneously.

Influence of corrosion/fatigue factors on the fatigue life of 7B04-T6 aluminum alloys were studied in this paper. Different kinds of alternating corrosion-fatigue tests were carried out. Three factors influencing fatigue life were investigated: pre-corrosion time, corrosion/fatigue alternation frequency, and specimen’s size. The results show that: with the extension of pre-corrosion time, fatigue lives decreased; although the total corrosion time was the same (192 h), as the corrosion/fatigue alternation frequency increased, the total fatigue lives increased. The total fatigue lives of specimens subjected to two, four, and six corrosion/fatigue cycles (n = 2, 4, 6), in which specimens underwent pre-corrosion for 96 h per cycle (n = 2), 48 h per cycle (n = 4), and 32 h per cycle (n = 6), respectively, was measured. It was found that the fatigue lives increased by 56.4, 84.4, 136%, as the number of cycles increased, compared to tests in which no alternation took place (192 h of continuous corrosion). When exposed to the same corrosion times, different sized specimens demonstrated different fatigue lives. The fatigue lives of small specimens were shorter than the larger specimens. These results are all due to the specific properties of corrosion/fatigue factors.

Generally, the obvious work hardening, dynamic recrystallization (DRX), and dynamic recovery behaviors can be found during hot deformation of Ni-based superalloys. In the present study, the classical dislocation density theory is improved by introducing a new dislocation annihilation item to represent the influences of DRX on dislocation density evolution for a Ni-based superalloy. Based on the improved dislocation density theory, the peak strain corresponding to peak stress and the critical strain for initiating DRX can be determined, and the improved DRX kinetics equations and grain size evolution models are developed. The physical framework and algorithmic idea of the improved dislocation density theory are clarified. Moreover, the deformed microstructures are characterized and quantitatively correlated to validate the improved dislocation density theory. It is found that the improved dislocation density-based models can precisely characterize hot deformation and DRX behaviors for the studied superalloy under the tested conditions.

Visible-light responsive plasmonic Ag2O/Ag/g-C3N4 nanosheets (NS) were successfully prepared by a simple and green photodeposition method. The obtained composites were characterized by XRD, Fourier transform infrared, transmission electron microscopy, UV-vis, and the photoluminescence (PL) results indicated that the Ag2O/Ag/g-C3N4 NS composites showed better photoabsorption performance than g-C3N4 due to the surface plasmon resonance effect of Ag nanoparticles. Meanwhile, the composite exhibited excellent photocatalytic activities, which was ∼3.8 and ∼3.0 times higher than those of bulk g-C3N4 and pure g-C3N4 NS, respectively. Moreover, the as-prepared composites showed a high structural stability in the photodegradation of Rhodamine B. A possible photocatalytic and charge separation mechanism was suggested based on the PL spectra and the active species trapping experiment.

Titania nanotube arrays were synthesized electrochemically by anodization of titanium foils, and the synthesized titania nanotubes were then implanted with indium ions. The effect of In-ions implantation on crystallization and phase transformation of titania was investigated using in-situ high-temperature X-ray diffraction and synchrotron radiation diffraction from room temperature to 1000 °C. Diffraction results show that crystalline anatase first appeared at 400 °C in both the non-implanted and the In-implanted materials. The temperature at which crystalline rutile temperature appeared was 600 °C for non-implanted materials and 700 °C for In-implanted materials, and the indium implantation inhibited the anatase-to-rutile transformation. Although In3+ is expected to increase oxygen vacancy concentration and then the rate of titania transformation, the observations are consistent with implanted In-ions occupying the Ti sublattice substitutionally and then inhibiting the transformation. The relatively difficult anatase-to-rutile transformation in the In-implanted material appears to result from the relatively large In3+ radius (0.080 nm). The In3+ partly replaces the Ti4+ (0.061 nm), which provides a greater structural rigidity and prevents relaxation in the Ti bonding environment.

Pr2−x Cex CuO4+δ thin films were grown hetero-epitaxially on (001) SrTiO3 substrates using ozone-assisted molecular beam epitaxy. High-quality epilayers with a cerium concentrations of x = 0.15 were grown and characterized electrically, structurally, and by magnetization measurements. The Pr2−x Cex CuO4+δ films were found to maintain the tetragonal Nd2CuO4 (T′) crystal structure with a linear dependence of lattice constant on the Ce concentration. The superconductivity of the Pr2−x Cex CuO4+δ films was maintained up to x ≈ 0.23 with a T c up to 12.6 K. For x < 0.15, control of the oxygen concentration δ by annealing is crucial for the induction of superconductivity in Pr2−x Cex CuO4+δ and this still holds for x > 0.20. We show that the electron mean free path length $\ell$ may be significantly enhanced by optimizing those annealing conditions. Moreover, the enhancement of $\ell$ leads to a reduction of the upper critical field, suggesting that superconductivity of Pr2−x Cex CuO4+δ is to be considered in the clean limit.

Novel mixed micelle was successfully fabricated by the synergistic self-assembly of poly(methacrylate isobutyl polyhedral oligomeric silsesquioxane (POSS)-co-N-isopropylacrylamide-co-oligo(ethylene glycol)methyl ether methacrylate-co-acrylic acid) (P(methacrylate isobutyl (MAPOSS)-co-NIPAM-co-OEGMA-co-AA)) and poly(methacrylate isobutyl POSS-co-N-isopropylacrylamide-co-oligo(ethylene glycol) methyl ether methacrylate-co-2-vinylpyridine) (P(MAPOSS-co-NIPAM-co-OEGMA-co-2VP)). Dynamic light scattering (DLS) and transmission electron microscopy characterizations demonstrate that the formation of mixed micelles is driven by electrostatic interaction. The formation of the mixed micelles was further implied by a simple fluorescence resonance energy transfer based technique. The mixed micelle possesses the biggest size at pH = 7.0, which is attributed to the strongest electrostatic interaction between the two kinds of micelles. The zeta potential under different pH was detected to further investigate the surface charges corroborating the discussions. DLS and UV-vis indicate that the lower critical solution temperature (LCST) is pH dependent. The mixed micelles reach the highest LCST at pH 7.0. The LCST of the mixed micelle can be tuned by adjusting the volume ratio of the two kinds of micelles as well. Moreover, the thermo-responsive behavior of the mixed micelle is absolutely reversible.

Near-infrared (NIR) absorption in solar-control LaB6 nanoparticles (NPs) is derived from the localized surface plasmon resonance (LSPR) at 1.3 eV, and accompanies an unclarified subpeak at 1.8 eV. As an origin of this subpeak, a disk-like particle shape of LaB6 NP has recently been proposed, besides the previously-proposed, milling-derived LaO phase. A series of heating experiments at 200–850 °C in air for LaB6 NPs pulverized with different media beads have been made, followed by x-ray diffraction and transmission electron microscopy observations, to clarify that LaB6 NPs oxidizes to amorphous phases B2O3 and La–B–O at 450–600 °C, and crystallize to LaB3O6 at 650–750 °C, without forming LaO or La2O3. Dielectric functions of LaO have been derived by first-principles calculations using sX-LDA, and Mie scattering calculations have been made for various sizes, shapes, and the ensembles, showing that LaO NPs, if existed, should exhibit an excessively-broadened absorption band with a blunt LSPR peak at 2.1 eV buried in several interband-transition absorptions at 1.2–4.0 eV. These analyses confirm that the observed 1.8 eV subpeak could not originate from LaO and support the nonspherical shape of NPs as the origin of the subpeak.

We designed a clamped beam bending test using a nanoindentation holder with help of transmission electron microscopy (TEM) and focused ion beam specimen fabrication. The microstructure evolution and crack propagation in nanocrystalline TiN were studied by electron imaging and load–displacement measurements during mechanical loading. By measuring the loads under which the crack starts and stops propagating and the time, we obtained the film's fracture toughness using the finite element method and crack propagation speed. Among these, we identified three types of crack propagation pathways, namely bridging, intergranular and a mixed mode of transgranular and intergranular fracture, and the associated microstructure changes. The measured fracture toughness is in agreement with the reported values. Thus, our in situ TEM bending test provides the first direct measurement of fracture toughness in a TEM and a correlation of fracture toughness with fracture toughening mechanisms in nanocrystalline TiN. The method is general and can be applied to other nanocrystalline materials.

Here we report on the photocurrent response of two-dimensional (2D) heterostructures of sputtered MoS2 on boron nitride (BN) deposited on (001)-oriented Si substrates. The steady state photocurrent (I ph) measurements used a continuous laser of λ = 658 nm (E = 1.88 eV) over a broad range of laser intensities, P (∼1 μW < P < 10 μW), and indicate that I ph obtained from MoS2 layers with the 80 nm BN under layer was ∼4 times higher than that obtained from MoS2 layers with the 30 nm BN under layer. We also found super linear dependence of I ph on P (I ph ∝ P γ, with γ > 1) in both the samples. The responsivities obtained over the range of laser intensity studied were in the order of mA/W (∼12 and ∼2.7 mA/W with 80 nm BN and 30 nm BN under layers, respectively). These investigations provide crucial insight into the optical activity of MoS2 on BN, which could be useful for developing a variety of optoelectronic applications with MoS2 or other 2D transition metal dichalcogenide heterostructures.

This paper presents a periodic density functional theory study on the adsorption of H, CO, and OH on Pt2Ru3 alloy surfaces containing different conformations of Pt and Ru atoms. The results show that for separate adsorption, H is preferentially adsorbed at Pt sites, whereas CO and OH are preferentially adsorbed at Ru sites. The adsorption strengths of H, CO, and OH are affected by ratio of the alloying atoms in top surface, the nature of the neighboring atom nearest to the adsorption site, and the conformation of alloying atoms in subsurface. We also investigated the coadsorption of CO with OH and the coadsorption of CO with H and found that the Pt–CO bond strength weakens. We also uncovered some information about the competitive adsorption behavior of adsorbates (CO, OH) with the aim of designing CO-tolerant Pt–Ru alloy catalysts.

The double perovskite Tb2MnCoO6 and two simple perovskites TbMnO3 and TbCoO3 were synthesized by a solid sintering reaction method. The Rietveld refinement results based on the x-ray powder diffraction data identified all samples as orthorhombic perovskite structures with space group Pbnm (62). The lattice parameters of Tb2MnCoO6 were a = 5.278 (3) Å, b = 5.579 (4) Å, and c = 7.513 (4) Å with a cell volume V = 221.2 (6) Å3, Z = 2. Meta-magnetic behavior was observed near 92 K for Tb2MnCoO6, which was considered to be related to the coexistence of and competition between the ferromagnetic order and antiferromagnetic order. Temperature-dependent resistance (R–T) was also measured. Compared with TbCoO3 and TbMnO3, Tb2MnCoO6 is more conductive, with its activation energy reduced from 0.3062 eV for TbCoO3 (0.2754 eV for TbMnO3) to 0.1949 eV. The results reported here can assist in understanding the multiferroic physics mechanism of double perovskite materials.

Novel nanogranular flakes in which magnetic metallic nanoparticles are highly dispersed in an oxide matrix were fabricated for use as a constituent material in bulk nanogranular composites. A simple milling process using core/shell nanoparticles of magnetic metal/oxide was used to produce nanogranular flakes composed of magnetic metallic nanoparticles in an oxide matrix. The high dispersion of the metallic nanoparticles in the oxide matrix increased the electrical resistivity of the flakes. In addition, neighboring nanoparticles in the flakes interacted with each other via magnetic exchange coupling, and the flakes exhibited good soft magnetism with low coercivity when they contained a high concentration of highly dispersed magnetic metallic nanoparticles. The coercivity of the flakes could be decreased significantly by annealing and by modifying the surface of the flakes. A minimum coercivity of 8.7 Oe was obtained using flakes with a composition of Fe0.5Ni0.5–4 wt% Si.

Evidences show that the composition of β″ formed in age hardening of Al alloys should be the prototype Mg5Si6 with Al and/or Cu addition. In the present work, molecular dynamics simulations are carried out to investigate the influence of the addition of Al and/or Cu to the mechanical properties of the prototype Mg5Si6. Our simulations imply that Mg5Si6 with both Al and Cu addition has relatively poor mechanical performance when compared with other three models. The snapshots of atomic configurations during uniaxial tension test illustrate that only if both Al and Cu dissolve in β″, clusters can form through Al atoms segregating around Cu atoms, thus applying different stress fields on the Al matrix, resulting different mechanical properties in comparison with other three β″ models.