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In this work, the self-ion irradiation behavior of nanocrystalline copper-tantalum alloys was investigated. In particular, the microstructural evolution of Cu-3at.%Ta and Cu-10at.%Ta was evaluated under the fluence of 2 × 1017 ions/cm2 of 4 MeV Cu-ions at different temperatures. Results revealed that despite the ability of Cu-10Ta to reprecipitate new nanoclusters and thereby increase the sink density by ∼17%, it undergoes significant microstructural evolution. On the other hand, Cu-3Ta exhibits a relatively more stable microstructural response and 3.5 times less swelling over the same conditions. This result illustrates the premise that irradiation and deformation may be coupled to stabilize/rejuvenate Ta-nanoclusters in extreme-environments. [Display omitted] [ABSTRACT FROM AUTHOR]

The fusion research activities at Southwestern Institute of Physics (SWIP) include the HL-2A & HL-2M tokamak programs, fusion reactor design and materials, along with key fusion technologies including R&D on ITER procurement packages. This paper presents the progress of fusion technology at SWIP, including the ITER first wall and blanket, Chinese helium cooled ceramic breeder test blanket module (HCCB–TBM) for ITER, gas injection system and gas discharge cleaning system, as well as the recent activities on reactor materials and R&D related to advanced divertor. The final design for ITER first wall and blanket shielding blocks allocated to SWIP have been completed, and were validated by recent tests. Major manufacturing technologies, such as forging, deep drilling, explosion bonding and deep laser welding, have been successfully demonstrated. Furthermore, the conceptual design of CN–HCCB–TBM has been completed, the related materials’ preparation, mock-up manufacturing and tests have been implemented. The tungsten divertor has been studied with various bonding and coating technologies. Meanwhile, highlights of functional material for TBM, oxides and carbides dispersion strengthened (ODS, CDS) reduced activation ferritic/martensitic (RAFM) steel, vanadium and tungsten alloys are also presented. [ABSTRACT FROM AUTHOR]

An in-situ measurement of the particle number size distribution and optical properties (scattering and absorption coefficients) of PM 2.5 was conducted at Mt. Tai, a mountain top station in central east China in the spring of 2011. It was found that the particle size distribution, mass concentration, as well as the optical properties have been modified during the dust periods. The mean mass concentration of PM 2.5 during the dust periods was nearly twice of that during the non-dust period. The number and volume size distribution showed a higher concentration in the size range of 0.5–2.5 μm during the dust period, which were identified as dust particles. The absorption coefficient increased by ∼40%, while the scattering coefficient did not show much difference. The single scattering albedo of 0.85 during dust period was also comparable with the value of 0.89 during non-dust period. The Mie model was applied to simulate the aerosol optical properties and validated through a closure study for an intensive dust event. This study quantitatively demonstrated that dust particles contributed to nearly 63% of the scattering coefficient, while the remainder was mainly due to anthropogenic particles on dust days. The dust particles took a lower portion to the absorption, about 40%, indicating the anthropogenic particles still played a more dominant role in absorbing. This study also indicated that although there were only a few tens of dust particles during dust period, they could influence in particle optical properties significantly. [ABSTRACT FROM AUTHOR]

A potentially promising coolant/structural material pair for a liquid-metal-cooled fast reactors is lead bismuth eutectic (LBE) coolant with the ferritic/martensitic steel HT9. The challenge of deploying LBE, however, is the corrosive environment it creates for structural materials. This corrosion can be mitigated with precise oxygen content control in the LBE to allow for the growth of passive protective oxide layers on the surface of the steel. In this paper, results are reported from the Irradiation Corrosion Experiment II (ICE-II), which allowed the simultaneous irradiation of a sample while in contact with LBE. It was found that a characteristic multilayer structure with an outer Fe 3 O 4 oxide and inner FeCr 2 O 4 spinel was grown and the oxidation was significantly larger in the irradiated region when compared to the region that was only exposed to LBE corrosion. Possible mechanisms are discussed to help understand this irradiation enhanced corrosion behavior. [ABSTRACT FROM AUTHOR]

Nanoindentation methodology was used to investigate the plastic deformation characteristics, including the hardness ( H ), strain rate sensitivity (SRS, m ) and activation volume ( V * ), of Cu/Mo nanostructured metallic multilayers (NMMs) with equal layer thickness ( h ) spanning from 10 to 200 nm before and after He-implantation at room temperature. Compared with the as-deposited Cu/Mo NMMs, the irradiated Cu/Mo samples exhibited the enhanced hardness particularly at great h , which is caused by the bubble-hardening effect. Unlike the as-deposited Cu/Mo NMMs displayed a monotonic increase in SRS (or a monotonic decrease in activation volume) with reducing h , the irradiated Cu/Mo samples manifested an unexpected non-monotonic variation in SRS as well as in activation volume. It was clearly unveiled that the SRS of irradiated Cu/Mo firstly decreased with reducing h down to a critical size of ~50 nm and subsequently increased with further reducing h , leaving a minimum value at the critical h . These phenomena are rationalized by considering a competition between dislocation-boundary and dislocation-bubble interactions. A thermally activated model based on the depinning process of bowed-out partial dislocations was employed to quantitatively account for the size-dependent SRS of Cu/Mo NMMs before and after irradiation. Our findings not only provide fundamental understanding of the effects of radiation-induced defects on plastic characteristics of NMMs, but also offer guidance for their microstructure sensitive design for performance optimization at extremes. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effects of glutamine (Gln) on the growth performance and immune function of high-concentrate fattening lambs. Thirty 3-month-old male healthy Hu sheep with a similar body weight of 26.75 ± 0.65 kg were randomly selected and assigned to 3 groups with 10 lambs per group. Lambs in 3 groups were fed basic diets supplemented with 0 (control group, fed a high-concentrate diet), 0.5% (Gln1, fed a high-concentrate diet), or 1.0% (Gln 2, fed a high-concentrate diet) Gln. The pre-experimental period lasted for 15 days, and the experimental period lasted for 45 days. The obtained results showed that compared with the CON group, the Gln group showed a lower F/G from 16 to 30 d, 31–45 d, and 0–45 d (P < 0.05); increased heart weight, heart index, spleen weight, spleen index, thymus weight, thymus index, small intestine weight, and small intestine index on day 45 (P < 0.05); increased concentration of CD4+ and CD8+, CD4+/CD8+ T lymphocyte ratios, lymphocyte transformation ratio in peripheral blood, and IgG content and IL-2 ratio in plasma (P < 0.05); decreased apoptosis ratio in peripheral blood on days 15, 30, and 45 (P < 0.05). However, there was no difference in these parameters compared to the Gln group (P > 0.05). In summary, this study showed that dietary Gln supplementation may improve the immune function of lambs by providing energy to the proliferation of T cells. • Gln group showed a lower F/G from 16 to 30 d, 31–45 d, and 0–45 d (P < 0.05), increased the organ index of heart, spleen, thymus, and small intestine on the 45 days (P < 0.05). • The inclusion of Gln showed increased the CD4+ and CD8+ concentration, the CD4+/CD8+ T lymphocyte ratios, the peripheral blood lymphocytes transformation ratio, and the serum IgG and IL-2 levels (P < 0.05), and decreased the peripheral blood apoptosis ratio on the 15, 30, and 45 days (P < 0.05). • These results suggest that dietary Gln supplementation might improve the immune function of lamb by providing energy to the proliferation of T cells. [ABSTRACT FROM AUTHOR]

Misfit dislocation arrays (MDAs) at semi-coherent heterogeneous interface have been demonstrated effectiveness to trap and then outgas helium (He) for alleviating void swelling in metals, but limited by atomic-level thin film deposition that is difficult to scale-up for industrial production. In this work, we proposed an innovative strategy that could generate semi-coherent homophase interfaces in a same grain by varying surface energy density assisted by high-temperature graphene (Gr) deposition. This strategy transforms strain energy and surface energy, two originally distinctive processes into successive processes, and demonstrates experimentally and theoretically by introducing {111} copper (Cu) in a {100} Cu grain. Subsequent He implantation and electrical resistivity measurement results suggest that high-density MDAs originated at this {111}/{100} interface could form stable He nanochannels near Cu surface with Gr assistance, manifesting by ultra-low increased ratio of the electrical resistivity (i.e. ∼3800% of Cu vs. ∼90% of Gr/Cu) after He implantation. The present findings may provide a new strategy for efficiently managing He and achieving surface protection of advanced metals, merely by depositing a super-rigid material on metal surface to greatly reduce surface energy density. [Display omitted] [ABSTRACT FROM AUTHOR]

A potentially enhanced radiation resistance of nanocrystalline materials, as a consequence of the high density of interfaces and surfaces, has attracted much attention both to understand the fundamental role of these defect sinks and to develop them for high-radiation environments. Here, irradiation response of nanocrystalline A 2 Ti 2 O 7 (A = Gd, Ho and Lu) pyrochlore powders with grain sizes of 20–30 nm was investigated by 1-MeV Kr 2+ ion bombardment. In situ transmission electron microscopy (TEM) revealed that the critical amorphization fluence for each nanocrystalline compound at room temperature was greater than that for their coarse-grained counterparts, indicating an enhanced amorphization resistance. The effect of temperature on the irradiation response of one of these compounds, nanocrystalline Lu 2 Ti 2 O 7 , was further examined by performing ion irradiation at an elevated temperature range of 480–600 K. The critical amorphization temperature ( T c ) was found to be noticeably higher in nanocrystalline Lu 2 Ti 2 O 7 (610 K) than its coarse-grained counterpart (480 K), revealing that nanocrystalline Lu 2 Ti 2 O 7 is less resistant to amorphization compared to its coarse-grained phase under high temperatures. We interpret these results with the aid of atomistic simulations. Molecular statics calculations find that cation antisite defects are less energetically costly to form near surfaces than in the bulk, suggesting that the nanocrystalline form of these materials is generally less susceptible to amorphization than coarse-grained counterparts at low temperatures where defect kinetics are negligible. In contrast, at high temperatures, the annealing efficiency of antisite defects by cation interstitials is significantly reduced due to the sink properties of the surfaces in the nanocrystalline pyrochlore, which contributes to the observed higher amorphization temperature in the nano-grained phase than in coarse-grained counterpart. Together, these results provide new insight into the behavior of nanocrystalline materials under irradiation. [ABSTRACT FROM AUTHOR]

A new kind of magnesium based hydrogen storage alloy with highly developed surface (HDS) was prepared using the technique of mechanical alloying followed by alkali washing in this paper. The phase composition, morphology, hydrogen storage properties and mechanisms of the alloy thus prepared, named HDS Mg-Ni, were further investigated by multiple methods including X-ray diffraction, scanning electron microscope, Sieverts volumetric method and differential scanning calorimeter. The specific surface area, average pore size and pore volume of the alloy are 50.95 m 2 g −1 , 36.2 nm and 0.34 cc g −1 , respectively. Also, it was discovered that the HDS Mg-Ni powder takes in about 0.65 wt.% of hydrogen even at a low temperature of 323 K, at which the conventional Mg and Mg 2 Ni materials could not react with H 2 . It suggests that the highly developed surface remarkably improves the hydrogen storage properties at low temperatures. Besides, the synergistic effects between the HDS Mg-Ni powder and activated carbon(AC) on the improvement of low-temperature behaviors were discussed. The results showed that the addition of AC further improves the hydrogen capacity and absorption kinetics due to the increased specific surface area, providing easier and more paths for the diffusion of hydrogen into the alloy powder. [ABSTRACT FROM AUTHOR]

Polycrystalline δ-phase Sc 4 Hf 3 O 12 was irradiated with light and heavy ions to study the radiation stability of this compound. In order to explore the ion species spectrum effect, the irradiations were performed with 400 keV Ne 2+ ions to fluences ranging from 1 × 10 14 to 1 × 10 15 ions/cm 2 , 600 keV Kr 3+ ions to fluences ranging from 5 × 10 14 to 5 × 10 15 ions/cm 2 , and 6 MeV Xe 26+ ions to fluences ranging from 2 × 10 13 to 1 × 10 15 ions/cm 2 . Irradiated samples were characterized by various techniques including grazing incidence X-ray diffraction (GIXRD) and transmission electron microscopy (TEM). A complete phase transformation from ordered rhombohedral to disordered fluorite was observed by a fluence of 1 × 10 15 ions/cm 2 with 400 keV Ne 2+ ions, equivalent to a peak ballistic damage dose of ∼0.33 displacements per atom (dpa). Meanwhile, the same transformation was also observed by 600 keV Kr 3+ ions at the same fluence of 1 × 10 15 ions/cm 2 , which however corresponds to a peak ballistic damage dose of ∼2.2 dpa. Only a partial O-D transformation was observed for 6 MeV Xe 26+ ions in the fluence range used. Experimental results indicated that the O-D transformation is observed under both electronic and nuclear stopping dominant irradiation regimes. It was also observed that light ions are more efficient than heavy ions in producing the retained defects that are presumably responsible for the O-D phase transformation. The O-D transformation mechanism is discussed in the context of anion oxygen Frenkel defects and cation antisite defects. We concluded that the irradiation induced O-D transformation is easier to occur in δ-phase compounds with partial order of cations than in that with fully disordered cation structures. [ABSTRACT FROM AUTHOR]

A novel material, amidoximated polyacrylonitrile/exfoliated Na-montmorillonite composite (Na-Mont–APAN) was synthesized and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), energy dispersive X-ray spectroscopy (EDS), CHN analysis, and potentiometric titration. The material was nonporous, amidoximated, montmorillonite-exfoliated and expected to be used for the recovery of uranyl from aqueous solutions. Effects of pH, contact time, temperature and background electrolyte on the adsorption were investigated. The results showed that the adsorption process strongly depended on pH and ionic strength, fitted well with Langmuir model and presented endothermic, spontaneous properties. The prepared material exhibited high adsorption capacity (736 mg/g at pH 4.0 and 318 K) and excellent selectivity for uranyl, indicating a potential application in the recovery/removal of uranyl from aqueous solutions. The binding mechanism of uranyl with Na-Mont–APAN was demonstrated with the help of FT-IR, XPS and R uranyl/AO . As a result, a dominant binding mode i.e. η 2 coordination was proposed. [ABSTRACT FROM AUTHOR]

Cu/Cr nanostructured multilayer films (NMFs) with modulation periods ( λ ) ranging from 250 nm to 10 nm and modulation ratios ( η ) ranging from 0.1 to 2.0 were prepared on flexible polyimide substrates by using magnetron sputtering. Upon uniaxial tensile testing, the critical cracking strain ( ε c ), critical buckling strain ( ε b ), and fracture toughness ( K IC ) of the NMFs were experimentally measured and all of the mechanical properties showed remarkable λ - and η -dependences. The cracking and buckling behaviors of the Cu/Cr NMFs were systematically investigated and both were found to depend strongly on the length scale. Based on an energy balance model, the interfacial adhesion energies ( Γ ) were determined using the measured buckle dimensions. Cracking maps and buckling maps were constructed from the experimental data to summarize the effects of λ and η on the cracking and buckling modes, respectively. In the cracking map, two regimes can be identified: one is brittle fracture with straight cracks and the other is ductile fracture with zigzag cracks. The ductile fracture regime is located in the region where λ ∼ 40 ± 20 nm and simultaneously η < ∼0.3, and the brittle-to-ductile transition is characterized by a fracture toughness criterion of K IC ∼ 12.5 MPa m 1/2 . In the buckling map, four regimes are distinguished: cracked rectangular buckles, uncracked rectangular buckles, cracked triangular buckles, and uncracked triangular buckles. The effects of the length-scale-dependent deformation and adhesion energies on the buckling behaviors were discussed. A combined dimensionless parameter of K IC / E f Γ ( E f : elastic modulus of the NMF) was proposed to assess the buckling behaviors, and the K IC / E f Γ contours coincided well with the boundaries dividing the four buckling regimes. [ABSTRACT FROM AUTHOR]

Long-term stability of devices based on organic materials is still impeding the diffusion of these structures in real applications. In this paper we have investigated the effects of low energy, combined, ion implantation (N and Ne) in the evolution of the electrical performances of pentacene-based Organic Thin Film Transistors (OTFTs) over time by means of current–voltage and photocurrent spectroscopy analyses. We have demonstrated that the selected combination of ions allows reducing the degradation of charge carriers mobility, and also stabilization of the devices threshold voltage over a long time (over 2000 h). [ABSTRACT FROM AUTHOR]

A Nd 3+ doped LaF 3 crystal has been grown by Czochralski method, and the X-ray diffraction results show that Nd 3+ have not changed the essential LaF 3 structure. Room temperature absorption spectrum, fluorescence spectrum and fluorescence decay curve of the crystal are measured and analyzed in detail. By applying the Judd–Ofelt approach, the emission probabilities, branching ratios and radiative lifetime for the transitions from 4 F 3/2 manifold are investigated. Furthermore, the emission cross-section for the transition of 4 F 3/2 → 4 I 11/2 as well as the fluorescence lifetime of 4 F 3/2 manifold are obtained and analyzed. The radiative lifetime, fluorescence lifetime and quantum efficiency are 567 μs, 522 μs and 92%, respectively. The results are compared with other Nd 3+ doped hosts, indicating that Nd:LaF 3 is favorable laser media. [ABSTRACT FROM AUTHOR]

Er-stuffed pyrochlore series Er 2 (Ti 2− x Er x )O 7− x /2 ( x = 0, 0.162, 0.286, 0.424 and 0.667) were synthesized using conventional ceramic processing procedures. The structure of Er 2 (Ti 2− x Er x )O 7− x /2 is effectively tailored by the Er stuffing level ( x ). In order to study the radiation effect of Er-stuffed pyrochlores, irradiation experiments were performed with 400 keV Ne 2+ ions to fluences ranging from 5 × 10 14 to 3.0 × 10 15 ions/cm 2 at cryogenic condition. Irradiation induced microstructural evolution was examined using a grazing incidence X-ray diffraction technique. It is found that the irradiated layer of Er 2 (Ti 2− x Er x )O 7− x /2 undergoes significant lattice disordering and swelling at fluences of ⩽1.5 × 10 15 ions/cm 2 and amorphization at fluences of ⩾1.5 × 10 15 ions/cm 2 . The radiation effect depends strongly on the chemical compositions of the samples. Both the lattice swelling percentage and the amorphous fraction decrease with increasing x . The experimental results are discussed in the context of cation antisite defect. The defect formation energy which varies as a function of x is responsible for the difference in the structural behaviors of Er 2 (Ti 2− x Er x )O 7− x /2 under 400 keV Ne 2+ ion irradiation. [ABSTRACT FROM AUTHOR]

Cr diffusion in trilayer thin films of 100 nm Fe–18Cr/125 nm TiO 2− x /100 nm Fe–18Cr deposited on MgO substrates at 500 °C was studied by either annealing at 500 °C or Ni 3+ ion irradiation at 500 °C. Microchemistry and microstructure evolution at the metal/oxide interfaces were investigated using (high-resolution) transmission electron microscopy, energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy. Diffusion of Cr into the O-deficient TiO 2 layer, with negligible segregation to the FeCr/TiO 2− x interface itself, was observed under both annealing and irradiation. Cr diffusion into TiO 2− x was enhanced in ion-irradiated samples as compared to annealed. Irradiation-induced voids and amorphization of TiO 2− x was also observed. The experimental results are rationalized using first-principles calculations that suggest an energetic preference for substituting Ti with Cr in sub-stoichiometric TiO 2 . The implications of these results on the irradiation stability of oxide-dispersed ferritic alloys are discussed. [ABSTRACT FROM AUTHOR]

In this work we investigated the formation and stability of intermetallics formed in a maraging steel PH 13-8 Mo under proton radiation up to 2 dpa utilizing nanoindentation, microcompression testing and atom probe tomography. A comprehensive discussion analyzing the findings utilizing rate theory is introduced, comparing the aging process to radiation induced diffusion. New findings of radiation induced segregation of undersize solute atoms (Si) towards the precipitates are considered. [ABSTRACT FROM AUTHOR]

Prior studies on He ion irradiation-induced damage in several immiscible metallic nanolayer systems with incoherent interfaces show a prominent size effect on mitigation of radiation damage frequently. In general, the magnitude of radiation hardening and defect cluster density are both lower in smaller individual layer thickness ( h ) than in larger h , as interfaces can effectively reduce the density of radiation-induced defect clusters. This research shows, however, an opposite size-dependent strengthening behavior in He ion-irradiated immiscible coherent Cu/Co multilayers, i.e. films with smaller h have greater radiation hardening. Such unusual size-dependent strengthening could be explained via a transition of strengthening mechanisms from partial dislocation (before radiation) to full dislocation transmission (after radiation) across layer interfaces as a result of the formation of He bubbles at the layer interfaces. Furthermore, it is shown that, similarly to incoherent immiscible systems, a coherent interface in the immiscible system can also effectively reduce the population of radiation-induced defect clusters. [ABSTRACT FROM AUTHOR]

Highly porous low-k dielectrics are essential for downscaling of the interconnects for 20–10 nm technologies. A planar capacitor test vehicle was used to investigate the intrinsic time dependent dielectric breakdown (TDDB) reliability of low-k dielectrics and the origin of an observed C – V hysteresis was studied. We hypothesize that the hysteresis is caused by donor-like traps present in the bulk of the low-k but not by electron/hole trapping or mobile charges. It is proposed that porogen/carbon residues are the source of these donor-like traps. Using I leak vs. time measurements, it was found that the donor-like traps accelerate the dielectric degradation due to an enhanced E OX , causing a localized partial breakdown. The intrinsic TDDB reliability of the low-k film was improved by adding a sealing layer as such layer blocked the donor-like traps discharging. [ABSTRACT FROM AUTHOR]

High-k dielectric stacks have been used in the 20 nm generation of floating gate (FG) flash memory cells. However, electron trapping in high-k materials remains a major concern for further development of FG technology. The hybrid FG (HFG) device with high-k inter-gate-dielectric (IGD) is a promising candidate with advantages of larger windows and less cell-to-cell interference, in which the poly floating gate is replaced by an n-poly/p-metal bi-layer structure. In this paper, to continue our previous work, the window instability in HFG with engineered IGD stacks during memory operations has been extensively studied. The results show that the HFG cell with the HAH (HaH) IGD structure provides not only the largest window but also the least instability, making it a suitable candidate beyond the 1× nm flash technology node. [ABSTRACT FROM AUTHOR]

Abstract: Large-scale production of strontium hexaferrite (SrFe12O19) particles was successfully achieved by molten-salt-assisted coprecipitation. A mixture of sodium hydroxide and sodium carbonate was served as mixed precipitant to obtain ferrite precursors. The effects of the Fe3+/Sr2+ molar ratio, calcination temperature, calcination time, and molten-salt amount on the formation, morphology and magnetic properties of SrFe12O19 particles were investigated. The resultant particles were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometer. Single-phase SrFe12O19 particles, with particle sizes of 0.8–1.2μm, were obtained from the precursor (with a Fe3+/Sr2+ molar ratio of 10) being calcined at 950°C for 2h using the mass ratio (NaCl to precursor) of 0.3. The saturation magnetization, remanent magnetization and coercivity were about 62emu/g, 37emu/g, and 4310Oe, respectively. A comparison of the products obtained at different preparation-scales was also done. The results showed that it was easier to control the particle morphology using molten salt synthesis and more economical on a large-scale production. [Copyright &y& Elsevier]

Abstract: Molecular dynamics (MD) simulations are performed to investigate how ∑3 (121) symmetric tilt grain boundary (GB) affects point defects and defect clusters in He-doped α-iron at 300K in picosecond time scales. Molecular statics calculations are also performed and show that the formation energy is reduced in the GB, and the GB acts as a good sink for point defects, especially for interstitial He and self-interstitial atoms (SIAs). It is observed that the average size of He n V m (m > n) clusters becomes smaller in the GB-containing Fe system, where m and n represent the number of vacancies and He atoms in the cluster, respectively. It is also found that the number of He n V (n =2, 3) clusters in the GB region decreases, while the number of the HeV clusters increases. The GBs loaded with substitutional or interstitial helium atoms are found to facilitate the growth of helium clusters in the GB region. [Copyright &y& Elsevier]

The 12Cr1MoWV (wt%) ferritic/martensitic steel HT9 is a candidate material for fuel cladding in advanced nuclear reactors, such as the Versatile Test Reactor currently under development. As such, understanding the relationship between microstructure and mechanical properties in the context of irradiation environments for these steels is critical. N content, and more specifically interstitial N, has been hypothesized to be detrimental to irradiated properties at lower temperatures (less than 0.3T m) to a total of 6 dpa; however, in this work at a dose of 1 dpa the irradiated microstructure was improved with added N, leading to less irradiation hardening. Three variants of HT9 were irradiated with 1.5 MeV protons to a dose of 1 dpa at 300 ˚C. The HT9 variants included Low (10 ppm), Mid (190 ppm), and High (440 ppm) N alloys that were otherwise nearly identical. Changing the N content had a variety of effects on the irradiated defect structures. As N content increased, the average dislocation loop diameter decreased, while the number density of loops increased. Additionally, extensive Ni clustering was observed on dislocations and interfaces. The Mid and High N specimens exhibited significantly less hardening (ΔHV ≅ 100) relative to the Low N specimen (Δ HV ≅ 160). The decrease in hardening is attributed to vanadium carbonitride acting as a sink for Ni clusters that would otherwise form on dislocations. Under the irradiation conditions used, these results suggest increasing the N content in HT9 may have a desirable effect on the irradiated structure and properties at the dose studied, as well as the swelling resistance at higher doses. In other words, N content appears to be a powerful tool for tailoring the self-interstitial atom cluster mobility in F/M steels for different temperature and dose applications. [ABSTRACT FROM AUTHOR]

• Fatigue behavior of Cu films on wrinkled PDMS substrates is investigated. • Wrinkled surfaces significantly enhance fatigue resistance of Cu films. • Buffering of wrinkle structures inhibit the crack initiation. • Surface undulations suppress the crack propagation. • Fatigue resistance exhibits film thickness and strain amplitude effects. The fatigue behavior of nanocrystalline Cu films on polydimethylsiloxane (PDMS) substrates was studied. It is revealed that the Cu films on wrinkled PDMS substrates exhibit ultrahigh fatigue resistance without electrical failure. The electrical resistance either remains constant during cyclic loading or slightly increases and rapidly reaches saturation, which is attributed to the buffering effect of wrinkle structures on crack initiation and the suppression effect of surface undulations on crack propagation. The film thickness-dependence of fatigue resistance is sensitive to the amount of the strain amplitude. The fatigue resistance increases with decreasing film thickness at small strain amplitudes because of higher strength and smaller local strain concentration, while the fatigue resistance first increases and then decreases as the film thickness increases at large strain amplitudes, which is related to the extrinsic deformation capability of Cu films. [ABSTRACT FROM AUTHOR]

In this work, a nanocrystalline (NC) Cu-10at.%Ta alloy is irradiated with helium at different temperatures to assess the stability and effectiveness of Ta nanoclusters in trapping helium and suppressing swelling. Advanced microstructural characterization of the room-temperature irradiated specimens indicated the presence of small He-bubbles (∼1-2 nm) at the peak damage depth mainly at the core and along the interface of Ta nanoclusters with Cu matrix. Few bubbles were found along grain boundaries, with much smaller bubbles homogenously distributed within the copper lattice. High-temperature irradiation exhibited bubbles of ∼3-5 nm, which were primarily associated with nanoclusters as compared to other locations, with no observed faceting of the bubbles. Atom probe analysis confirmed helium partitioning to the Ta nanoclusters indicating the effective entrapment of these He atoms. [Display omitted] [ABSTRACT FROM AUTHOR]

The deformation and failure behavior of a porous SiC/Ti-based metallic glass composite were investigated under uniaxial compression over a wide strain rate range (~10−5 to ~103 s−1). Both the metallic glass and the SiC phase exhibited a three-dimensional (3D) interconnected net structure. The composite showed positive strain rate sensitivity when the strain rate increased from ~10−5 to ~10−3 s−1 under quasi-static compression as well as from 1.7×103 to 3.4×103 s−1 under dynamic compression. However, the fracture strength of the composite during quasi-static compression was much greater than that during dynamic compression. The fracture mode of the composite was a mixture of shearing and axial splitting under both quasi-static and dynamic compressions; the main cracks initiated at the interface between the two phases or within the SiC phase. The SiC phase and the metallic glass phase were highly constrained by each other, leading to a complicated stress state in the composite. The composite failed earlier under dynamic compression due to the cracks being initiated and propagated more quickly in comparison with quasi-static compression. [ABSTRACT FROM AUTHOR]

Highlights: [•] The folic acid-conjugated Fe3O4 nanoparticles were synthesized by amidation method. [•] The conjugation of folic acid was verified qualitatively by UV–vis spectrum. [•] We confirmed the exothermic effect of the nanoparticles in alternating magnetic field. [•] The nanoparticles showed targeting effect to KB cells with FA receptors over-expression. [ABSTRACT FROM AUTHOR]

Highlights: [•] Novel stir casting assisted by ultrasonic treatment was developed. [•] Ultrasonic treatment significantly improved the stir casting. [•] Ultrasonic treatment improved the mechanical properties. [Copyright &y& Elsevier]

Highlights: [•] UC process and FE properties were first investigated in SBN:xEr3+ ceramics. [•] Bright UC green emission of SBN:xEr3+ system was first observed at room temperature. [•] Two-photon energy transfer process was confirmed for UC green and red emission. [•] Remarkably enhanced FE polarization of SBN:xEr3+ was reported for SBN:xEr3+. [ABSTRACT FROM AUTHOR]

Highlights: [•] Poly(St-AA)/Fe3O4 microspheres were prepared via miniemulsion copolymerization. [•] The effect of crosslinker on the final particle morphology was studied. [•] The adsorbed weight of BSA at different adsorption time and pH were investigated. [•] The adsorbed weight of BSA was increased with the content of AA. [Copyright &y& Elsevier]

Abstract: This study systematically investigates the interface structure of Nb films grown on MgO substrates with different orientations ((100) and (111)) by experiments and simulations. X-ray diffraction, transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) were used to characterize the structure of Nb films and the structure of interfaces between Nb films and MgO substrates. The results show that thin films exhibit different preferred planes on different orientations of MgO substrates. First-principles calculations were used to understand the interface configuration through a coherent interface model. The combination of experiments and simulations shows that the work of separation, together with substrate orientation and lattice mismatch, determines the interface structure between films and substrates. [Copyright &y& Elsevier]

To assist the development of applications for multilayer piezoelectric devices, the low-temperature sintering piezoelectric ceramics of 0.3Pb(Zn1/3Nb2/3)O3-0.7Pb(Zr0.49Ti0.51)O3 with Li2CO3 and Sm2O3 additives were fabricated by a conventional solid-state reaction, and their structural and piezoelectric properties were studied. With the addition of Li2CO3, the minimum sintering temperature of 0.3Pb(Zn1/3Nb2/3)O3-0.7Pb(Zr0.49Ti0.51)O3 piezoelectric ceramics was reduced from 1125°C to 950°C through the formation of a liquid phase and its piezoelectric properties showed almost no degradation. When the sintering temperature was below 950°C, however, the piezoelectric properties degraded obviously. The additional Sm2O3 resulted in a significant improvement in the piezoelectric properties of 0.3Pb(Zn1/3Nb2/3)O3-0.7Pb(Zr0.49Ti0.51)O3 ceramic with added Li2CO3. When sintered at 900°C, the optimized properties of the 0.3Pb(Zn1/3Nb2/3)O3-0.7Pb(Zr0.49Ti0.51)O3 piezoelectric ceramic with 0.3wt% Li2CO3 and 0.3wt% Sm2O3 were obtained as d 33 =483pC/N, k 31 =0.376, Q m =73, ɛ r =2524, tan δ =0.0178. [ABSTRACT FROM AUTHOR]

Abstract: Sm3+ ions doped Bi1/2Na1/2TiO3 (BNTO: xSm3+) polycrystalline samples with different Sm3+ concentrations were synthesized through the solid-state reaction method. Their microstructural, photoluminescence, and ferroelectric (FE) properties were investigated. Strong reddish-orange emission centered at 597nm has been successfully observed at room temperature. More importantly, the strong emission of BNTO: xSm3+ can be excited by both blue light and near ultraviolet radiation which indicates that BNTO: xSm3+ can act as a potential phosphor. Furthermore, the optimized photoluminescence is realized in BNTO: xSm3+ with x=0.02 sample which also shows relatively good ferroelectric properties. [Copyright &y& Elsevier]

Abstract: Radiation damage mechanisms in single crystal SrTiO3 irradiated with 250keV Ne ions to a fluence of 1.11×1020 ions/m2 at both room temperature and 773K were systematically investigated. The irradiation-induced microstructural evolution was characterized using transmission electron microscopy. Ion irradiation at room temperature results in amorphization of crystalline SrTiO3 near the peak damage region at this fluence. On the other hand, ion irradiation at high temperature leads to less irradiation-induced damage in SrTiO3 due to the higher recovery rate of defects. Nevertheless, the formation of dislocation loops has been observed in the SrTiO3 crystals irradiated at high temperature. These dislocation loops were determined to be unfaulted loops with Burgers vector along 〈011〉. [Copyright &y& Elsevier]

Abstract: Interface effects on ion-irradiation tolerance properties are investigated in nanolayered TiN/AlN films with individual layer thickness varied from 5nm to 50nm, prepared by pulsed laser deposition. Evolution of the microstructure and hardness of the multilayer films are examined on the specimens before and after He ion-implantation to a fluence of 4×1020 m−2 at 50keV. The suppression of amorphization in AlN layers and the reduction of radiation-induced softening are observed in all nanolayer films. A clear size-dependent radiation tolerance characteristic is observed in the nanolayer films, i.e., the samples with the optimum layer thickness from 10nm to 20nm show the best ion irradiation tolerance properties, and a critical layer thickness of more than 5nm is necessary to prevent severe intermixing. This study suggests that both the interface characteristics and the critical length scale (layer thickness) contribute to the reduction of the radiation-induced damages in nitride-based ceramic materials. [Copyright &y& Elsevier]

Abstract: We compare the evolution of microstructure and mechanical properties of Ag/Ni multilayers of varying layer thickness (1–200nm) subjected to helium ion and proton irradiation at room temperature to similar dose, ∼2 displacements-per-atom on average. Layer structure remained intact after both types of irradiation although defects accumulated in the layers are different. Helium bubbles were the major defects in helium ion irradiated films, while dislocation loops were ubiquitous in proton irradiated multilayers. In He ion irradiated multilayers, radiation hardening was greater than that in proton irradiated specimens, and the magnitude of hardening decreased with decreasing individual layer thickness. In comparison no size dependent hardening was observed in proton irradiated films. Mechanisms of irradiation induced hardening were discussed. [Copyright &y& Elsevier]

In this study, polycrystalline δ-phase Lu4Hf3O12 was irradiated with 6MeV Xe26+ ions to fluences ranging from 2×1013 to 1×1015 ions/cm2. Ion irradiation-induced microstructural evolution was examined by using grazing incidence X-ray diffraction (GIXRD). A complete phase transformation from ordered rhombohedral to disordered fluorite (O–D) was observed by a fluence of 1×1015 ions/cm2, equivalent to a peak ballistic damage dose of ∼3.49 displacements per atom (dpa). To research the different irradiation effect between light ion and heavy ion on δ-Lu4Hf3O12, 400keV Ne2+ ions were implanted to ion fluences ranging from 1×1014 to 1×1015 ions/cm2. A complete O–D crystal structure transformation was observed by a fluence of 5×1014 ions/cm2 (∼0.22dpa). This threshold dose was found to be observably lower than the threshold dose to produce order-to-disorder transformation using Xe26+ ions on δ-Lu4Hf3O12. This suggests that heavy ions are less efficient than light ions in producing the retained defects that are responsible for the O–D transformation. The theoretical calculations show that the O–D transformation of δ-phase was attributed to the anion oxygen Frenkel pair defect. The ion irradiation-induced transformation of δ-phase Lu4Hf3O12 into disordered fluorite structure observed here is also discussed in relation to the temperature–composition (T–C) phase diagrams for the compound. [ABSTRACT FROM AUTHOR]

• Stretchability of Cu films on wrinkled PDMS substrates is investigated. • Wrinkling structures significantly enhanced stretchability of Cu films. • Effect of film thickness and wrinkle size on fracture strain is reported. • Fracture strain evolves in a non-monotonic manner for smaller wrinkles. • Fracture strain monotonically increases for larger wrinkles. Stretchable electronics demand that the metal thin film electrodes have the capacity to experience large level of strains without obvious changes in electrical performance. This work investigated the effect of film thickness and wrinkle dimension on the stretchability of Cu films on polydimethylsiloxane substrates. It is revealed that the wrinkle dimension highly depends on the ultraviolet/ozone treatment time. The fracture strain increases until reaching a maximum and then decreases with increasing film thickness for smaller wrinkles. By contrast, the fracture strain monotonically increases as the film thickness increases for the larger wrinkles within the thickness range studied. Generally, the larger wrinkle dimension leads to a higher fracture strain for a given film thickness. The evolution of fracture strain can be rationalized in terms of the competition between the intrinsic stretchability of Cu films related to the grain size and the extrinsic strain concentration related to film thickness and wrinkle dimension. [ABSTRACT FROM AUTHOR]

The heavy-ion irradiation behavior of bulk zirconium-niobium multilayered composites was investigated up to large doses. Multilayers with an average individual layer thicknesses ranging between 15 and 80 nm were synthesized by accumulative roll bonding technique. The irradiation was performed with a defocused 7 MeV Zr2+ ion beam at 500 °C. The maximum dose achieved was ∼145 dpa at the depth of ∼1.5 μm from the irradiated surface. Sub-surface microstructural damage and the chemical redistribution were characterized by transmission electron microscopy and energy dispersive spectroscopy, respectively. Irrespective of the layer thicknesses, the irradiation condition caused layer instability and the extent of damage varied with the dose levels. Doses lesser than ∼60 dpa caused layer fragmentation and greater than ∼60 dpa resulted in layer dissolution. The chemical mixing of layers occur to a depth of ∼1 μm, consuming multiple bi-layer periods. Despite the elevated irradiation temperature (500 °C) and a slightly positive heat of mixing (+6 kJ/mol), no phase separation was observed and single-phase was retained in the mixed region. The results demonstrate that chemical mixing was facilitated by the liquid phase miscibility of Zr and Nb, which propelled the interdiffusion within the thermal spikes towards mixing. [ABSTRACT FROM AUTHOR]

The theory of singuarity functions is introduced to present an analytical approach for the natural properties of a unidirectional vibrating steel strip with two opposite edges simply supported and other two free, partially submerged in fluid and under tension. The velocity potential and Bernoulli's equation are used to describe the fluid pressure acting on the steel strip. The effect of fluid on vibrations of the strip may be equivalent to added mass of the strip. The math formula of added mass can be obtained from kinematic boundary conditions of the strip-fluid interfaces. Singularity functions are adopted to solve problems of the strip with discontinuous characteristics. By applying Laplace transforms, analytical solutions for inherent properties of the vibrating steel strip in contact with fluid are finally acquired. An example is given to illustrate that the proposed method matches the numerical solution using the finite element method (FEM) very closely. The results show that fluid has strong effect on natural frequencies and mode shapes of vibrating steel strips partially dipped into a liquid. The influences such as tension, the submergence depth, the position of strip in the container and the dimension of the container on the dynamic behavior of the strip are also investigated. Moreover, the presented method can also be used to study vertical or angled plates with discontinuous characteristics as well as different types of pressure fields around. [ABSTRACT FROM AUTHOR]

Abstract: Aligned gallium nitride (GaN) nanowires were catalytically synthesized in a plasma-enhanced hot filament chemical vapor deposition system, in which GaN powder and nitrogen were used for the gallium and nitrogen sources, respectively. The results of scanning electron microscope, X-ray diffractometer, micro-Raman spectroscopy and transmission electron microscope indicate that the n-type GaN nanowires with different diameters are formed in wurtzite crystal structure. Combined the vapor–liquid–solid growth mechanism with the plasma-related effects, the formation of n-type GaN nanowires with different diameters was analyzed. The electrical property of a single GaN nanowire was measured in transmission electron microscope at room temperature and the result indicates that the current–voltage curve exhibits a nonlinear behavior and a double diode-like characteristic. In particular, the double diode-like characteristic is highly related to the application of GaN nanowires in the area of nano-diode devices such as alternating current limiter. [Copyright &y& Elsevier]

Abstract: The accumulation of radiation-induced defect clusters and He bubble formation in He+ ion irradiated nanocrystalline TiO2 and Fe–TiO2 multilayer thin films were investigated using transmission electron microscopy (TEM). Prior to ion irradiation it was found that the crystallinity of TiO2 layers depends on the individual layer thickness: While all TiO2 layers are amorphous at 5nm individual layer thickness, at 100nm they are crystalline with a rutile polymorph. After He+ irradiation up to ∼6dpa at room temperature, amorphization of TiO2 layers was not observed in both nanocrystalline TiO2 single layers and Fe–TiO2 multilayers. The suppression of radiation-induced amorphization in TiO2 is interpreted in terms of a high density of defect sinks in these nano-composites in the form of Fe–TiO2 interphase boundaries and columnar grains within each layer with nano-scale intercolumnar porosity. In addition, a high concentration of He is believed to be trapped at these interfaces in the form of sub-nanometer-scale clusters retarding the formation of relatively larger He bubbles that can be resolved in TEM. [Copyright &y& Elsevier]

Abstract: Manufacturing of microstructured mold surfaces was realized by the micromachining of thick sol–gel silica hybrid coatings. The films were deposited onto pre-machined steel molds by spin coating using NaOH-catalyzed sols from organosilicate precursors. The effect of the sol synthesis and the heat treatment on the mechanical and chemical properties of these films was studied in order to develop thick and crack-free films with appropriate properties for micromachining with diamond cutting tools. The hardness was measured by nanoindentation as a function of the heat treatment temperature. The transition from soft organic gel films to hard glass-like films due to the thermal treatment was characterized by X-ray photoelectron spectroscopy, elastic recoil detection, and Raman and infrared spectroscopies. The films from NaOH catalyzed sols showed a complex transition from aliphatic carbon originating from hydrocarbon groups to carbonates, carboxylates and disordered carbon clusters. [Copyright &y& Elsevier]

We have explored the capacity of Cu/V interfaces to absorb helium ion radiation-induced defects spanning a peak damage range of 0.6–18 displacements per atom (dpa). The study provides evidence of alleviated nucleation of He bubbles in the multilayer films from Cu/V 50 nm to Cu/V 2.5  nm. Layer interfaces are retained in all irradiated specimens. Peak bubble density increases monotonically with fluence, and is lower in multilayers with smaller individual layer thickness. Radiation hardening decreases with decreasing layer thickness and appears to reach saturation upon peak radiation damage of 6 dpa. Size- and fluence-dependent radiation damage in multilayers is discussed. [ABSTRACT FROM AUTHOR]

Abstract: This paper is a continuation of the paper titled “Fatigue assessment of a composite railway bridge for high speed trains-Part I: modeling and fatigue critical details” with the emphasis on conditions for which a dynamic analysis is needed for a fatigue assessment of the bridge. In part I, a fatigue assessment of the Sesia viaduct is performed by using both a static analysis and a dynamic analysis with a moving load model; fatigue damage levels of several concerned details are calculated and the fatigue critical details are identified. It is found that dynamic effects induced by the high speed trains reveal a big influence on the fatigue damage of the bridge. In this paper, conditions under which a dynamic analysis should be considered for the fatigue assessment of a bridge are investigated. Three different alternatives are considered: a static analysis taken into account a dynamic amplification factor, a dynamic analysis with a moving load model, or a dynamic analysis with multi-body models for the train vehicles include the train–bridge interaction effect. The effect of several parameters related to the train and the bridge is studied. The train speed and the mass ratio between the train and the bridge are identified as significant factors that determine the dynamic effect on the fatigue damage of the bridge. [Copyright &y& Elsevier]

Abstract: Steel bridges for high speed trains may sustain excessive fatigue damage due to stronger dynamic effects induced by the increased train speed. Dynamic tests were carried out on a composite railway bridge for high speed trains. A detailed finite element (FE) model of the bridge was established and validated by the dynamic test results. Six types of structural details in the bridge were considered for fatigue evaluation. The stress history of each concerned detail during a single train passage was generated by the validated FE model. The stress spectrum, obtained through Rainflow cycle counting of stress history, was used to calculate the fatigue damage of each detail, based on the detail category specified S–N design curve and the Palmgren–Miner damage rule. Among various structural details, the load carrying fillet weld around the gusset plate of the diagonal bracing at the bridge bearing is predicted to be the most fatigue critical detail. In this paper, a general methodology for determination of fatigue critical details is presented, which can serve as a basis of enhanced fatigue evaluation by using local stress approaches. In “Part II: conditions for which a dynamic analysis is needed” as the continuation of this paper, fatigue assessment will be investigated based on the dynamic stresses predicted by different approaches, i.e. static analysis considering dynamic amplification factor, direct dynamic analysis with a moving load model or a train–bridge interaction model. [Copyright &y& Elsevier]

Abstract: A novel environmentally-friendly composite coating with a cerium conversion coating deposited on the phytic acid conversion sample was formed on an AZ31B magnesium alloy. The optimum processing parameters of the composite coating on the AZ31B magnesium alloy were investigated by hydrogen evolution method. The surface morphology, chemical nature and corrosion resistance of the composite coating were examined by SEM, EDS, FTIR, XRD, electrochemical measurements and hydrogen evolution method. The results show that the optimum processing parameters of the composite coating on the AZ31B magnesium alloy are cerium nitrate solution concentration of 0.06mol/L, treating time of 30min and treating temperature of 50°C. The composite coating has better uniformity than the phytic acid conversion coating and it is composed of O, C, P, Mg, Al and Ce. The P–OH, HPO4 2−, PO4 3−, CeO2 and a little Ce(OH)2 exist in the surface of the composite coating and the composite sample has best corrosion resistance than the untreated sample, chromate conversion sample and phytic acid conversion sample. The synergistic mechanism was also discussed. [Copyright &y& Elsevier]

Abstract: The dependence of the width of void-denuded zones (VDZs) on grain boundary (GB) characters was investigated in Cu irradiated with He ions at elevated temperature. Dislocation loops and voids formed near GBs during irradiation were characterized by transmission electron microscopy, and GB misorientations and normal planes were determined by electron back-scatter diffraction. The VDZ widths at Σ3〈110〉 tilt GBs ranged from 0 to 24nm and increased with the GB plane inclination angle. For non-Σ3 GBs, VDZ widths ranged from 40 to 70nm and generally increased with misorientation angle. Nevertheless, there is considerable scatter about this general trend, indicating that the remaining crystallographic parameters also play a role in determining the sink efficiencies of these GBs. In addition, the VDZ widths at two sides of a GB show different values for certain asymmetrical GBs. Voids were also observed within GB planes and their density and radius also appeared to depend on GB character. We conclude that GB sink efficiencies depend on the overall GB character, including both misorientation and GB plane orientation. [Copyright &y& Elsevier]

Abstract: Epitaxial anatase films with thickness of around 300nm were deposited on and irradiated with 250keV Ne ions at room temperature. X-ray diffraction, Rutherford backscattering spectrometry, and transmission electron microscopy were used to characterize the microstructural changes under irradiation. Two primary features are observed in the irradiated material: a damaged layer with a high density of nano-sized defects including dislocation loops was observed in the film and, near the interface, a defect denuded zone formed on the side while an amorphous layer formed on the side. Atomistic calculations attribute the formation of both the defect-denuded zone and the interfacial amorphous layer not to the interaction between the irradiation induced defects and the hetero-interface but rather differences in chemical potential and mobilities for defects in each of the two phases. [Copyright &y& Elsevier]

Abstract: SiCp/Mg–Zn–Ca composite fabricated by stir casting was extruded at three different temperatures. Firstly, hot extrusion significantly improved particle distribution and refined the grains of the matrix. Even, nano-grains were observed in the composite extruded at 250°C. Secondly, extrusion evidently refined the size of the second phases, but also changed the distribution of the second phases. Extrusion temperatures obviously affected the size and distribution of the second phases. Thirdly, the interface between SiCp and matrix was also modified by hot extrusion. Finally, all as-extruded composites possessed good mechanical properties. Below 150°C, the UTS was very high in the extruded composites, but their strengths decreased sharply above 150°C. [Copyright &y& Elsevier]