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<jats:p>The mechanical property and deformation mechanism of twinned gold nanowire with non-uniform distribution of twinned boundaries (TBs) are studied by the molecular dynamics (MD) method. It is found that the twin boundary spacing (TBS) has a great effect on the strength and plasticity of the nanowires with uniform distribution of TBs. And the strength enhances with the decrease of TBS, while its plasticity declines. For the nanowires with non-uniform distribution of TBs, the differences in distribution among different TBSs have little effect on the Young’s modulus or strength, and the compromise in strength appears. But the differences have a remarkable effect on the plasticity of twinned gold nanowire. The twinned gold nanowire with higher local symmetry ratio has better plasticity. The initial dislocations always form in the largest TBS and the fracture always appears at or near the twin boundaries adjacent to the smallest TBS. Some simulation results are consistent with the experimental results.</jats:p>

<jats:p>Methanol fuel cells have been intensively developed as clean and high-efficiency energy conversion system due to their high efficiency and low emission of pollutants. Here, we developed a simple aqueous synthetic method to prepare bimetallic PdAu nanoflowers catalysts for methanol oxidation reaction (MOR) in alkaline environment. Their composition can be directly tuned by changing the ratio between Pd and Au precursors. Compared with commercial Pd/C catalyst, all of the PdAu nanoflowers catalysts show the enhanced catalytic activity and durability. In particular, the PdAu nanoflowers specific activity reached 0.72 mA/cm<jats:sup>2</jats:sup>, which is 14 times that of commercial Pd/C catalyst. The superior MOR activity could be attributed to the unique porous structure and the shift of the d-band center of Pd.</jats:p>

<jats:p>We show the structural and optical properties of non-polar <jats:italic>a</jats:italic>-plane GaN epitaxial films modified by Si ion implantation. Upon gradually raising Si fluences from 5 × 10<jats:sup>13</jats:sup> cm<jats:sup>−2</jats:sup> to 5 × 10<jats:sup>15</jats:sup> cm<jats:sup>−2</jats:sup>, the n-type dopant concentration gradually increases from 4.6 × 10<jats:sup>18</jats:sup> cm<jats:sup>−2</jats:sup> to 4.5 × 10<jats:sup>20</jats:sup> cm<jats:sup>−2</jats:sup>, while the generated vacancy density accordingly raises from 3.7 × 10<jats:sup>13</jats:sup> cm<jats:sup>−2</jats:sup> to 3.8 × 10<jats:sup>15</jats:sup> cm<jats:sup>−2</jats:sup>. Moreover, despite that the implantation enhances structural disorder, the epitaxial structure of the implanted region is still well preserved which is confirmed by Rutherford backscattering channeling spectrometry measurements. The monotonical uniaxial lattice expansion along the <jats:italic>a</jats:italic> direction (out-of-plane direction) is observed as a function of fluences till 1 × 10<jats:sup>15</jats:sup> cm<jats:sup>−2</jats:sup>, which ceases at the overdose of 5 × 10<jats:sup>15</jats:sup> cm<jats:sup>−2</jats:sup> due to the partial amorphization in the surface region. Upon raising irradiation dose, a yellow emission in the as-grown sample is gradually quenched, probably due to the irradiation-induced generation of non-radiative recombination centers.</jats:p>

<jats:p>The relationship between ions irradiation and the induced microstructures (point defects, dislocations, clusters, <jats:italic>etc</jats:italic>.) could be better analyzed and explained by simulation. The mean field rate theory and cluster dynamics are used to simulate the effect of implanted Fe on the point defects concentration quantitatively. It is found that the depth distribution of point defect concentration is relatively gentle than that of damage calculated by SRIM software. Specifically, the damage rate and point defect concentration increase by 1.5 times and 0.6 times from depth of 120 nm to 825 nm, respectively. With the consideration of implanted Fe ions, which effectively act as interstitial atoms at the depth of high ion implantation rate, the vacancy concentration <jats:italic>C</jats:italic> <jats:sub>v</jats:sub> decreases significantly after reaching the peak value, while the interstitial atom concentration <jats:italic>C</jats:italic> <jats:sub>i</jats:sub> increases significantly after decline of the previous stage. At the peak depth of ion implantation, <jats:italic>C</jats:italic> <jats:sub>v</jats:sub> dropped by 86%, and <jats:italic>C</jats:italic> <jats:sub>i</jats:sub> increased by 6.2 times. Therefore, the implanted ions should be considered into the point defects concentration under high dose of heavy ion irradiation, which may help predict the concentration distribution of defect clusters, further analyzing the evolution behavior of solute precipitation.</jats:p>

<jats:p>Lattice defects induced by ion implantation into SiC have been widely investigated in the decades by various techniques. One of the non-destructive techniques suitable to study the lattice defects in SiC is the optical characterization. In this work, confocal Raman scattering spectroscopy and photoluminescence spectrum have been used to study the effects of 134-keV <jats:inline-formula> <jats:tex-math> <?CDATA ${{\rm{H}}}_{2}^{+}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi mathvariant="normal">H</mml:mi> <mml:mn>2</mml:mn> <mml:mo>+</mml:mo> </mml:msubsup> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_30_5_056106_ieqn3.gif" xlink:type="simple" /> </jats:inline-formula> implantation and thermal treatment in the microstructure of 6H-SiC single crystal. The radiation-induced changes in the microstructure were assessed by integrating Raman-scattering peaks intensity and considering the asymmetry of Raman-scattering peaks. The integrated intensities of Raman scattering spectroscopy and photoluminescence spectrum decrease with increasing the fluence. The recovery of the optical intensities depends on the combination of the implantation temperature and the annealing temperature with the thermal treatment from 700 °C to 1100 °C. The different characterizations of Raman scattering spectroscopy and photoluminescence spectrum are compared and discussed in this study.</jats:p>

<jats:p>SIMP steel is newly developed fully martensitic steel for lead-cooled fast reactors and accelerator-driven systems. It is important to evaluate its radiation resistance via high flux neutron irradiation, where dense He atoms can be formed via (n, <jats:italic>α</jats:italic>) transmutation reaction. Co-irradiation with Fe and He ions, instead of neutron, was performed. Specimens were irradiated with 6.4-MeV Fe ions to the damage dose of 5 dpa at a depth of 600 nm. Three different helium injection ratios of 60-appm He/dpa (dpa: displacements per atom), 200-appm He/dpa and 600-appm He/dpa at a depth of 600 nm, were performed. Two different irradiation temperatures of 300 °C and 450 °C were carried out. The effect of helium concentration on the microstructure of Fe-irradiated SIMP steel was investigated. Microstructural damage was observed using transmission electron microscopy. The formed dislocation loops and bubbles depended on the helium injection ratio and irradiation temperature. Lots of dislocation loops and helium bubbles were homogeneously distributed at 300 °C, but not at 450 °C. The causes of observed effects are discussed.</jats:p>

<jats:p>The GH3535 alloy samples were irradiated using 15-MeV Te<jats:sup>4+</jats:sup> ions at 650 °C to a dose of 0.5, 3.0, 10, and 20 dpa, respectively. The Te atoms distribution and microstructure evolution were examined by electron probe microanalysis (EPMA) and transmission electron microscopy (TEM). The nano-indenter was then used to measure the nano-hardness changes of samples before and after irradiation. TEM results showed the formation of dislocation loops in the irradiated samples. Their mean diameters increase with the increase of irradiation dose and tends to be saturated when irradiation dose exceeds 10 dpa. The ratio of yield strength increments calculated by dispersed barrier hardening (DBH) model is basically consistent with that of nano-hardness increments measured by nano-indenter. In addition, the relationship between the nano-hardness increments and dpa for the GH3535 alloy irradiated by Te ions has been revealed in the study.</jats:p>

<jats:p>Titanium and titanium–palladium alloys are important potential materials for nuclear waste container, which will endure both intense <jats:italic>γ</jats:italic>-irradiation and groundwater erosion. Therefore, it is very important to investigate the corrosion behavior of the container materials. In this research, the cumulative dose effect of TA8-1 type titanium–palladium alloy (TA8-1) and TA2-type pure titanium (TA2) under <jats:italic>γ</jats:italic>-irradiation was studied based on the geological disposal of nuclear wastes. The irradiation experiments were performed at room temperature using <jats:sup>60</jats:sup>Co gamma sources with a 5.0-kGy⋅h<jats:sup>−1</jats:sup> intensity for 40, 80 or 160 days, respectively. The pH value and conductivity of Beishan groundwater were investigated. The results showed that the pH value changed from alkaline (8.22) to acidic (2.46 for TA8-1 and 2.44 for TA2), while the un-irradiated solution remained alkaline (8.17 for TA8-1 and 8.20 for TA2) after 160 days. With the increase of irradiation dose, the conductivity increases rapidly and then tends to become stable, which indicates that the titanium dioxide corrosion layer formed on the surface of the sample surface effectively prevents further corrosion. Meanwhile, XRD and SEM–EDS analysis results show that the main components of corrosion products are TiO<jats:sub>2</jats:sub> and TiO. The titanium on the surface of the sample is oxidized, resulting in slight uneven local corrosion. The results show that TA8-1 and TA2 are suitable to be used as candidate materials for high-level waste (HLW) disposal containers due to their excellent performance under long-term and high-dose irradiation corrosion.</jats:p>

<jats:p>The electrical characteristics and microstructures of <jats:italic>β</jats:italic>-Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> Schottky barrier diode (SBD) devices irradiated with swift heavy ions (2096 MeV Ta ions) have been studied. It was found that <jats:italic>β</jats:italic>-Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> SBD devices showed the reliability degradation after irradiation, including turn-on voltage <jats:italic>V</jats:italic> <jats:sub>on</jats:sub>, on-resistance <jats:italic>R</jats:italic> <jats:sub>on</jats:sub>, ideality factor <jats:italic>n</jats:italic>, and the reverse leakage current density <jats:italic>J</jats:italic> <jats:sub>r</jats:sub>. In addition, the carrier concentration of the drift layer was decreased significantly and the calculated carrier removal rates were 5 × 10<jats:sup>6</jats:sup>–1.3 × 10<jats:sup>7</jats:sup> cm<jats:sup>−1</jats:sup>. Latent tracks induced by swift heavy ions were observed visually in the whole <jats:italic>β</jats:italic>-Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> matrix. Furthermore, crystal structure of tracks was amorphized completely. The latent tracks induced by Ta ions bombardments were found to be the reason for the decrease in carrier mobility and carrier concentration. Eventually, these defects caused the degradation of electrical characteristics of the devices. In terms of the carrier removal rates, the <jats:italic>β</jats:italic>-Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> SBD devices were more sensitive to swift heavy ions irradiation than SiC and GaN devices.</jats:p>

<jats:p>Concentrated solid-solution alloys (CSAs) have demonstrated promising irradiation resistance depending on their compositions. Under irradiation, various defects can be produced. One of the most important parameters characterizing the defect production and the resulting defect number is the threshold displacement energies (<jats:italic>E</jats:italic> <jats:sub>d</jats:sub>). In this work, we report the results of <jats:italic>E</jats:italic> <jats:sub>d</jats:sub> values in a series of Ni–Fe–Cr concentrated solid solution alloys through molecular dynamics (MD) simulations. Based on several different empirical potentials, we show that the differences in the <jats:italic>E</jats:italic> <jats:sub>d</jats:sub> values and its angular dependence are mainly due to the stiffness of the potential in the intermediate regime. The influences of different alloying elements and temperatures on <jats:italic>E</jats:italic> <jats:sub>d</jats:sub> values in different CSAs are further evaluated by calculating the defect production probabilities. Our results suggest a limited influence of alloying elements and temperature on <jats:italic>E</jats:italic> <jats:sub>d</jats:sub> values in concentrated alloys. Finally, we discuss the relationship between the primary damage and <jats:italic>E</jats:italic> <jats:sub>d</jats:sub> values in different alloys. Overall, this work presents a thorough study on the <jats:italic>E</jats:italic> <jats:sub>d</jats:sub> values in concentrated alloys, including the influence of empirical potentials, their angular dependence, temperature dependence, and effects on primary defect production.</jats:p>