Search

Scanning transmission electron microscopy (STEM) and X-ray photoelectron spectroscopy analyses were combined to clarify the ultraviolet light-induced surface changes of WO3 in air. Identical-location STEM (IL-STEM) analysis showed that the WO3 particle surface was covered with an amorphous thin film after ultraviolet irradiation in air. X-ray photoelectron spectroscopy analysis showed that hydrocarbon decomposition and the formation of carboxyl/hydroxyl species occurred. These results suggested that the amorphous thin films consisted of photocatalytic oxidative species of hydrocarbon. The IL-STEM analysis could detect small light-induced changes. This technique will be useful for the microscopic characterization of photocatalysis or photoinduced hydrophilic conversion. [ABSTRACT FROM AUTHOR]

Beryllium (Be) intermetallic compounds (beryllides) are promising materials for neutron multiplication in fusion reactors. In particular, titanium beryllide (Be12Ti) exhibits low swelling and good corrosion resistance compared to other beryllides. Herein, the defects in neutron‐irradiated Be12Ti are investigated using positron annihilation spectroscopy, and the results are analyzed based on positron annihilation calculations. Calculation results indicate that the positron lifetime in a perfect Be12Ti crystal is 134.2 ps, while that of a Be monovacancy is found to be within the 177.3–195.0 ps range, depending on the configuration of the monovacancy. On the other hand, the positron lifetime of the Ti monovacancy is 222.7 ps. In addition, the lifetimes of the Be and Ti vacancy clusters increase with an increase in the number of vacancies. Finally, the positron lifetimes of the antisite defects in different configurations are found to be within the 137.9–141.7 ps range. In contrast to the calculated results, the positron lifetime of unirradiated Be12Ti is 141.1 ps. Furthermore, in the neutron‐irradiated Be12Ti, no vacancies are detected and only Be dislocation loop formation occur based on the calculation results. Although the irradiation dose of Be12Ti is low, its irradiation resistance is satisfactory. [ABSTRACT FROM AUTHOR]

Various defects and amorphous transitions are the primary mechanism behind the accumulation of swelling in silicon carbide (SiC). In this study, selected-area He+ ion irradiation was carried out on single-crystal 4H-SiC using fluences of 1 × 1015, 5 × 1016, and 1 × 1017 cm−2 at room temperature. The defect distribution in the samples with varying irradiation fluences was analyzed using transmission electron microscopy (TEM), while the local swelling of regions under varying damage conditions was estimated using electron energy-loss spectroscopy. The results provide the range of swelling in SiC possessing different primary defect types, such as point defects or tiny clusters, black spot defects, and amorphous SiC. A saturation swelling with a value of 2%–3% in the near-surface region, induced by point defects or tiny clusters (invisible in TEM), was observed at room temperature over the fluence range of 1 × 1015 to 1 × 1017 cm−2. This saturation has already reached at a great low dose of about 0.02 dpa. The swelling of the region containing black spot defects ranges from about 3% to 7%. Helium bubbles increase the volume swelling of SiC, while the He+ ion irradiation may also perform a decreasing effect on the volume swelling below a certain irradiation fluence. [ABSTRACT FROM AUTHOR]

A complementary solid-state nuclear magnetic resonance and transmission electron microscopy (TEM) analysis was performed for LiBH4–ZrO2 nanocomposites. As a result, amorphous LiBH4 films with thicknesses of less than 30 nm were observed covering the ZrO2 particles. Li imaging by energy-filtered TEM is useful for the real-space characterization of nanoscale LiBH4. [ABSTRACT FROM AUTHOR]