[en] TiO₂ films with potential for dye-sensitized solar cells were deposited by using reactive medium frequency magnetron sputtering deposition. Two groups of films were prepared respectively by changing the oblique angle of the substrate and the total pressure. Scanning electron microscopy and spectroscopic ellipsometry measurements were used to characterize the deposited TiO₂ films. The result showed that increasing the oblique angle and increasing the total pressure were both effective in increasing the porosity of the TiO₂ films.

[en] The detection efficiency of thermal neutron and deposited energy spectrum for various structures of three-dimensional square pore silicon detector with ⁶LiF used as a neutron conversion material were simulated with Geant4 program based on Monte-Carlo method. The influence of pore parameter on detection efficiency was studied in detail. The pore size, pore space, pore depth and the lowest limit of detection (LLD) were employed to discuss the change of detection efficiency of thermal neutron. The results show that the detection efficiency increases at first and then decreases with increase of pore size or pore space, while it increases constantly to an extreme with pore depth. When the LLD is 300 keV, the detection efficiency of three-dimensional square pore silicon detector with pore space more than 6 μm is less affected by LLD. In theory, the three-dimensional square pore silicon detector with pore space of 6 μm, pore size of 30 μm and pore depth of 1 mm achieves the highest detection efficiency of 59.5%. (authors)

[en] Oxygen vacancy and interstitial diffusion mechanisms in uranium dioxide doped with zirconium are investigated by the density functional theory calculations. The migration pathways and barriers are identified using the climbing-image nudge elastic band (CI-NEB) method. It is found that the vacancy migration barrier along the <100> direction decreases by about 0.40 eV, while the indirect interstitial migration barrier decreases by about 0.07 eV in the zirconium doped uranium dioxide. The oxygen vacancy migration barrier is far lower than the oxygen interstitial migration barrier in the uranium dioxide doped with zirconium. Based on the analysis of bond length of local structures during the migration of oxygen atoms, it is concluded that the lattice distortion may be responsible for the reduction of oxygen migration barrier. (authors)

[en] Silicon macropore arrays were prepared by electrochemical etching in the solution of HF+IPA (isopropanol) and HF+IPA+CATC (cetyltrimethylammonium chloride). The effects of HF concentration, CTAC, etching current, etching time on the array morphologies were discussed. The optimized macropore array was obtained when the volume ratio of 40% HF, H_2O,IPA is 7:4:29. The pore wall is decreased with increasing the etching current and the initial etching expands in the direction of pore diameter until the pore diameter of about 10 μm. Regular arrays are not formed on the silicon with etching windows of 8 μm and spacing of 5 μm. Small pores are formed on macropore walls when CTAC is added in the solution. The small pores become smaller and the number of them is increased with increasing CTAC. (authors)