In this paper, we developed a new safe and facile route to prepare black titania at room temperature for visible light photocatalysis. The commercial Degussa P25 was used as the starting material, and it was hydrogenated at 35 bar hydrogen and room temperature for up to 20 days. The resulting hydrogenated P25 was characterized by XRD, FT-IR, Raman, UV-Vis, TEM and photocatalysis tests under visible light in methanol solution. It was found that P25 powders under hydrogen treated for more than 15 days have a dark appearance, a crystalline-disordered core-shell structure, unique phase structure and good photocatalytic performance. The H 2 evolution rates are 3.14, 3.56 and 3.94 mmol g À1 h À1 in 20% methanol solution for hydrogen treated P25 at 15, 17 and 20 days, respectively, which were largely higher than that with hydrogen treatment time less than 11 days. This work will provide a practical, green and facile method for the large scale synthesis of black titania at room temperature.

CeO2 layers epitaxially grown on (100) silicon substrates by electron-beam evaporation were investigated and proved to have (110) orientation. X-ray diffraction measurements showed the CeO2 layers consist of more than 98% volume fraction of the (110) component. Cross-sectional high-resolution transmission electron microscopy and selected-area electron diffraction clearly verified the above configuration of crystallographic orientations and that the 〈100〉 direction in the CeO2(110) plane is parallel with the 〈110〉 direction in the Si(100) plane. The cross-sectional lattice image clarified the existence of a ∼60-Å-thick intermediate amorphous layer between the CeO2 layer and the silicon substrate. Moreover, the high density of defects such as dislocations and low-angle boundaries that exist in the vicinity of the interface agree well with Rutherford backscattering and channeling measurements.

We have grown a-axis oriented YBa2Cu3O7−x (YBCO) thin films on Si(100) substrates with (110) oriented insulating buffer layers of cerium dioxide (CeO2) using the pulsed laser deposition technique. The films are highly oriented and textured as determined by θ–2θ x-ray diffraction, x-ray pole-figure scan, scanning electron microscopy, Rutherford backscattering spectroscopy, and ion channeling. No diffusion at the interface has been found at growth temperatures up to 760 °C, indicating the CeO2 is a chemically stable and structurally compatible intermediate material for the growth of YBCO on Si. A zero resistance superconducting transition temperature of 87 K and a critical-current density (Jc) of 1.5×105 A/cm2 at 75 K have been measured; Jc obtained represents the highest value for the a-axis oriented YBCO films.

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Ferroelectrics have recently attracted attention as a candidate class of materials for use in photovoltaic devices due to their abnormal photovoltaic effect. However, the current reported efficiency is still low. Hence, it is urgent to develop narrow-band gap ferroelectric materials with strong ferroelectricity by low-temperature synthesis. In this paper, the perovskite bismuth ferrite BiFeO3 (BFO) thin films were fabricated on SnO2: F (FTO) substrates by the sol–gel method and they were rapidly annealed at 450, 500 and 550 °C, respectively. The microstructure and the chemical state’s evolution with annealing temperature were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), and the relationship between the microstructure and electric, optical and photovoltaic properties were studied. The XRD, SEM and Raman results show that a pure phase BFO film with good crystallinity is obtained at a low annealing temperature of 450 °C. As the annealing temperature increases, the film becomes more uniform and has an improved crystallinity. The XPS results show that the Fe3+/Fe2+ ratio increases and the ratio of oxygen vacancies/lattice oxygen decreases with increasing annealing temperature, which results in the leakage current gradually being reduced. The band gap is reduced from 2.68 to 2.51 eV due to better crystallinity. An enhanced photovoltaic effect is observed in a 550 °C annealed BFO film with a short circuit current of 4.58 mA/cm2 and an open circuit voltage of 0.15 V, respectively.

The in situ excimer-laser deposition process is demonstrated, for the first time, to be an effective technique for producing superconducting films on both sides of substrate wafers of up to 5 cm in diameter. By exploiting the directed nature of the laser produced plume and controlling its off-axis composition, thickness and stoichiometric variations of less than ±5% have been obtained over the entire surface. Coatings on 5-cm-diam LaAlO3 substrates have uniform transition temperatures of ≥ (R18)90 K on both sides, with a critical current density at 77 K and zero field of 2.5×106 A/cm2. The 10 GHz surface resistance for samples cut from a 5 cm wafer is 40–60 μΩ at 4 K.

The in-plane, orientational relationships between LaAlO3, SrTiO3, yttria-stabilized zirconia, MgO, CeO2, BaZrO3, and YBa2Cu3O7−δ(YBCO) are studied. Using a idea of continuous lattice match and photolithographic technique, a 45° YBCO grain-boundary junction can be created on most substrates. The key element of the process is the utilization of a bridge layer. In addition to MgO bridge material, BaZrO3 was found to work functionally well. The crystallinity of the bridge layer is critical to obtain a clean boundary junction.

Successful doping of Eu3+ ions into ZnO nanocrystals has been realized by using a low temperature wet chemical doping technique. The substitution of Eu3+ for Zn2+ is shown to be dominant in the Eu-doped ZnO nanocrystals by analyzing the X-ray diffraction patterns, transmission electron microscopy images, Raman and selectively excited photoluminescence spectra. Measurement of the luminescence from the samples shows that the excited ZnO transfers the excited energy efficiently to the doped Eu3+ ions, giving rise to efficient emission at red spectral region. The red emission quantum yield is measured to be 31% at room temperature. The temperature dependence of photoluminescence and the photoluminescence excitation spectra have also been investigated, showing strong energy coupling between the ZnO host and Eu3+ ions through free and bound excitons. The result indicates that Eu3+ ion-doped ZnO nanocrystals are promising light-conversion materials and have potential application in highly distinguishable emissive flat panel display and LED backlights.