Jenny Schneider,*,† Masaya Matsuoka,‡ Masato Takeuchi,‡ Jinlong Zhang, Yu Horiuchi,‡ Masakazu Anpo,‡ and Detlef W. Bahnemann*,† †Institut fur Technische Chemie, Leibniz Universitaẗ Hannover, Callinstrasse 3, D-30167 Hannover, Germany ‡Faculty of Engineering, Osaka Prefecture University, 1 Gakuen-cho, Sakai Osaka 599-8531, Japan Key Lab for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237, China

Understanding TiO2 photocatalysis: mechanisms and materials.

The term photonic crystals appears because of the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures. During the recent years the investigation of one-, two-and three-dimensional periodic structures has attracted a widespread attention of the world optics community because of great potentiality of such structures in advanced applied optical fields. The interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.

http://ieeexplore.ieee.org/iel5/6354/16969/00781867.pdf

Photonic crystals

Physical Review B

Core–shell nanoparticles (CSNs) are a class of nanostructured materials that have recently received increased attention owing to their interesting properties and broad range of applications in catalysis, biology, materials chemistry and sensors. By rationally tuning the cores as well as the shells of such materials, a range of core–shell nanoparticles can be produced with tailorable properties that can play important roles in various catalytic processes and offer sustainable solutions to current energy problems. Various synthetic methods for preparing different classes of CSNs, including the Stober method, solvothermal method, one-pot synthetic method involving surfactants, etc., are briefly mentioned here. The roles of various classes of CSNs are exemplified for both catalytic and electrocatalytic applications, including oxidation, reduction, coupling reactions, etc.

Core–shell nanoparticles: synthesis and applications in catalysis and electrocatalysis

Phase-contrast x-ray imaging (PCI) is an innovative method that is sensitive to the refraction of the x-rays in matter. PCI is particularly adapted to visualize weakly absorbing details like those often encountered in biology and medicine. In past years, PCI has become one of the most used imaging methods in laboratory and preclinical studies: its unique characteristics allow high contrast 3D visualization of thick and complex samples even at high spatial resolution. Applications have covered a wide range of pathologies and organs, and are more and more often performed in vivo. Several techniques are now available to exploit and visualize the phase-contrast: propagation- and analyzer-based, crystal and grating interferometry and non-interferometric methods like the coded aperture. In this review, covering the last five years, we will give an overview of the main theoretical and experimental developments and of the important steps performed towards the clinical implementation of PCI.

http://iopscience.iop.org/article/10.1088/0031-9155/58/1/R1/pdf

X-ray phase-contrast imaging: from pre-clinical applications towards clinics

Lattice dynamical, dielectric, and thermodynamic properties of β-Ga2O3 are investigated by first principles. The calculated phonon frequencies for the Raman-active and the infrared-active modes are assigned. The phonon dispersion curves along high symmetry lines in the Brillouin zone and the phonon density of states are also calculated. The electronic and static dielectric tensors are calculated. The calculated static dielectric constants are much larger than the electronic constants, showing the rather strong ionic contributions to static dielectric constants. These calculated results are in a good agreement with available experimental values. The thermodynamic functions are calculated by using the phonon density of states.

Lattice dynamical, dielectric, and thermodynamic properties of β-Ga2O3 from first principles

We present first-principles calculations for fluorine-doped zinc oxide (ZnO:F) by using density-functional theory. Under O-poor condition, fluorine substitution for oxygen (FO) is energetically favorable in ZnO. FO can effectively diminish oxygen vacancies. With high fluorine concentration, fluorine interstitial (Fi) may appear. The high transition energies of FO and Fi suggest that FO and Fi could act as deep donor and acceptor which cannot provide free carriers in ZnO at room temperature. The increase of carriers and mobility in ZnO:F could not contribute from deep donor FO, but may be due to the surface passivation effect of fluorine.

First-principles study of fluorine-doped zinc oxide

Eu3+-activated borogermanate scintillating glasses with compositions of 25B2O3–40GeO2–25Gd2O3–(10−x)La2O3–xEu2O3 were prepared by melt-quenching method. Their optical properties were studied by transmittance, photoluminescence, Fourier transform infrared (FTIR), Raman and X-ray excited luminescence (XEL) spectra in detail. The results suggest that the role of Gd2O3 is of significance for designing dense glass. Furthermore, energy-transfer efficiency from Gd3+ to Eu3+ ions can be near 100% when the content of Eu2O3 exceeds x = 4, the corresponding critical distance for Gd3+–Eu3+ ion pairs is estimated to be 4.57 A. The strongest emission intensities of Eu3+ ions under both 276 and 394 nm excitation are simultaneously at the content of 8 mol% Eu2O3. The degree of Eu–O covalency and the local environment of Eu3+ ions are evaluated by the value of Ωt parameters from Judd–Ofelt analysis. The calculated results imply that the covalency of Eu–O bond increases with the increasing concentration of Eu3+ ions in the investigated borogermanate glass. As a potential scintillating application, the strongest XEL intensity under X-ray excitation is found to be in the case of 6 mol% Eu2O3, which is slightly different from the photoluminescence results. The possible reason may be attributed to the discrepancy of the excitation mechanism between the ultraviolet and X-ray energy.

Eu3+‐Activated Borogermanate Scintillating Glass with a High Gd2O3 Content

A study of energy transfer was performed in dysprosium–terbium-doped silicate glasses at room temperature. Enhancement of the Tb 3+ emission and a decrease in the Dy 3+ emission are observed as a result of energy transfer from Dy 3+ ions to Tb 3+ ions. The energy transfer efficiencies, transfer probabilities, as well as average donor–acceptor distances were also calculated. It is concluded that the energy transfer mechanism between Dy 3+ and Tb 3+ ion is mainly electric dipole–dipole in nature.

Mu Gu

Papers

Lattice dynamical, dielectric, and thermodynamic properties of β-Ga2O3 from first principles

First-principles study of fluorine-doped zinc oxide

Eu3+‐Activated Borogermanate Scintillating Glass with a High Gd2O3 Content

Enhancement of Tb3+ emission by non-radiative energy transfer from Dy3+ in silicate glass

Luminescence properties of Pr3+-doped transparent oxyfluoride glass–ceramics containing BaYF5 nanocrystals