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We report the magnetocaloric effect of the Tsai-type 1/1 quasicrystal approximants Au64Al22R14 (R = Gd, Tb, and Dy) with the space group of Im 3 . These approximants with the electron-per-atom (e/a) ratio of 1.72 exhibit a ferromagnetic transition in bulk at the Curie temperatures of 27, 15, and 9.5 K for R = Gd, Tb, and Dy, respectively, as confirmed by both magnetic susceptibility and specific heat measurements. The magnetic entropy change (ΔSM) of the materials for a field change of 7 T are 6.3, 4.4, and 4.8 J/K mol-R for R = Gd, Tb, and Dy, respectively. Other parameters related to the magnetocaloric effect, the adiabatic temperature change (ΔTad) and the relative cooling power (RCP) are also evaluated. We also discuss the obtained magnetocaloric effect of the approximants with relation to the recently reported unique magnetic order formed on the icosahedral clusters, a building unit of the Tsai-type 1/1 quasicrystal approximants.

A silver germanium oxide, Ag 2 GeO 3 , was developed as a novel photocatalyst for degradation of organic dyes. The chemical composition of the sample was investigated via the SEM/EDX, ICP-AES, and TG-DTA techniques. The general activity of the material was characterized by testing the photodegradations of typical organic dyes, such as Methylene Blue (one of the heteropolyaromatic dyes), Rhodamine B (one of the xanthene dyes), Fuchsin Acid (one of the sulfonic dyes), and Orange II (one of the azoic dyes). All of these dyes were degraded more than 90% within 25 min under the visible-light irradiation of Xe lamp. Besides, with a commercial white fluorescent lamp as testing light source (light intensity, 61 μW/cm 2 ), the efficient decolorizations and mineralizations of the organic dyes were achieved over this material: 79% (90%) of the organic carbon in the Methylene Blue (Rhodamine B) solution was photooxidatized to inorganic carbon forms, when these dyes were totally decolorized. The high performance of this material is due to the photophysical properties of the wide-visible-range absorption and response, and the sufficient oxidative potential of the top of the valence band.

A novel visible light sensitive photocatalyst, AgSbO3 was prepared by a conventional solid-state reaction method. This oxide belonging to a cubic-pyrochlore structure can absorb visible light with wavelength up to about 480 nm. From the band structure calculation, we found that the top of the valence band consists of the hybridized Ag 4d and O 2p orbitals and the bottom of the conduction band mainly consists of the Ag 5s and the Sb 5s orbitals. Photocatalytic activities were evaluated using O2 evolution from an aqueous silver nitrate solution and decomposition of gaseous 2-propanol under visible light irradiation. We found that AgSbO3 shows a higher O2 evolution activity than WO3 and 2-propanol can be mineralized by the AgSbO3 photocatalysis under visible light irradiation.

We report a multiple-metal oxide Ag2ZnGeO4 with cristobalite-related structure as a visible light-sensitive photocatalyst (Eg 2.29 eV) for dye degradation. The physical characteristics of the samples were examined by techniques such as XRD, UV–vis diffuse reflectance spectroscopy and SEM. The photocatalytic activity of Ag2ZnGeO4 was confirmed by Rhodamine B (RhB) and Orange II photodegradation in aqueous phase. After 360 min of visible light (λ > 420 nm) irradiation, the conversions of RhB and Orange II reached 100% and 69.2%, respectively. The electronic structure of Ag2ZnGeO4 was investigated by band structure calculation based on the density function theory (DFT). Results revealed that the hybridized Ag 4d10 and O 2p6 orbitals form the valence band top of Ag2ZnGeO4, which leads to a much narrowed band gap as compared with that of the Na2ZnGeO4 parent sample. We propose that the specific cristobalite structure of Ag2ZnGeO4 favors the mobility of photo-generated carriers, and that this contributes positively to the observed photocatalytic activity for dye degradation.

We report on the electronic structure of the bilayer ruthenate Ca 3 Ru 2 O 7 using high quality single-crystals grown by a floating-zone method which have the lowest residual resistivity so far achieved. The quantum oscillation, specific heat, and angle-resolved photoemission-spectroscopy (ARPES) measurements performed on these crystals establish that Ca 3 Ru 2 O 7 is a quasi two-dimensional low-carrier metal with a density-wave instability.

We report X-ray scattering studies of the c-axis lattice parameter in Ca3Ru2O7 as a function of temperature and magnetic field, for B || the ground state easy (b) axis. The step-like, ∼0.1% change coincides in zero field with a spin reorientation and a metal–insulator transition, at Tm−i≈48 K, and shifts to a lower temperature upon application of magnetic field. At temperatures well below Tm−i, negligible change in the c-axis lattice parameter is observed at the metamagnetic transition to the spin-polarized phase, at Bc≈6 T, which indicates that this transition does not couple to the lattice degree of freedom.