Yttria-stabilized zirconia (Zr0.92Y0.08O2-δ:YSZ) thin films have been prepared on Al2O3 (0001) substrates by RF magnetron sputtering. The as-deposited YSZ thin films prepared at 500 ºC exhibited the (111) and (200) peak at 2θ values of 30.0º and 34.8º, respectively, which close to the peak positions of the YSZ single crystal. The Zr4+, Y3+ valence states and valence band were confirmed by photoemission spectroscopy. When the as-deposited YSZ thin films were annealed in the saturated H2O atmosphere, the Fermi level shifted to conduction band side by 1.0 eV. The above result indicates that the proton of the H2O annealed YSZ thin film acts as donor ions in the surface state.
We grew transparent SrB4O7 (SBO) crystal fibers by the micro-pulling-down (μ-PD) method at pulling rates (VP) of 0.01–0.40 mm/min. We observed the SBO crystals by optical microscopy. The SBO crystal fiber at VP of 0.40 mm/min was cloudy due to the incorporation of voids. In contrast, transparent single-crystal fibers were obtained at VP of less than 0.02 mm/min. This is the first time that transparent SBO crystal fibers have been grown with a length of several centimeters. These results demonstrate that it is crucial to grow SBO crystals at a low VP to obtain transparent crystal fibers. In addition, we considered the generation mechanism of voids in the SBO crystals by using the relation between the growth rate of SBO crystals and the diffusion rate of voids.
A heat-engine using Ti-Ni shape memory alloy (SMA) driven by low-temperature waste heat energy has been investigated for waste heat recovery potential system. We had proposed the use of the tape-shaped SMA element because of the cooling efficiency improvement of the SMA element. However, the manufacturing cost of the tape-shaped SMA fabricated by arc melting method is higher than that of a wire or coil shaped SMA. To reduce the manufacturing cost, we fabricated a tape-shaped SMA element by the centrifugal casting method using an alloy fabricated by the powder metallurgy method, and investigated the effect of heat-treatment temperature on shape memory characteristics of this tape-shaped Ti-Ni SMA specimen fabricated by the centrifugal casting method. The mechanical and shape memory properties of tape-shaped SMA specimen show a minimum at 803 K, and it increases as temperature rises up to 953 K, above which it decreases. The fluctuation of mechanical and shape memory properties are caused by the variation of dislocation density, secondary phase and precipitated phase. From these results, it was found that the optimum heat-treatment temperature of the tape-shaped Ti-Ni SMA specimen is 953 K. Moreover, the output properties of SMA heat-engine driven by an SMA element fabricated by the centrifugal casting method, is superior to the output properties of the heat-engine using an SMA element fabricated by arc-melting method.
Sn doped SiO2 thin films, which show strong luminescence by UV excitation, were prepared by a sputtering deposition method using a SnO2 and SiO2 powder mixed target. Optical emission spectrum of the plasma using powder target was almost same compared with the conventional sputtering deposition method SiO2 bulk target and Sn atoms were identified in the emission spectrum. XRD and XPS measurements suggest that Sn doped SiO2 thin films can be prepared using SnO2 and SiO2 mixture powder target, and their properties depend on the SiO2 mixture in the target.
We demonstrated that complex flocculation of biofilm-forming Pseudomonas aeruginosa PAO1 and Bacillus cereus SM-5 occurred in the presence of floc-forming Pseudomonas oryzihabitans AO-363 isolated from activated sludge. Laser diffraction analysis showed a drastic decrease in the detected frequency of planktonic PAO1 cells (1.3 μm) after they were mixed with AO-363 flocs. In addition, the most frequent diameter of SM-5 flocs shifted from 152 to 175 μm after mixing with the AO-363 culture. Complex flocculation was also supported by analysis of the bacterial composition of the floc fraction obtained by low-speed centrifugation. Such complex microbial flocs could contribute to the development of biofilms on polystyrene surfaces. When AO-363 was co-cultured with PAO1 or SM-5, the amount of biofilm formation increased by 3-4 times compared to that in the absence of the floc-forming AO-363 cells. These results suggest that microbial flocs containing extracellular polymeric substances (EPS) could increase the development of biofilms that contain bacterial colonies and the EPS components.
Our recent study elucidates that information of density of states in configuration space (CDOS) for noninteracting system, characterized by spatial constraint on the system, plays essential role to determine thermodynamically equilibrium properties for interacting systems. Particularly for disordered states, variance of CDOS along all possible coordinations plays significant role. Despite this fact, even for binary system of crystalline solids, expression for variance of CDOS as a function of composition has not been clarified so far. Here we successfully derive expression for variance of CDOS as a function of composition for pair correlations, whose validity is demonstrated by comparing the results with uniform sampling of CDOS on real lattices. The present result certainly advances determining special microscopic state to characterize Helmholtz free energy in classical systems, whose structure is difficult to determine by numerical simulation.
When spatial constraint for the constituents (e.g., atom or particle) of system is once given, disordered structure for non-interacting system in equilibrium states is symmetric with respect to equiatomic composition. Meanwhile, when the interaction between constituents is introduced, this symmetry is typically broken, naturally appearing compositional asymmetry. Although this asymmetry, depending on temperature, comes from multibody interactions in the system, we here clarify that the asymmetry near equiatomic composition can be universally well-characterized by two specially selected microscopic structure, which can be known a priori without any information about interactions or temperature: The key role is the class of spatial constraint. Based on the facts, we provide analytical expression of temperature dependence of disordered structure, and demonstrate its validity and applicability by predicting short-range order parameters of practical alloys compared with full thermodynamic simulation.
Zinc gallium oxynitride, (Ga1-xZnx)(N1-xOx), was synthesized by the reaction of zinc gallium oxynitride, ZnGa2O4, with a solid nitrogen source of Li3N at 823 K. A thermolysis of the mixture of gallium salen and zinc acetate produced ZnGa2O4 particles with a 2D morphology. The optimization of zinc and gallium ratio was examined in synthesizing ZnGa2O4. After nitridation, zinc gallium oxynitride with a cauliflower-like morphology was produced as a major product for zinc-rich precursor, whereas LiGaO2 and GaN were the major products for zinc-poor precursor.
We conducted elemental analysis on several kinds of excavated natural whetstones and Owari-Shippo enamel ware at the Owari Clan Upper Mansion Site using X-ray Fluorescence (XRF) analysis. The minor element concentrations of two types of excavated tuff are consistent with those used for polishing Owari-Shippo.