Key Engineering Materials Vol. 698

Abstract: Co/Pd magnetic multilayers have been prepared by using a sputtering method. Lattice distances and magnetic hysteresis curves have been measured by X-ray diffraction (XRD) measurements and magnetization measurements using a vibrating sample magnetometer (VSM). The XRD measurements have shown that the samples with thinner Pd layers have shorter lattice distances, and the VSM measurements have shown that the samples of thinner Co and thicker Pd layers are closer to those of perpendicular magnetic anisotropy. We have applied the X-ray magnetic diffraction method to the Co/Pd multilayer for the first time and have succeeded in observing a change in the X-ray diffraction intensities by the reversal of the magnetization direction.

Abstract: In this study, KAlSi₃O₈ was synthesized by a solid-phase reaction at 900, 1000 and 1100 °C, using K₂CO₃, Al₂O₃ and SiO₂ as the starting materials. The powder X-ray diffraction profile of the compound thus prepared was confirmed to contain a mixture of crystalline and glass phases. In addition, a higher sintering temperature of greater than 1000 °C possibly led to the decrease in the crystalline phase. From the temperature dependence of dc conductivity, activation energies for ionic transport were estimated to be 0.79–0.84 eV. The frequency-dependence of the real part of electrical conductivity suggests that the mechanism of ionic transport in the dispersion region possibly depends on the crystallinity of KAlSi₃O₈.

Abstract: We fabricated Si:SiO₂ films and assessed its characterization of photoluminescence and surface chemistry. When Si tablets on a SiO₂ target were sputtered in a chamber of a radio frequency sputtering device, Si:SiO₂ films were deposited on a substrate. When the films were excited by a He-Cd laser, photoluminescence having wide and continuous peaks was emitted in shorter region than 600 nm. After annealing, intensity of photoluminescence changed, which depends on annealing temperature and time. By the Fourier Transform InfraRed Spectroscopy, bonds of atoms around Si were investigated.

Abstract: A control and utilizability of spatial fluctuations in polymer capacitors using immiscible binary mixtures are described. The spatial fluctuations for the device elements are of particular important for bioinspired multielemental network devices that is composed of elements with distributed electric property. Here we first report that spatial distribution of dielectric properties can be enhanced on the fabrication of SDDE using thermal processing that changes the morphology of immiscible PLLA/PCL binary mixture.

Abstract: The effect of the introduction of a CF₃ group to a silyl-anchor moiety of the sensitizer on the sensitizing property for the dye-sensitized solar cell was examined by using alkoxysilyl-anchor azobenzene dyes. The cell sensitized by the silyl-anchor dye with the electron-withdrawing CF₃ group in the silyl-anchor moiety exhibited higher photovoltaic performance than that by the silyl-anchor dye without the CF₃ group.

Abstract: In this paper, the effect of humidity and sample bias on the size of nanostructures fabricated by STM anodization on a 3 nm-thick Ti film was investigated by random nano-arrays. 3.5 V and 4 V bias were applied to samples at a relative humidity of ~30% while 3.5 V, 4 V and 4.5 V were applied to samples at a relative humidity of ~43%. According to the cross section analyses, dots scattered randomly on surfaces became larger and higher as the bias increased at a constant relative humidity or as the relative humidity increased at the same bias. Two complicated patterns were fabricated by running a program in which the movement of STM tip and the sample bias were defined.

Abstract: Pd supported on TiO₂-embedded carbon nanofibers (Pd/TECNF) were prepared as the anode catalyst for direct formic acid fuel cells (DFAFCs) using an electrospinning technique. The effect of the TiO₂ content on the catalytic activity of Pd was investigated based on the electrochemical measurements of cyclic voltammetry (CV), chronoamperometry (CA), and also characterization by XRD, EDX, FE-SEM and CO stripping. The activity was significantly increased by an increase in the TiO₂ content up to Ti/C=0.44 and then decreased. The maximized activity was improved eight fold by the TiO₂ addition. The increased activity was attributed to the increased electrochemically active surface area due to the modified surface of the nanofibers.

Abstract: The technical issue of direct ethanol fuel cells is slow kinetics of ethanol electrooxidation by using noble metals such as Pt. We propose silica-embedded carbon nanofiber (SECNF) as a catalyst support for the electrooxidation of ethanol to improve catalytic activity of Pt. SECNF was prepared by electrospinning, then Pt nanoparticles were deposited on SECNF. Catalyst characterizations were performed by SEM, EDX, and XRD. Cyclic voltammetry was performed to analyze catalytic activity of Pt/SECNF. The mass activity of Pt/SECNF was 2.9 times higher than a commercially available Pt/carbon catalyst (Pt/C_com). Electrochemically active surface area of Pt/SECNF was lower than Pt/C_com. Hence, the activity enhancement is attributed to the improvement of specific activity for Pt/SECNF. This enhancement is attributed to the interaction between Pt and SiO₂ like hydrogen spillover. Pt/SECNF is a promising catalyst for direct ethanol fuel cells which can reduce Pt loading.

Abstract: Optical sensors are commonly used and most of them detect the variation of light intensity and then if there is the uctuation of light source intensity or change in propagation loss it causes measurement errors. A ring laser sensor is one of the potential candidates which are insensitive to such uctuation, but it has mainly two problems. One is lock-in effect and the other is insensitiveness to detect the sign (polarity) of the sensing signal. To solve these problems a new phase control system has been proposed. It consists of two polarizers, two quarter-wave plates, and one Faraday rotator. Using this system the phase is controlled by the simultaneous rotation of two quarter-wave plates.

Abstract: Powder samples of (Ca,Sr)TiO₃:Er were prepared by a solid-state reaction method. Photoluminescence due to f-f transitions of Er³⁺ was not induced by band-gap excitation of (Ca,Sr)TiO₃ but by f-f transitions of Er³⁺. An electroluminescent device in which thin films of Ca_0.6Sr_0.4TiO₃:Er and SnO₂:Sb are stacked alternately was prepared by sol-gel and spin-coating methods. Very weak electroluminescence due to f-f transition of Er³⁺ was observed in the device.