Key Engineering Materials Vol. 643

Abstract: We demonstrate the possibility of forming long-range-ordered self-assembled nanodot arrays with dots size of 5 nm and pitches of 10×7.5 nm² using guide line templates and low molecular weight (MW) (4,700–1,200 g/mol) poly (styrene)-poly (dimethylsiloxane) (PS-PDMS) for application in ultrahigh density patterned media. The self-assembled PDMS nanodots are controlled in a long range by varying the heights and gaps of the guide lines. Adopting the 14-nm-high resist guide lines with suitable gaps, the 5-nm-sized and 10×7.5 nm²-pitched self-assembled nanodots were ordered in maximum 7 dot arrays with long-range order. The experimental results demonstrate that the method is possible for achieving patterned media with magnetic recording densities of 8.6 Tbit/in.² using low MW PS-PDMS and slim guide lines.

Abstract: In this study, we tried to develop the scanning near-field polarization microscope (SNPM) and challenge to observe magnetization of the magnetic nanodot in the arrays. The CoPt dot arrays with a size of 25 nm and a pitch of 150 nm were adopted. The nanodots change contrast after changing the direction of the external magnetic field. This implied that our prototyped SNPM system had the resolution of less than 25 nm. So, it is demonstrated that SNPM is an effective tool for the observation of magnetization of the magnetic nanodot on the nanometer scale.

Abstract: Microstructure patterning in single-crystal chemical vapor deposition (SC-CVD) diamond films was investigated to establish a direct patterning procedure by using proton beam writing with a focused microbeam of protons. Test microstructural patterns on SC-CVD diamond with different total fluences from 0.5 to 10 pC/μm² were formed with a probe diameter of approximately 1 μm, a maximum scanning area of 800 × 800 μm, and a beam current of up to 100 pA. The most intensively irradiated pattern with beam fluence of 10 pC/μm² was visualized with both transmission and reflection optical microscopy. The other patterns created with lower beam fluences were characterized by the changes in reflective index and were visible only in the transmission microscopy images. The depth of patterns was precisely controlled by changing proton energies in range of 0.75–3 MeV. The structures in depth from 5 to 45 μm were successfully observed in optical microscope images.

Abstract: Allylsilyl and hydrosilyl groups were examined as the anchor moieties of sensitizing dyes for dye-sensitized solar cells by using silylazobenzene dyes. Allylsilyl and hydrosilyl dyes were observed to adsorb efficiently onto TiO₂ electrodes and the dye-adsorbed electrodes exhibited high durability to water. Light-to-electric energy conversions were also confirmed in the cells using the dye-adsorbed electrodes. The results show a high potential of allylsilyl and hydrosilyl dyes as the sensitizing dyes.

Abstract: Enhancement of optical transmittance of polymer-dispersed liquid crystal (PDLC) cells was investigated by introducing a modification into the substrates. Surface treatment by rubbing was performed on both network-type and droplet-type PDLCs to investigate the effect on the optical transmittance of the cells. Differences in the transmittance of the PDLC in the polymer matrix were observed by introducing rubbing effect on network-type PDLC but not on droplet-type PDLC. These phenomena might be used to distinguish the application field of both types of PDLC cells by enhancing optical transmittance and scattering properties.

Abstract: Oxide inorganic electroluminescent device in which thin films of Pr-doped NaNbO₃ phosphor and Sb-doped SnO₂ transparent conductor are alternately stacked was prepared by sol-gel and spin-coating methods. Red electroluminescence was observed due to f-f transitions of Pr³⁺ ions by applying 5-kHz ac voltages to the device. The luminance was 1.0 cd m⁻² at 25 V ac and5.0 cd m⁻² at 34 V ac.

Abstract: We have applied two kinds of experimental methods using elliptically polarized synchrotron X-rays, magnetic Compton and Bragg scattering experiments, to a single crystal of a disordered Pd_0.80Co_0.20 alloy, and have measured magnetic Compton profiles and magnetic form factors, respectively. The result of the Compton scattering experiment has shown that the electronic structure of Pd_0.80Co_0.20 is similar to that of Pd_0.72Co_0.28, and the spin moment has been evaluated. The result of the Bragg scattering experiment has reinforced that of the previous experiment [M. Ito et al.: Mater. Sci. Forum Vol. 459 (2011), p. 3.], and the spin moment estimated by the magnetic Bragg scattering has reproduced that by the magnetic Compton scattering. These results show that the joint study of the magnetic Compton and Bragg scattering provides a tool for investigating the magnetic property of alloys.

Abstract: This paper proposes a single inductor dual output (SIDO) DC-DC converter with an exclusive control circuit. We propose two kinds of converter: a buck-buck and a boost-boost converter. Multiple voltage outputs are controlled exclusively, using error voltage feedback. This approach requires a few additional components (a switch, a diode and a comparator), but requires no current sensors and does not depend on the value of output voltage or output current. We describe circuit topologies, operation principles and simulation results.

Abstract: This paper describes applications of a Delta-Sigma (ΔΣ) modulator to control a DC-DC converter. We propose to use a continuous-time (CT) feed-forward (FF) ΔΣ controller in a DC-DC converter and show that its transient response is faster than discrete-time (DT) and/or feedback-type (FB) ΔΣ controllers. We have also performed experiments of a DC-DC converter with a first-order continuous-time feedback ΔΣ controller and show its results.