Surface hydrogen detection by low energy He ion scattering spectroscopy

Hydrogen adsorbed on a Si(100) surface can be detected by angle-resolved LEIS (low-energy ion scattering spectroscopy) which uses a ⁴He⁺ ion beam with incident energies around 1 keV. The scattering peaks from the surface hydrogen are restricted to narrow scattering angles from 0° to 15°, which is in agreement with those expected by the binary elastic collision model.     

Stability of stationary solutions of a semilinear parabolic partial differential equation

We consider a parabolic partial differential equation u_t = u_xx + f(u) on a compact interval of spatial variable x with Dirichlet boundary conditions. The stability of stationary solutions of this system is studied by the use of Liapunov's second method. We obtain necessary and sufficient conditions for the stability, asymptotic stability, neutral stability, instability, and conditional stability. These conditions are closely connected with the conditions for the existence of the stationary solutions.     

Analysis of temperature change effects on hologram recordingand a compensation method

For commercialization of holographic storage drives, the effects of temperature changes on holographic medium is critical. There has been no systematic study on the effect of temperature change on hologram recording properties. We believe that the monomer-diffusion speed and polymerization rate changes are critical for hologram-recording properties and estimate those parameters on each temperature using the photopolymer medium process simulation we have developed. We describe how these parameters affect actual recording properties such as sensitivity, M=# and so on. Moreover, we propose a method for compensating temperature changes, and confirm the success of this.     

Exploration of layered-type pseudo four-component Li-Ni-Co-Ti oxides

A series of layered-type pseudo four-component Li-Ni-Co-Ti oxides were prepared to explore optimal cathode materials for a lithium-ion secondary battery. The new layered-type compounds were prepared using a combinatorial material-preparation system based on electrostatic spray deposition (the “M-ist Combi” system), and combinatorial powder X-ray diffraction. The composition region of the new compounds (Li_α(Ni_xCo_yTi_z)O₂ (α∼1, 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, z∼0.2, x + y + z = 1.0)) was found to be wider than the composition region previously reported (LiNi_0.8−yCo_0.2Ti_yO₂ (0 ≤ y ≤ 0.1)).     

Synthesis and polymerization of chiral methacrylates bearing a cholesteryl or menthyl group

Chiral methacrylates, that is, cholesteryl (ChMOC) and l‐menthyl (MnMOC) N‐(2‐methacryloyloxyethyl)carbamates, were synthesized from 2‐methacryloyloxyethyl isocyanate and cholesterol and l‐menthol, respectively. Radical polymerizations of ChMOC and MnMOC gave number‐average molecular weights for poly(ChMOC) and poly(MnMOC) of up to 3.74 × 10⁴ and 9.39 × 10⁴, respectively, and the specific rotations ([α]) were −43.1° to −47.7° and −87.6° to −89.0°, respectively. Temperature dependence of the specific optical rotation was observed for poly(ChMOC) but not for poly(MnMOC). The hydrogen bonds based on urethane segments for poly(ChMOC) were stronger than those for poly(MnMOC) according to IR spectra. In addition, the chiroptical properties of poly(ChMOC) were slightly affected by temperature in the presence of trifluoroacetic acid acting as an inhibitor for the formation of hydrogen bonds. Therefore, poly(ChMOC) may have a regular conformation due to hydrogen bonds and interaction between cholesteryl groups. Radical copolymerizations of ChMOC with styrene, methyl methacrylate, N‐cyclohexylmaleimide, and N‐phenylmaleimide were performed with 2,2′‐azobisisobutyronitrile in tetrahydrofuran at 60 °C. Monomer reactivity ratios and Alfrey–Price Q–e were determined. Chiroptical properties of the copolymers were influenced by co‐units. Thermal and X‐ray diffraction analyses were performed for the homopolymers and copolymers. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4315–4325, 2000     

On the Origin of the Non-Arrhenius Na-ion Conductivity in Na3OBr

The sodium-rich antiperovskites (NaRAPs) with composition Na₃OB (B=Br, Cl, I, BH₄, etc.) are a family of materials that has recently attracted great interest for application as solid electrolytes in sodium metal batteries. Non-Arrhenius ionic conductivities have been reported for these materials, the origin of which is poorly understood. In this work, we combined temperature-resolved bulk and local characterisation methods to gain an insight into the origin of this unusual behaviour using Na₃OBr as a model system. We first excluded crystallographic disorder on the anion sites as the cause of the change in activation energy; then identified the presence of a poorly crystalline impurities, not detectable by XRD, and elucidated their effect on ionic conductivity. These findings improve understanding of the processing-structure-properties relationships pertaining to NaRAPs and highlight the need to determine these relationships in other materials systems, which will accelerate the development of high-performance solid electrolytes.