High pressure form of fluoride garnets Na3M2Li3F12 (M=Al & Fe)

The fluoride garnet, Na₃Fe₂Li₃F₁₂, transforms to a single phase with the cryolite (ordered perovskite) structure under 60 kb above 400°C. The lattice constants, a=5.338, b=5.498, c=7.666 Å and β=90.0°, are smaller than those of Na₃FeF₆, due to the substitution of Na for Li ions in the structure. The measurements of magnetic susceptibility and Mössbauer effect indicate that Fe ions are in the high spin trivalent state and in octahedral site. Na₃Al₂Li₃F₁₂, cryolithionite, decomposes to the cryolite and α-Li₃AlF₆ under high pressures examined.     

High-pressure modifications of CaAl2O4 and CaGa2O4

The modifications of CaAl₂O₄ and CaGa₂O₄ with the stuffed tridymite structure were examined under high temperatures (600 ～ 1500 °C) and high pressures (10 ～ 40 kb). Calcium monoaluminate CaAl₂O₄ was found to transform to three kinds of high-pressure modifications. The original CaAl₂O₄ (CA-I) changed to the phase CA-II which had m-CaGa₂O₄ type structure with a different array of tetrahedra in the six-membered rings of tetrahedron. The phase CA-II transformed either to the phase CA-IV with CaFe₂O₄ type structure or to an unknown phase (CA-III) under high pressures. The phase CA-IV was obtained under the pressures above 30 kb and at the temperatures above 1000 °C. Calcium monogallate CaGa₂O₄ transformed to the CaFe₂O₄ type structure above 30kb and 700 °C. No phases such as CA-II and CA-III were found. The structural relations among these modifications were discussed.     

Preparation and characterization of stoichiometric CaFeO3

Stoichiometric CaFeO₃ was prepared and was characterized by crystallographic, magnetic and electrical measurements. A slight tetragonal distortion from the ideal cubic perovskite structure was found. The tetramolecular unit cell has a = 5.325 (3) A and c = 7.579 (5) A. The susceptibility showed a maximum at about 115 K and the temperature dependence of electrical resistivity changed from metallic to semiconductive in the vicinity of the magnetic transition temperature. These indicate a phase transition from the metallic-paramagnetic (the high-temperature phase) to the semiconductive-antiferromagnetic phase. The Mössbauer spectra indicated that a charge disproportionation 2Fe⁴⁺ → Fe³⁺ + Fe⁵⁺ associates with the transition.     

Spherical tokamak generation and merging on UTST using ex‐vessel poloidal field coils only

We successfully generated two spherical tokamaks (ST) at two null points by using ex‐vessel poloidal field (PF) coils only and succeeded in merging them. This scheme is called a double null merging (DNM) scheme. First, two pairs of ex‐vessel PF coils generate two null points where the poloidal field is zero at the upper and lower regions inside the vacuum vessel. Then a poloidal flux swing generates two STs at two null points, because the distance to the wall along the magnetic field is long at the null points. Finally, the coil currents push two STs toward the mid‐plane and merge them into a single ST. Since a magnetic reconnection during merging transforms magnetic energy into thermal energy, this merged ST plasma is expected to have a high beta. It must be noted that the DNM scheme generates an ST without a center solenoid coil. The DNM scheme was demonstrated on the TS‐3/4 (Japan) and MAST (UKAEA). However, these devices have all PF coils inside the vacuum vessels, and the initial plasmas were generated around the PF coils, not the null points. Since internal coils are not feasible in a fusion reactor due to high neutron flux, it is important to demonstrate the DNM scheme by using ex‐vessel PF coils. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 179(4): 18–24, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21254     

Origin of enhanced electrical and conducting properties in pentacene films doped by molybdenum trioxide

Molybdenum trioxide (MoO₃) doped organic semiconductors have shown attractive applications in organic electric devices. The authors carried out an investigation on the origin of enhanced photoelectric characteristics in MoO₃-doped pentacene films. Electrical properties including charge transport, trap density and conductivity in bulk MoO₃-doped pentacene films were investigated through fundamental measurements of current-voltage characteristics. Electrical structure and conducting mechanism in MoO₃-doped pentacene films were further evaluated by X-ray diffraction and X-ray photoelectron spectroscopy measurements. The experimental results suggest that the improved conductivity in MoO₃-doped pentacene film was partly associated with the increased ratio of low Mo oxidation state (Mo⁴⁺) with a fact of better conducting property of MoO₂ than that MoO₃.     

Identification of the Sex Pheromone Secreted by a Nettle Moth, Monema flavescens, Using Gas Chromatography/Fourier Transform Infrared Spectroscopy

The nettle moth Monema flavescens (Limacodidae) is a defoliator of fruit trees, such as Chinese plum and persimmon. The larvae of this species have spines containing a poison that causes serious irritation and inflammation in humans. Coupled gas chromatography-electroantennogram detection and gas chromatography/mass spectrometry analyses of a crude pheromone extract, combined with derivatization, indicated that female moths produced 8-decen-1-ol and 7,9-decadien-1-ol at a ratio of approximately 9:1. The E configuration of the double bonds was assigned for both components from infrared spectra, recorded on a gas chromatograph/Fourier transform-infrared spectrophotometer equipped with a zinc selenide disk cooled to ?30 °C. The monoenyl and dienyl alcohols had absorptions characteristic of E geometry at 966 and 951 cm^?1, respectively. A band chromatogram at 951 cm^?1 was useful for distinguishing geometric isomers, because terminal conjugated diene are difficult to resolve, even on high polarity columns. Furthermore, we identified the Z configuration of the same 7,9-dienyl alcohol secreted by another nettle moth, Parasa lepida lepida, through the absence of this absorption. In field trials, lures baited with a 9:1 mixture of (E)-8-decen-1-ol and (E)-7,9-decadien-1-ol attracted M. flavescens males. Furthermore, the field trials indicated that contamination with the (Z)-diene reduced catches to the pheromone mixture more than did contamination with the (Z)-monoene.     

Stress analysis of Si1−xGex embedded source/drain junctions

The purpose of this paper is to evaluate the impact of the geometry of embedded Si_1−xGe_x source/drain junctions on the stress field. Stress simulations were performed using TSUPREM4 2D software to further investigate the elastic strain relaxation as a function of Si_1−xGe_x alloy active size, in the regime where no plastic relaxation is present. Moreover, the role of the epilayer thickness and the Ge content on the stress levels is also discussed. The work is complemented with experimental Raman spectroscopy.     

Influence of ITO patterning on reliability of organic light emitting devices

Indium tin oxide (ITO) films are widely used for a transparent electrode of organic light emitting devices (OLEDs) because of its excellent conductivity and transparency. Two types of ITO substrates with different surface roughness were selected to use as anode of OLEDs. In addition, two types of etching process of ITO substrate, particularly the etching time, were also carried out. It was found that the surface roughness and/or the etching process of ITO substrate strongly influenced on an edge of ITO surface, further affected the operating characteristics and reliability of devices.     

Inline amplifier transmission experiments over 4500 km at 2.5 Gb/s

An inline amplifier system was constructed with erbium-doped fiber amplifiers spaced at 100 km and 80 km intervals. The system transmits 2.5 Gb/s signals over 2500 km with continuous-phase frequency-shift-keying heterodyne detection and over 4500 km with intensity-modulation direct detection. With respect to amplifier output signal power levels, it is experimentally shown that there exists a dynamic range within which long-distance signal transmission can be achieved with only small receiver sensitivity degradation. The range's upper and lower limits are determined by fiber nonlinearities and amplifier noise characteristics, respectively