Fabrication and piezoelectric properties of BaTiO3/BaTiO3-Bi(Mg1/2Ti1/2)O3-BiFeO3 composites

We fabricated xBaTiO₃ (BT)/(1-x)[BaTiO₃-Bi(Mg_1/2Ti_1/2)O₃-BiFeO₃] (BT-BMT-BF)?+?0.1?wt%MnCO₃ composites by spark plasma sintering and investigated the effect of BT content x, BT powder size, and BT-BMT-BF composition on piezoelectric properties. For xBT/(1-x)(0.3BT-0.1BMT-0.6BF) +?0.1?wt%MnCO₃ (x?=?0–0.75) composites with a 0.5-µm BT powder, the dielectric constant was increased with x, and the relative density was decreased at x?=?0.67 and 0.75, creating optimum BT content of x?=?0.50 with a piezoelectric constant d₃₃ of 107?pC/N. When a larger 1.5-µm BT powder was utilized for the composite with x?=?0.50, the d₃₃ value increased to 150?pC/N due to the grain size effect of the BT grains. To compensate for a compositional change from the optimum 0.3BT-0.1BMT-0.6BF due to partial diffusion between the BT and 0.3BT-0.1BMT-0.6BF grains, a 0.5BT/0.5(0.275BT-0.1BMT-0.625BF)?+?0.1?wt%MnCO₃ composite with the 1.5-µm BT powder was fabricated. We obtained an increased d₃₃ value of 166?pC/N. These results provided a useful composite design to enhance the piezoelectric properties.     

Super environment-friendly electrodeposition paint

Super low VOC due to new composition/reaction mechanism can minimize the environmental risk as it does not contain lead and tin, hazardous air pollutants (HAPs) and endocrine disrupters (EPA/67 items, SPEED’98/JEA/67 items) currently specified as contaminants. New EAD (electrolyzed activate deposition paint) is not the only conventional cure agent or solvent, but also the super low VOC, HAPs materials and endocrine disrupters. The electric energy used by EAD is utilized for the reaction but not for the deposition. EAD consists of two technologies. One is propargyl group change to the allene by using electrodeposition. Propargyl group is stable, but allene group is highly polymerizing. As a result, EAD had high bath stability. The other is sulfonium change to sulfide by using electrodeposition. This sulfonium salt is lost as a result of the electrolytic reduction, and hence can be irreversibly rendered non-conductive. As a result, EAD showed high throwing power.     

Fabrication of 0.24Pb(In1/2Nb1/2)O3-0.42Pb(Mg1/3Nb2/3)O3-0.34PbTiO3 transparent ceramics by conventional sintering technique

0.24Pb(In_1/2Nb_1/2)O₃-0.42Pb(Mg_1/3Nb_2/3)O₃-0.34PbTiO₃ transparent ceramics were fabricated by a conventional sintering technique. Through optimization of sintering conditions of calcination and sintering temperatures and time, the obtained ceramics showed high optical transmittance of 53% and 71% at light wavelengths of 1300 and 2000 nm, respectively. The ceramics showed a rhombohedral to tetragonal phase transition at ~120°C and a tetragonal to cubic phase transition at 222°C. These transition temperatures were higher than those of 0.67Pb(Mg_1/3Nb_2/3)-0.33PbTiO₃ ceramics. In addition, the ceramics had a ferroelectric hysteresis loop, a large piezoelectric constant d₃₃ of 407 pC/N, and a planar electromechanical coupling factor k_p of 52%. These results suggest that the transparent ceramics may be used as a temperature-stable, linear electro-optic material.     

Phase Relationships and Physical Properties of Homologous Compounds in the Zinc Oxide-Indium Oxide System

Equilibrium phase relationships in the ZnO-In₂O₃ system were determined between 1100° and 1400°C using solid-state reaction techniques and X-ray diffractometry. In addition to ZnO and In₂O₃, nine homologous compounds, Zn _k In₂O _{k +3} (where k = 3, 4, 5, 6, 7, 9, 11, 13, and 15), were observed. Electrical conductivity and diffuse reflectance of the k = 3, 4, 5, 7 and 11 members were measured before and after annealing at 400°C for 1 h under forming gas (4%₂-96% N₂). Room-temperature conductivity increased as k decreased, because of increased carrier concentration as well as increased mobility. In general, transparency in the wavelength range of 450-900 nm increased as k increased. Reduction in forming gas resulted in increased conductivity and reduced transparency for all compounds measured. The highest room-temperature conductivity measured, 270 S/cm, was that of reduced Zn₃In₂O₆.     

Effect of Firing Temperature on the Thermal Stability of Low-Oxygen Silicon Carbide Fibers

Low-oxygen SiC fibers which were fabricated by curing with electron-beam irradiation and firing at 1273 and 1573 K (fiber-A and fiber-B) were exposed at 1673 to 1973 K. Significant differences in surface composition, crystallinity, specific resistivity, and tensile strength were found between fiber-A and fiber-B. On exposing the fibers to high temperatures, they both crystallized nearly completely into intermixed β-SiC and free carbon, and consequently the resistivity decreased markedly. Deep voids were formed at the surface of fiber-A as a result of rapid dehydrogenation at the earliest stage of high-temperature exposure. On the other hand, fiber-B, which decomposed mildly, had a dense pore-free structure. The fiber strength was proportional to the reciprocal square root of SiC crystal size. At the same crystal size, the strength of fiber-A was lower because of the surface flaws.     

Quantitative evaluation of perceived whiteness based on a color vision model

This article describes a new perceived whiteness index, C/V index, which focuses on the brightness‐enhancement effect of color components included in the spectral reflectance factor distribution of approximate white objects or in the spectral power distribution of illuminations. The index is developed on the basis of a color vision model. The perceived whiteness of 18 approximate white samples was evaluated, and then a predictability of the index was compared with 17 types of existing whiteness indices. As a result, the C/V index was one of the indices indicating the best predicting performance. The aforementioned findings show that the C/V index is effective in evaluating the perceived whiteness of approximate white objects and the brightness‐enhancement effect of color components is an important factor in determining the perceived whiteness. © 2009 Wiley Periodicals, Inc. Col Res Appl, 2010     

THz-wave absorption by field-induced carriers in pentacene thin-film transistors for THz imaging sensors

Innovative sensing systems based on THz electromagnetic waves have been attracting a great deal of attention. Although many THz detectors have been developed over the years, it is currently difficult to manufacture low-cost THz sensing/imaging devices. In the present study, we propose to use organic field-effect transistors (OFETs) and small potential fluctuation against the carriers within them (N. Ohashi, H. Tomii, R. Matsubara, M. Sakai, K. Kudo, M. Nakamura, Appl. Phys. Lett. 91 (2007) 162105). We use THz time-domain spectroscopy for OFETs in which the carrier density in the pentacene active layer is modulated by the gate bias. We found evidence that the accumulated free holes in pentacene films can be excited by THz photons to overcome the surrounding barriers in the fluctuating potential. The Drude–Lorentz model could not account for the shape of the absorption spectra, which suggests that the holes are weakly restricted by the potential fluctuation. The integrated absorption intensity was proportional to the transfer characteristics of the OFETs. The present findings represent an important step toward developing a new class of THz-wave sensors.     

Fast Labelling of Natural Scenes Using Enhanced Knowledge

A new technique for labelling natural scenes is proposed. This technique labels disjoint regions on an image of a natural scene on the basis of knowledge about the relationship among objects. The proposed technique consists of three stages: (1) segmentation, (2) initial labelling, and (3) label improvement. One of the most promising previous techniques uses simulated annealing to find the solution, while our technique uses local hill-climbing with enhanced knowledge for speeding up the processing. Local hill-climbing is known to be easy to be captured by a local minimum. We solved this problem by enhancing the knowledge being used as constraints for the search. Our knowledge represents 1-to-n relationships among regions, pair-wise relationships of regions, and relative locations of the regions to the image. In addition, we introduced two region features: an entropy in intensity; and a linearity of contours of each region. The linearity evaluation aims to distinguish artificial objects from natural objects. The validity of the technique is supported by some experiments. These experiments showed that the proposed technique is much faster with the almost same accurate.