Potential advantage of multiple alkali metal doped KNbO3 single crystals

Potassium niobate crystal KNbO3 (KN) is a well-known crystal for lead free piezoelectric or nonlinear optical applications. The KN crystal has been studied in both single crystal form and in thin film form which has resulted in many review articles being published. In order to exceed the KN crystal, it is important to study KN phase forming and doping effects on the K site. This article summarizes the authors\u27 study towards a multiple alkali metal doped KN crystal and related single crystals briefly from the viewpoint of crystal growth

Accelerating a Black Hole in Higher Dimensions

Utilising the master equation with source for perturbations of the Schwarzschild-Tangherlini solution, we construct perturbative solutions representing a black hole accelerated by a string in higher dimensions. We show that such solutions can be uniquely determined by a single function representing the local tension of the string, under natural asymptotic and regularity conditions. We further study whether we can construct a localised braneworld black hole solution from such a solution by cutting off a region containing the string by a hypersurface and putting a vacuum brane on the boundary. We find that the solution corresponding to the string with constant tension does not allow such brane configuration when the bulk spacetime dimension is greater than four, in contrast to the four dimensional case. Further, we show that there exist infinitely many localised braneworld black hole solutions in the perturbative sense for four-dimensional bulk spacetime, if we allow non-uniform string tensions.Comment: 47 pages, 4 figure

Dehydrogenative Polymerization of 3,5-Disubstituted p-Coumaryl Alcohols

この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されました。3,5-Disubstituted p-coumaryl alcohols (3-methoxy-5-iodo-, 3,5-diiodo-, 3-methoxy-5-nitro-, 3,5-dinitro-, 3,5-dimethoxy- and 3,5-dimethyl-p-coumaryl alcohols) were synthesized and dehydrogenated to their dimeric compounds with ferric chloride in dioxane (nonpolar solvent) and acetone-water (polar solvent), respectively. Yields of the β-ethers were, for example, 85 % (sinapyl alcohol) and 86 % (3, 5-diiodo-p-coumaryl alcohol) in dioxane, and 11% (the former) and 80 % (the latter) in acetone-water, respectively. These results suggest that the most effective factor in the radical coupling of these alcohols is the electronic effects of the substituent groups, but not the steric hindrance. Syringylglycerol-β-sinapyl ether was obtained in a high yield from sinapyl alcohol when dioxane was used as a solvent

Crystal growth of alkali metal ion doped potassium niobate fiber single crystals

Alkali metal (Na, Rb or Cs) ion doped KNbO3 fiber single crystals are grown using an original pulling down method, to improve their composition change during a crystal growth, by means of co-doping of small ionic size Na and large ionic size Rb or Cs into KNbO3. In spite of the co-doping, single crystals can be grown with orthorhombic single-phase at room temperature, as well as pure KNbO3. Their electric properties, such as impedance, are changed depending on the doping ions. Na and Rb co-doped KNbO3 is promising Pb free ferroelectric and piezoelectric crystals

Potassium-sodium-rubidium niobate single crystals and electric properties

Potassium-sodium-rubidium niobate single crystals are grown using an original pulling down method, to improve their composition change during a crystal growth, by means of co-doping of small ionic size sodium and large ionic size rubidium into potassium niobate. Even by the co-doping, single crystals can be grown with orthorhombic single-phase at room temperature, as well as pure potassium niobate. Their electric properties, such as the dielectric constant and the impedance, are changed depending on the doping ions

Density of states, magnetic and transport properties of Nd doped two dimensional perovskite compound Sr2CoO4

Structures, transport, magnetic properties, and first principle calculation results will be reported for the two dimensional layered structured perovskite compounds Sr2-xNdxCoO4 (x = 0.5, 0.75, 1, 1.25). Structure refinement results revealed that these compounds crystallized in K2NiF4-type structures with space group I4/mmm. The temperature dependence of resistivity showed semiconductor like behavior for these samples. It was found that the lattice parameter c decreases as the doping level x increases. The compounds exhibited a paramagnetic to ferromagnetic transition at temperatures of about 170, 125 K for the x = 1 and 0.75 samples, respectively. The temperature dependence of resistivity for the samples can be well fitted by the 2D variable hoping (VRH) model rho = rho(o) exp(T-0/T)(1/3) (where rho(o) is a material specific characteristic conductance, with unit Omega(-1), T-0 is a material specific characteristic temperature in K) over the whole measured temperature range. First principles calculations indicated that the Nd doped Sr2CoO4 compounds show high spin polarization. (C) 2012 American Institute of Physics. [doi:10.1063/1.3672825

Ferroelectric and mutiferroic study of bismuth ferrite from the viewpoint of materials science

Ferroelectric and mutiferroic materials have been studied from the viewpoint of pure and applied physics. For the applications, a study from the viewpoint of materials science will be important in the future. Examples of materials science study are substitution of elements, selection of substrate in thin films and in-situ observation. Nano-scale domain configurations of multiferroic BiFeO3 thin films and their dynamic response to the externally applied fields have been investigated by piezoresponse force microscopy. High-resolution piezoresponse images reveal that nano-scale domain walls are approximately with ~2 nm in width. In this article, we focus on BiFeO3 as mutiferroic materials and as ferroelectric materials. We will present our results about electric and magnetic properties, and scanning probe microscopy observations. Local polarization reversal and retention behavior will also be presented and discussed

Mixed Odor Classification for QCM Sensor Data by Neural Network

Normal 0 21 false false false EN-US JA X-NONE &#13; /* Style Definitions */&#13; table.MsoNormalTable&#13; {mso-style-name:"Tabla normal";&#13; mso-tstyle-rowband-size:0;&#13; mso-tstyle-colband-size:0;&#13; mso-style-noshow:yes;&#13; mso-style-priority:99;&#13; mso-style-parent:"";&#13; mso-padding-alt:0cm 5.4pt 0cm 5.4pt;&#13; mso-para-margin:0cm;&#13; mso-para-margin-bottom:.0001pt;&#13; mso-pagination:widow-orphan;&#13; font-size:12.0pt;&#13; font-family:Cambria;&#13; mso-ascii-font-family:Cambria;&#13; mso-ascii-theme-font:minor-latin;&#13; mso-hansi-font-family:Cambria;&#13; mso-hansi-theme-font:minor-latin;&#13; mso-ansi-language:EN-US;}&#13; Compared with metal oxide semiconductor gas sensors, quarts crystal microbalance (QCM) sensors are sensitive for odors. Using an array of QCM sensors, we measure mixed odors and classify them into an original odor class before mixing based on neural networks. For simplicity we consider the case that two kinds of odor are mixed since more than two becomes too complex to analyze the classification results. We have used eight sensors and four kinds of odor are used as the original odors. The neural network used here is a conventional layered neural network. The classification is acceptable although the perfect classification could not been achieved. <!--EndFragment--