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91.
Eu2+-doped BaSi6N8O phosphors (Ba1−xEuxSi6N8O, 0.005≤x≤0.2) were synthesized by gas-pressure sintering of the powder mixture of BaCO3, Si3N4, and Eu2O3 at 1750 °C under 0.5 MPa N2. The fired powder consists of a major BaSi6N8O phase and a trace amount of impurity phases. The structural result of the BaSi6N8O powder, refined by the Rietveld method, agrees well with that of single crystals. A wide blue luminescence band peaking at about 500 nm is observed in BaSi6N8O:Eu2+, upon excitation with the ultraviolet light of 310 nm. Although Eu is covalently bonded to six nearest neighbor nitrogen atoms, the luminescence of Eu2+ is not significantly redshifted but shows a very narrow excitation spectrum at high energies. The origin of the short-wavelength luminescence is mainly ascribed to a small crystal-field splitting as a result of extremely long distances between europium and nitrogen ligands in BaSi6N8O:Eu2+. 相似文献
92.
A unified theory of the anomalous Hall effect (AHE) is presented for multiband ferromagnetic metals with dilute impurities. In the clean limit, the AHE is mostly due to extrinsic skew scattering. When the Fermi level is located around anticrossing of band dispersions split by spin-orbit interaction, the intrinsic AHE to be calculated ab initio is resonantly enhanced by its nonperturbative nature, revealing the extrinsic-to-intrinsic crossover which occurs when the relaxation rate is comparable to the spin-orbit coupling. 相似文献
93.
Yutaka Udagawa Masatake Yamaguchi Tomohito Tsuru Hiroaki Abe Naoto Sekimura 《哲学杂志》2013,93(12):1665-1678
We have investigated the effects of Sn and Nb on dislocation properties in a Zr lattice to elucidate the role of these alloying elements in hydride nucleation processes. According to experimental observations, γ-hydride habit planes are close to the prismatic plane in pure Zr and close to the basal plane in Zircaloy. Dislocation loops are observed around hydride precipitates, implying they play a part in hydride formation. Our ab initio generalized stacking-fault energy calculations showed remarkable effects of Sn on unstable-stacking energy and stacking-fault energy: these parameters for basal slip were considerably reduced while those for prismatic slip were increased in the presence of Sn. These results suggest selective stabilization and enhancement of dislocation spreading in the basal plane, promoting possible elementary processes of hydride precipitation with basal habit plane, i.e. screw-dislocation spreading and edge-dislocation emission in the basal plane. 相似文献
94.
A dinaphtho[2,3-b:2′,3′-i]dihydrophenazine (DNP) derivative was synthesized by Buchwald-Hartwig cross-coupling, and its electronic spectrum was compared with that of dinaphtho[b,i]dihydrophenazine-5,18-dione (DNP-dione) as an anthraquinone analog. An absorption band of DNP is attributed to extension of π-conjugation over the entire molecule via the N atom. DNP-dione showed a broad absorption band in the range 450–490?nm due to intramolecular charge-transfer interactions. Additionally, the absolute fluorescence quantum yield of DNP was larger than that of DNP-dione. DNP-dione exhibited reversible oxidation peaks and a similar oxidation potential to DNP, since there are very weak electronic interactions between the anthracene and anthraquinone units across the N atoms with the 4-octyloxyphenyl substituent. 相似文献
95.
We demonstrated the spectrally narrowed laser emission from all-plastic organic waveguide with the distributed feedback (DFB) resonator pumped by Ti-sapphire femtosecond laser. We fabricated the DFB resonator on a surface of a photoresist polymer using an interference of laser beams. All-plastic waveguide with organic dyes dispersed in poly(N-vinylcarbazole) and polystyrene matrix was spin-coated on a DFB resonator. Very narrow full width at half maximum (FWHM) of 0.15 nm in emission wavelength was observed, whereas an excitation laser of Ti-sapphire femtosecond laser has broad FWHM of 14 nm. 相似文献
96.
Journal of Statistical Physics - We investigate the fundamental relation between entropy production rate and the speed of energy exchange between a system and baths in classical Markov processes.... 相似文献
97.
Frontispiece: An Optically and Thermally Switchable Electronic Structure Based on an Anthracene–BODIPY Conjugate
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98.
RhIII-Catalyzed Double Dehydrogenative Coupling of Free 1-Naphthylamines with α,β-Unsaturated Esters
Dr. Supriya Rej Prof. Dr. Naoto Chatani 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(49):11093-11098
The RhIII-catalyzed, consecutive double C−H oxidative coupling of free 1-naphthylamine and α,β-unsaturated esters through C−H/C−H and C−H/N−H bonds is reported. The one step reaction leads to the formation of biologically important alkylidene-1,2-dihydrobenzo[cd]indoles scaffolds. This efficient process is much more synthetically convenient and useful than others because the starting materials, such as 1-naphthylamine derivatives are readily available and the free amine serves as a directing group. 相似文献
99.
Synthesis of conjugated polymers possessing diketopyrrolopyrrole units bearing phenyl,pyridyl, and thiazolyl groups by direct arylation polycondensation: Effects of aromatic groups in DPP on physical properties
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Junpei Kuwabara Naoto Takase Takeshi Yasuda Takaki Kanbara 《Journal of polymer science. Part A, Polymer chemistry》2016,54(15):2337-2345
Conjugated polymers containing phenyl‐, pyridyl‐, and thiazolyl‐flanked diketopyrrolopyrrole (DPP) were synthesized by direct arylation polycondensation of 3,4‐ethylenedioxythiophene derivatives and dibrominated DPP‐based monomers, in order to probe the effects of the aromatic groups in the DPP units on the absorption property, energy level, and crystallinity. A polymer possessing thiazolyl‐flanked DPP units was found to display long‐wavelength absorption properties and higher crystallinity than the polymers bearing phenyl‐ and pyridyl‐flanked DPP units. These features of the thiazolyl‐based polymer were afforded by its coplanar structure of the main chain. The synthesized polymers showed semiconducting properties in organic field effect transistors and organic photovoltaics. Direct arylation polycondensation is an efficient synthetic method that affords a series of DPP‐based polymers in a simple fashion and, thus, helping in a comprehensive understanding on the relationship between the aromatic groups in DPP units and their physical properties. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2337–2345 相似文献
100.
Naoto Sato Taiki Hayashi Kazuma Tochigi Prof. Hiroaki Wada Prof. Atsushi Shimojima Prof. Kazuyuki Kuroda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(33):7860-7865
Eight corners of a double-four ring cage-type germanoxane, containing a fluoride ion, were successfully silylated by the combination of chlorosilanes and silazanes. Three different silyl groups, trimethylsilyl, dimethylsilyl, and dimethylvinylsilyl, were attached on the corners of germanoxane cage. The solubility and reactivity of the cage modified with dimethylvinylsilyl groups were significantly increased, allowing for further reaction. Hydrosilylation reaction between dimethylvinylsilylated cage geramanoxanes and dimethylsilylated cage siloxanes afforded porous solids. Functionalization of the corners of germanoxanes with silyl groups should provide valuable building blocks in various functional materials. 相似文献