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Room Temperature. (room + temperature)
Selected AbstractsThermoelectric properties of RE2,xMxCuO4 oxide sintering bulksELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 12 2008Yusuke Ichino Abstract La2,xSrxCuO4 (LSCO) and Sm2,xCexCuO4 (SCCO) polycrystal bulks with x=0 to 0.10 were made by solid-phase reaction method. From the X-ray diffraction patterns, LSCO and SCCO were confirmed single phase. Seebeck coefficient, resistivity, and heat conductivity decreased with increasing amount of Sr2+ and Ce2+ substitution. We estimated ZT from these values and found that the highest value of ZT=0.034 at 323 K was achieved in the LSCO with x=0.02. As a result, we conclude that LSCO and SCCO showed high thermoelectric properties around room temperature. We can expect RE2,xMxCuO4 will be a very useful material for thermoelectric module operating at room temperature. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 91(12): 24,28, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10003 [source] Long-Lived Luminescent Dendrimers with a [Ru(dpp)3]2+ -Type Core: Synthesis and Photophysical PropertiesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2009Uwe Hahn Abstract Metallodendrimers built around a [Ru(dpp)3]2+ -type core (dpp = 4,7-diphenyl-1,10-phenanthroline) were prepared containing peripheral phenyl moieties. The convergent synthesis of the ligands was accomplished by coupling dendritic branches with a focal amino function to the chelating phenanthroline precursor under the formation of sulfonamide linkages. Complexation of ruthenium ions afforded the corresponding metallodendrimers with up to 24 peripheral phenyl units in the case of the largest dendritic structure. The absorption spectra and luminescence properties of the four new dendrimers are reported. The dendritic effect is clearly visible, going from zero to second generation, as demonstrated by an elongation in the excited-state lifetime in aerated acetonitrile and improved emission quantum yields relative to the reference complex containing a [Ru(dpp)3]2+ core. Interestingly, the use of rigid and conjugated ruthenium-based cores results, for all dendritic structures, in luminescence lifetimes that are several microseconds long in deaerated solutions, even at room temperature.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Surfactant-Assisted Synthesis and Characterization of Novel Chain-Like CoNi Alloy AssembliesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 25 2007Lu-Ping Zhu Abstract Novel chain-like CoNi alloy assemblies with a length of up to 6,7 ,m were successfully prepared by a surfactant-assisted hydrothermal synthetic route at 100 °C for 2 h. The individual submicrospheres built from smaller CoNi nanoparticles had a diameter of about 400,500 nm. These microspheres were then integrated to form the novel chain-like CoNi alloy assemblies. The effects of synthetic parameters such as surfactant and solvent on the formation and morphology of CoNi samples were investigated. The experimental results showed that N2H4·H2O and CTA+ play important roles in the formation of the novel chain-like CoNi alloy assemblies. Based on the structural information provided by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, selected-area electron diffraction and energy-dispersive X-ray analysis, a growth mechanism was tentatively proposed for the formation of chain-like CoNi alloy assemblies. Magnetic hysteresis measurement revealed that the chain-like CoNi alloy assemblies display ferromagnetic behavior with a saturation magnetization of 96.15 emu/g and a coercivity of 144.75 Oe at room temperature. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Novel Cadmium(II) Adipate Coordination Polymers with Structural Transformation via Oxalate Ligand: Syntheses, Structures and Fluorescence PropertiesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 20 2004Na Hao Abstract Two novel cadmium adipate coordination polymers [Cd{O2C(CH2)4CO2}{1,10-phen}]n (1) and [Cd2(C2O4){O2C(CH2)4CO2(OH2)2}{2,2,-bipy}]·H2O (2) [adipic acid = HO2C(CH2)4CO2H] have been hydrothermally synthesized and characterized by elemental analyses, IR spectroscopy, thermogravimetric analysis and single-crystal X-ray diffraction. Crystallographic data for 1: monoclinic, C2/c, a = 16.186(3) Å, b = 15.487(3) Å, c = 14.052(3) Å, , = 112.73(3)°, Z = 8. Crystal data for 2: monoclinic, Cc, a = 23.448(5) Å, b = 11.826(2) Å, c = 8.3163(17) Å, , = 99.08(3)°, Z = 4. The structural analysis reveals that 1 forms a novel one-dimensional chain in which the binuclear Cd centers are linked by adipate anions. Compound 2 is the first example in which both a 2,2,-bipy ligand and an oxalate group are found in the {M/adipate} system. Compound 2 possesses one-dimensional sine- or cosine-type chains, which are alternately connected together by the oxalate group to form a three-dimensional framework. The structural determination reveals that the introduction of the oxalate ligand causes the dimensional transformation of the compounds. Compounds 1 and 2 show strong fluorescent properties at room temperature. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] The Electronic Structure of (Diiminopyridine)cobalt(I) ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 6 2004Quinten Knijnenburg Abstract DFT calculations show that square-planar LCoIR complexes of a diiminopyridine ligand are best regarded as containing low-spin CoII antiferromagnetically coupled to a ligand radical anion. The lowest triplet state, corresponding to a 3d,,* excitation, is calculated to be only a few kcal/mol above the ground state, and is thermally accessible. The anomalous 1H NMR chemical shifts of the LCoR complexes are suggested to be due to thermal population of the triplet state at room temperature. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Synthesis, Crystal Structure, and Photoluminescent Properties of a Tetracarbonyl(naphthyridylcarbamoyl)rhenium(I) Complex and a Highly Emissive Tetracarbonyl(naphthyridylamido)rhenium(I) ComplexEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2003Jing-Lin Zuo Abstract The reactions of Re(CO)5X (X = Cl, Br) with 7-amino-2,4-dimethyl-1,8-naphthyridine (H2L1) and 7-[2-(6-chloropyridyl)amino]-2,4-dimethyl-1,8-naphthyridine (HL2) in the presence of tBuOK afforded the ,1 -naphthyridylcarbamoyl complex [Re(CO)4(HL1CO)] (1) and the naphthyridylamido complex [Re(CO)4(L2)] (2), respectively. The structures of HL2, 1·CHCl3, 1·HL3·2CH2Cl2 [HL3 = (7-chloronaphthyridyl)(5,7-dimethylnaphthyridyl)amine], and 2 have been determined by X-ray crystallography. Complex 1 displays a weak emission at 453 nm in an EtOH/MeOH (1:4, v/v) glassy solution at 77 K; complex 2 exhibits an intense (quantum yield: 0.22 in CH2Cl2) and long-lived emission (46 ,s in CH2Cl2), with a solvent-sensitive ,max, in degassed solutions at room temperature. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2003) [source] Protonation of Diarylacetylenes in Superacid HSO3F and Their Oxidation in the HSO3F/PbO2 System: One-Pot Synthesis of Polysubstituted NaphthalenesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 27 2008Aleksander V. Vasilyev Abstract In the superacid HSO3F, diarylacetylenes bearing one electron-withdrawing group (NO2, CN, COMe, CO2Me) in each arene ring form stable ions, protonated at these groups. Oxidation of such diarylacetylenes in the HSO3F/PbO2 system at ,75 to ,50 °C over 2,2.5 h, followed by quenching of the reaction mixture with hydrochloric (or hydrobromic) acid at ,60 to 25 °C, resulted in the formation of (E,E)-1,4-dichloro (or dibromo)-1,2,3,4-tetraarylbuta-1,3-dienes. These butadienes spontaneously undergo electrocyclic transformation into polysubstituted naphthalenes at room temperature. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] A New Approach to the Synthesis of N,N -Dialkyladenine DerivativesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 29 2007M. José Alves Abstract N,N- Dialkyladenine derivatives were prepared by two different reaction sequences starting from 5-amino-4-cyanoformimidoylimidazoles. When these imidazoles were treated with dimethylformamide diethyl acetal, a 5-aminomethyleneamino-4-cyanoformimidoylimidazole was isolated and evolved to the N,N- dialkyladenine in the presence of a secondary alkylamine. The same purine structure was isolated when the 5-amino-4-cyanoformimidoylimidazole was first treated with a secondary amine to give a stable 4-amidino-5-aminoimidazole. The desired product was generated when the 4-amidino-5-aminoimidazole was combined with dimethylformamide diethyl acetal, at room temperature. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] N -Functionalization of Azoles through Coupling Reactions with Alkoxydienyl and Alkoxystyryl Boronic EstersEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 8 2007Annamaria Deagostino Abstract Alkoxydienyl boronates 1a and 1b and alkoxystyryl boronate 2 have been used in various copper mediated cross-coupling reactions with azoles. A variety of N -alkoxydienyl- and N -styrylazoles have been synthesized under mild conditions. The process utilizes Cu(OAc)2 in the presence of CsF in CH2Cl2 at room temperature. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Lithium Perchlorate-Catalyzed Three-Component Coupling: A Facile and General Method for the Synthesis of ,-Aminophosphonates under Solvent-Free ConditionsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 23 2003Najmedin Azizi Abstract A simple, efficient, and general method has been developed for the synthesis of ,-aminophosphonates in the presence of solid lithium perchlorate under solvent-free conditions. Thus secondary and tertiary ,-aminophosphonates were synthesized relatively quickly in good yields at room temperature. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] A modified and green methodology for preparation of polysubstituted furansHETEROATOM CHEMISTRY, Issue 4 2005Javad Azizian In this study, we introduced a very simple, one-pot and green methodology for preparation of polysubstituted furans by reaction of aromatic aldehydes, DMAD, and alkylisocyanides in water and at room temperature. © 2005 Wiley Periodicals, Inc. 16:259,262, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20086 [source] Ambient-temperature copper-catalyzed atom transfer radical polymerization of methacrylates in ethylene glycol solventsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 8 2005Solomon M. Kimani Abstract The use of ethylene glycol solvents in the room-temperature atom transfer radical polymerization (ATRP) of various hydrophobic and hydrophilic methacrylates is demonstrated. Unlike many of the very polar solvents described in the literature for room-temperature ATRP, these solvents have good solvency for a wide range of polymers and monomers and are cheap and relatively nontoxic. Ethylene glycols with one hydroxyl and one methoxy group, such as tri(ethylene glycol) monomethyl ether (TEGMME), provide optimal results. The polymerization of methyl methacrylate in TEGMME with CuBr/N,N,N,N,,N,-pentamethyldiethylenetriamine as the catalyst requires the addition of CuCl2 at the beginning of the reaction to produce well-controlled polymerizations. This leads to polymers with predictable molecular weights and relatively narrow polydispersities. Polymerization in solvents that are fully methoxy-capped terminate prematurely because of catalyst precipitation. The electrochemical behavior of copper complexes in selected solvents is examined to determine why these solvents provide good rates at room temperature. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1588,1598, 2005 [source] Microwave signal generation based on two single-longitudinal-mode erbium-doped fiber lasersMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 1 2010Jian-Hua Luo Abstract A simple microwave signal source is proposed by connecting two single-longitudinal-mode erbium-doped distributed Bragg reflector fiber lasers in series. For using same pump LD, mutual injection locking of two fiber lasers is achieved. The two single-longitudinal-mode lasers have 0.048 nm wavelength difference. By beating the two wavelengths at a photodetector, stable microwave signal at 6.17 GHz is achieved at room temperature. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 177,179, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24840 [source] Multiwavelength source based on SOA and EDFA in a ring-cavity resonatorMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 1 2009S. Shahi Abstract A multiwavelength source incorporating a semiconductor optical amplifier (SOA) and a erbium-doped fiber amplifier (EDFA) in a ring-cavity configuration was demonstrated. The multiwavelength source was able to generate more than 13 channels at ,27 dBm and above at a SOA bias current of 300 mA and 980-nm pump power of 92 mW. The number of wavelengths generated can be controlled by adjusting the birefringence of the ring cavity using the polarization controllers. The proposed laser has constant channel spacing of 0.8 nm, which is suitable for communication and sensing applications, and shows stable operation at room temperature. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 110,113, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23970 [source] Efficient multiwavelength linear cavity erbium-doped fiber laser over 1570,1600 nmMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2002Chun-Liu Zhao Abstract A simple and efficient L-band multiwavelength linear cavity fiber laser was obtained at room temperature by recycling detrimental 1550-nm band amplified spontaneous emission as a secondary pump source for the unpumped EDF section of fiber laser. The cavity was formed by two linear fiber loops. By changing the states of PCs inserted to fiber loops, stable dual- and tri-wavelength lasers with about 1-mW/channel were generated at room temperature. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 296,299, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10441 [source] Coherent phases and magnetoexcitons in graphenePHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2009Yu. E. Lozovik Abstract Unique band structure peculiarities of graphene imply that near Fermi level electrons are described by two-dimensional Dirac equation for massless particles. We investigate how these peculiarities manifest in electron,hole pairing and properties of indirect magnetoexcitons in two spatially separated, independently gated graphene layers. For electron,hole pairing, we derive asymptotical expressions for the gap in energy spectrum and discuss system behavior at various controlling parameters. We derive dispersion relations for magnetoexcitons and their effective-mass decompositions, and also discuss a possibility of magnetoexcitonic superfluidity. The systems under consideration can reveal coherent properties, dissipationless currents and Josephson phenomena at room temperature. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Characterization of the DNA-assisted purification of single-walled carbon nanotubesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2007G. Sánchez-Pomales Abstract Carbon nanotubes (CNTs) possess outstanding structural, mechanical, and electronic properties. Nevertheless, to achieve their full potential, many problems still need to be solved, including the development of an easy purification procedure, the design of functionalization chemistries that result in increased solubility of the CNTs without altering their properties, and the development of a simple route for the attachment of aligned CNTs on solid substrates. DNA offers a solution to the previous challenges. Recently, DNA-functionalized single-walled carbon nanotubes (SWNTs) have been prepared by our group and attached on gold by the self-assembling technique [1, 2]. We therefore decided to perform an in-depth study of the DNA-assisted functionalization of SWNTs, which leads to their purification. The results showed a decrease in the SWNTs impurities after functionalization with DNA and demonstrated that the method used is a straightforward and time-effective route for the purification of SWNTs at room temperature. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] MOVPE growth and optical characterization of GaAsN films with higher nitrogen concentrationsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2006F. Nakajima Abstract We have successfully grown high-N-content GaAsN films up to 5.1% on GaAs(001) substrates using tertiarybutylarsine (TBAs) as the As precursor by metalorganic vapour phase epitaxy (MOVPE). The narrow X-ray diffraction (XRD) peaks and clear Pendellosung fringes indicate that the GaAsN/GaAs interface is fairly flat and the GaAsN layers are uniform. By the photoluminescence (PL) measurement at 10 K, the clear PL peaks related to the near-band-edge transition could be detected and the bandgap energy was red-shifted to 1.16 eV in 1.9%-N GaAsN film. But, in higher N-content films no peak could be detected. So, post growth annealing in the reactor was applied to 4.7% and 5.1%-N films, and resulted in an enhancement of the PL peak intensity, and the bandgap energy of 5.1%-N film was consequently determined to be 0.95 eV at room temperature. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Room temperature electroluminescence from multilayer GeSi heterostructuresPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2006A. A. Tonkikh Abstract Details of silicon diodes with Ge/Si multilayer quantum dot heterostructures embedded in the Si p,n junction grown by molecular beam epitaxy emitting in the range of 1.4,1.7 µm at room temperature and continuous injection pumping are discussed. Output power of the light emitting diode reaches 1 µW/cm2 at applied current density of 2 A/cm2. Photoluminescence and transmission electron microscopy show that the origin of intense luminescence is defect free stacked Ge quantum dot array formed inside the structure. It is shown that doping by antimony improves structure quality and increases photoluminescence efficiency at room temperature. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Investigation of ZnTe thin films grown by Pulsed Laser Deposition methodPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 5 2007B. Kotlyarchuk Abstract This paper is devoted to optimization of the Pulsed Laser Deposition (PLD) growth condition of ZnTe films on various substrates and subsequent investigation of relevant parameters of growth process, structural, optical and electrical properties of grown films. Studies of the effect of growth parameters on the structural quality and properties of grown films were carried out. X-ray diffraction measurements showed that the ZnTe films, which have been deposited at optimal substrate temperatures, were characterized by a (111) preferred orientation with large average grain size. The optical transmission and reflectance in the energy range 1.5,5.5 eV for films grown at various substrate temperatures were measured. We calculated the variation in the absorption coefficient with the photon energy from the transmittance spectrum for samples grown at various substrate temperatures. Obtained data were analyzed and the value of the absorption coefficient, for allowed direct transitions, has been determined as a function of photon energy. We found that the undoped ZnTe films, which were grown by the PLD method, are typically p-type and possess resistivity in the range of 103 , cm at room temperature. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] GeSi/Si hetero-nanocrystals and the applications in MOSFET memoriesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2009Yi Shi Abstract Charge storage characteristics of MOSFET memory structure based on GeSi/Si hetero-nanocrystals (HNCs) are investigated by numerical simulation and experimental measurement. Owing to the advantages of a compound potential well and a higher offset at the valence band, this kind of memory has well hole storage. It is expected to serve as a high-performance nonvolatile memory operating at room temperature. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Spin-controlled optoelectronic devicesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2009S. Hövel Abstract We report on novel spin-optoelectronic devices which may transfer spintronics from the lab towards practical applications. Efficient spin-injection into light emitting diodes is provided by tunnelling through a MgO-barrier both at room temperature and without magnetic fields due to a special Fe/Tb-injector architecture. Furthermore, we show spin-amplification in lasers and finally a robust back conversion of polarised light into a spin-current by spin-filtering in a spin-detector, both working at room temperature. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Atmospheric-pressure MOVPE growth of In-rich InAlNPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008Y. Houchin Abstract This paper reports the atmospheric-pressure MOVPE growth of In-rich InAlN. All InAlN films prepared here (Al content:0, 0.43) do not show phase separation. The incorporation of Al in InAlN is decreased with increasing growth temperature. A decrease in Al content is also observed for films grown at a position farther from the up-stream end of the susceptor. The marked decrease in the Al content along the gas flow direction seems to be caused by the shortage of TMA supply at the downstream by the parasitic reaction of TMA. A single-crystalline InAlN film with an Al content of 0-0.43 is successfully grown by adjusting growth temperature and TMA/(TMI+TMA) molar ratio. FWHM of X-ray rocking curve for InAlN is increased with increasing Al content. The carrier concentrations in InAlN films are comparable to that in InN (1-5 × 1019 cm,3). All the single-crystalline InAlN films with an Al content of 0-0.3 show a photoluminescence at room temperature. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Nitride based nanotransistors as new sources and detectors of THz radiationsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008A. El Fatimy Abstract The plasma waves in gated two-dimensional electron gas have a linear dispersion law, similar to the sound waves. The transistor channel is acting as a resonator cavity for the plasma waves, which can reach frequencies in the Terahertz (THz) range for a sufficiently short gate length Field Effect Transistors (FETs). THz emission and detection by nanometer III-V transistors have been recently reported. In this work we report on THz emission and detection by nanometer GaN/AlGaN HEMTs. In particular, we show that specific GaN properties allow to observe THz emission up to room temperature. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Branching-induced spin polarization amplification in nonmagnetic semiconductorsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2006S.-W. Jung Abstract We study the spin injection in ferromagnet-tunnel barrier-semiconductor heterojunction structure embedded in the current-branching scheme. The current branching enables one to separately control the charge current from the spin current. As a result, it is possible to electrically control the spin current polarization within the semiconductor. Moreover, it can be enhanced further and may reach 100% by properly tuning the branched currents. Since the proposed scheme does not require low temperature operation, it may be a useful tool to generate the high spin current polarization at room temperature. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||||||||