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Single Crystals (single + crystal)
Kinds of Single Crystals Terms modified by Single Crystals Selected AbstractsBerichtigung: Strong Two-Photon Excited Fluorescence and Stimulated Emission from an Organic Single Crystal of an Oligo(Phenylene Vinylene)ANGEWANDTE CHEMIE, Issue 36 2010Fei Gao No abstract is available for this article. [source] Strong Two-Photon Excited Fluorescence and Stimulated Emission from an Organic Single Crystal of an Oligo(Phenylene Vinylene),ANGEWANDTE CHEMIE, Issue 4 2010Fei Gao Niedrig rein, hoch raus: Einkristalle eines Thiomethyl-terminierten Oligo(phenylenvinylens) zeigen einzigartige photonische Eigenschaften , einschließlich einer starken anisotropen Fluoreszenz (siehe optische und Fluoreszenzaufnahmen; Pfeil: Polarisationsrichtung), hoher Quantenausbeuten, großer Zweiphotonenabsorptionsquerschnitte und einer stimulierten Emission ,, die sie zu Kandidaten für optoelektronische Anwendungen wie Hochkonversionslaser machen. [source] ChemInform Abstract: Two Novel Zintl Compounds Na12Ge8Sn and Na15Ge8SnP: Single Crystal and Electronic Structures.CHEMINFORM, Issue 38 2008Yongkwan Dong Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Single Crystal of a Prussian Blue Analogue Based on Rubidium Manganese Hexacyanoferrate.CHEMINFORM, Issue 35 2007Hiroko Tokoro Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Structure and Spectra Character of Cobalt Nickel Sulfate Twelvehydrate (CNSH) Single Crystal.CHEMINFORM, Issue 7 2004Genbo Su Abstract For Abstract see ChemInform Abstract in Full Text. [source] Quenching the Hysteresis in Single Crystals of a 1D Chain Iron(II) Spin Crossover ComplexEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2008Birgit Weber Abstract The unusual grinding effects observed in the 1D spin crossover polymer [FeL(bipy)]n (1), with L being a tetradentate N2O22, coordinating Schiff base type ligand {(3,3,)-[1,2-phenylenebis(iminomethylidyne)]bis(2,4-pentanedionato)(2,)- N,N,,O2,O2,} and bipy = 4,4,-bipyridine, are investigated using magnetic measurements, X-ray powder diffraction and optical reflectivity studies. The observed behaviour can be explained when solvent effects are taken into account. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Czochralski-grown Single Crystals with Acentric Symmetry Group 32,ADVANCED ENGINEERING MATERIALS, Issue 7 2004R.B. Heimann Single crystals with calcium gallium germanate (Ca3Ga2Ge4O14, CGG) structure such as langasite La3Ga5SiO14 (LGS), its niobium (,langanite', La3Ga5.5Nb0.5O14, LGN) and tantalum (,langataite', La3Ga5.5Ta0.5O14, LGT) analogs as well as strontium niobium gallium silicate (Sr3NbGa3Si2O14, SNGS) and strontium tantalum gallium silicate (Sr3TaGa3Si2O14, STGS) were grown with high perfection by the Czochralski pulling technique. Specific electric conductivity, optical activity, and dielectric, piezoelectric, bulk and surface acoustic, elastic, and electro-optic properties were measured. [source] Organic Single Crystals: Azeotropic Binary Solvent Mixtures for Preparation of Organic Single Crystals (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 22 2009Mater. The inside cover of this issue illustrates the solution-phase self-assembly of organic single crystals by using azeotropic binary solvent mixtures, described by X. Li et al. on page 3610, and is a snap-shot taken during the self-assembly of tri-isopropylsilylethynyl pentacene single crystals from an azeotropic binary solvent mixture of isopropanol plus toluene, on a silicon substrate. These needle-like crystals were growing with time while floating in the bulk of the solution during solvent evaporation, with bright colors showing their birefringence. [source] Azeotropic Binary Solvent Mixtures for Preparation of Organic Single CrystalsADVANCED FUNCTIONAL MATERIALS, Issue 22 2009Xiaoran Li Abstract Here, a new approach is introduced to prepare large single crystals of ,-conjugated organic molecules from solution. Utilizing the concept of azeotropism, single crystals of tri-isopropylsilylethynyl pentacene (TIPS-PEN) with dimensions up to millimeters are facilely self-assembled from homogeneous solutions comprising two solvents with opposing polarities and a positive azeotropic point. At solvent compositions close to the azeotropic point, an abrupt transition of morphology from polycrystalline thin-films to large single crystals is found. How to adjust the initial ratio of the binary solvents so that the change in solvent composition during evaporation favors the specific H-aggregation and promotes an efficient self-assembly of TIPS-PEN is explained. The charge-carrier (hole) mobilities are substantially enhanced by a factor of 4 from the morphology of thin-films to large single crystals used as active layer in field-effect transistors. Additionally, this approach is extended to other ,,, stacked organic molecules to elucidate its broad applicability. [source] Silicon-Doped LiFePO4 Single Crystals: Growth, Conductivity Behavior, and DiffusivityADVANCED FUNCTIONAL MATERIALS, Issue 11 2009Ruhul Amin Abstract Single crystals of silicon doped LiFePO4 with a silicon content of 1% are grown successfully by the floating zone technique and characterized by single-crystal and powder X-ray diffraction, secondary ion mass spectroscopy, and chemical analysis. Electron paramagnetic resonance demonstrates the presence of only Fe2+; no traces of Fe3+ are found. Impedance spectroscopy as well as step-function polarization/depolarization (DC) measurements are carried out using the cells Ti/LiFe(Si)PO4/Ti and LiAl/LiI/LiFe(Si)PO4/LiI/LiAl. The electronic and ionic conductivities as well as the Li-diffusivity of the sample in the major crystallographic directions ([h00], [0k0], and [00l]) are determined. Within experimental error the transport properties along the b- and c-axes are found to be the same but differ significantly from the a-axis, which exhibits lower values. Compared to undoped LiFePO4, Si-doping leads to an increase of the ionic conductivity while the electronic conductivity decreases, which is in agreement with a donor effect. The activation energies of conductivities and diffusivities are interpreted in terms of defect chemistry and relevant Brouwer diagrams are given. [source] Light-Emitting Rubrene Nanowire Arrays: A Comparison with Rubrene Single CrystalsADVANCED FUNCTIONAL MATERIALS, Issue 5 2009Jin Woo Lee Abstract This is a report on a new method of growth of a light-emitting rubrene nanowires array with diameters of 200,±,10,nm by using organic vapor transport through Al2O3 nanoporous templates. Nanometer-scale laser confocal microscope (LCM) photoluminescence (PL) spectra and crystalline structures of the rubrene nanowires are compared with those of rubrene single crystals prepared with the same experimental conditions without the template. In the LCM PL spectra it is observed that the PL spectra and intensity varies with the detecting positions because of the crystal growth characteristics of the rubrene molecules. A single rubrene nanowire has a wider LCM PL band width than that of the rubrene single crystal. This may originate from the light emissions of the mixed polarized bands due to additional new crystallinity in the formation of the nanowires. From the current,voltage characteristic curves, the semiconducting nature of both the rubrene nanowires and single crystals is observed. [source] Field Emission and Cathodoluminescence of ZnS Hexagonal Pyramids of Zinc Blende Structured Single CrystalsADVANCED FUNCTIONAL MATERIALS, Issue 3 2009Zhi-Gang Chen Abstract Single-crystal hexagonal pyramids of zinc blende ZnS are fabricated by facile thermal evaporation in an ammonia atmosphere at 1150,°C. It is found that ZnS pyramids grow along the [111] crystal axis and possess a sharp tip with a diameter of ,10,nm and a micrometer-sized base. The structural model and growth mechanism are proposed based on crystallographic characteristics. This unique ZnS pyramid structure exhibits a low turn-on field (2.81,V µm,1), a high field-enhancement factor (over 3000), a large field-emission current density (20,mA cm,2), and good stability with very small fluctuation (0.9%). These superior field-emission properties are clearly attributed to the pyramid morphology, with micrometer-sized bases and nanotips, and high crystallinity. Moreover, a stable UV emission of 337,nm at room temperature is observed and can be ascribed to the band emission of the zinc blende phase. These results suggest that the ZnS hexagonal pyramids can be expected to find promising applications as field emitters and optoelectronic devices. [source] Probing the Anisotropic Field-Effect Mobility of Solution-Deposited Dicyclohexyl-,-quaterthiophene Single Crystals,ADVANCED FUNCTIONAL MATERIALS, Issue 10 2007Abstract Measuring the anisotropy of the field-effect mobility provides insight into the correlation between molecular packing and charge transport in organic semiconductor materials. Single-crystal field-effect transistors are ideal tools to study intrinsic charge transport because of their high crystalline order and chemical purity. The anisotropy of the field effect mobility in organic single crystals has previously been studied by lamination of macroscopically large single crystals onto device substrates. Here, a technique is presented that allows probing of the mobility anisotropy even though only small crystals are available. Crystals of a soluble oligothiophene derivative are grown in bromobenzene and drop-cast onto substrates containing arrays of bottom-contact gold electrodes. Mobility anisotropy curves are recorded by measuring numerous single crystal transistor devices. Surprisingly, two mobility maxima occur at azimuths corresponding to both axes of the rectangular cyclohexyl-substituted quaterthiophene (CH4T) in-plane unit cell, in contrast to the expected tensorial behavior of the field effect mobility. [source] Micrometer-Sized Organic Single Crystals, Anisotropic Transport, and Field-Effect Transistors of a Fused-Ring ThienoaceneADVANCED MATERIALS, Issue 44 2009Rongjin Li Hexagonal micrometer-sized organic single crystals of a fused-ring thienoacene are grown controllably by physical vapor transport over a large area. A "two-dimensional organic-ribbon mask" technique is developed to fabricate organic field-effect transistors based on an individual microcrystal. The accomplished transistors exhibit mobility as high as 1.8,cm2V,1s,1 with on/off ratios of typically >107. [source] Gyroid Single Crystals: Nanostructured Calcite Single Crystals with Gyroid Morphologies (Adv. Mater.ADVANCED MATERIALS, Issue 38-39 200939/2009) Single crystals typically assume a crystallographically distinct shape. Many biological organisms, however, synthesize single crystals with an intricate mescoscopic morphology that does not reflect the crystal symmetry. The cover shows a calcite single crystal with a bicontinuous gyroid morphology, which was obtained by calcite nucleation in a self-assembled polymer matrix in work reported by Ulli Steiner and co-workers on p. 3928. The characteristic size of the biomimetic structure is ,30 nm. The pattern in the title is the characteristic 211 plane of the gyroid morphology. [source] Nanostructured Calcite Single Crystals with Gyroid MorphologiesADVANCED MATERIALS, Issue 38-39 2009Alexander S. Finnemore Gyroid-structured calcite crystals are grown by templating though self-assembled copolymer films. The remarkable triply periodic minimal surface is perfectly replicated on the nanometer scale, while single crystallinity is maintained. This is a wholly synthetic route to a crystal morphology found in biological systems, only on a smaller length scale. [source] Calcite Growth in Hydrogels: Assessing the Mechanism of Polymer-Network Incorporation into Single CrystalsADVANCED MATERIALS, Issue 4 2009Hanying Li Calcite crystals grown in agarose hydrogels incorporate the gel network while retaining their single-crystal nature. The amount of gel network that is incorporated is determined by two competing factors: crystallization pressure promotes the exclusion of the gel network, while faster growth rates favor its incorporation. [source] Ordered Arrays of Nanopillars Formed by Photoelectrochemical Etching on Directly Imprinted TiO2 Single CrystalsADVANCED MATERIALS, Issue 2 2003H. Masuda Arrays of TiO2 nanopillars have been prepared by photochemically etching a TiO2 single crystal that had been previously imprinted with a corresponding array of dimples using SiC molds. The pillars have a high aspect ratio (see scanning electron microscopy (SEM) image in Figure) and the method is simple and suitable for high-throughput production. [source] Electrical Properties of Superlattice-Structured Bi4Ti3O12,PbBi4Ti4O15 Single CrystalsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2007M. Ikezaki Single crystals of superlattice-structured ferroelectrics composed of Bi4Ti3O12 and PbBi4Ti4O15 were grown and the properties of polarization hysteresis and leakage current along the a -axis were investigated. Oxidation treatment led to a marked increase in leakage current at room temperature, showing that electron hole acts as a detrimental carrier for electrical conduction. A well-developed polarization hysteresis with a remanent polarization of 41 ,C/cm2 was observed, which is suggested to originate from the peculiar ferroelectric displacement of Bi in the Bi2O2 layers. [source] High-Temperature Hydroxylation and Surface Corrosion of 2/1-Mullite Single Crystals in Water Vapor EnvironmentsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2006Nadine Eils 2/1-mullite single crystal (001) plates with thicknesses between 0.9 and 1.9 mm were exposed for 1.5, 3, 6, and 12 h at 1670°C to a slowly flowing (100 mL/min) water-rich gas mixture (O2/H2O 80/20). Under the given experimental conditions, 2/1-mullite yielded significant amounts of structurally bound OH groups across the bulk and decomposition of the crystal surface on a micrometer scale. Decomposition products are (i) sodium-containing silicon-rich alumino silicate glass formed from melt and (ii) ,-alumina, which crystallizes within melt cavities. The crystal plates that are free of any OH absorption before the corrosion experiments show a steep increase in OH absorption intensity up to 3 h of corrosion and a flattening toward longer times of exposure. The evaluation of OH intensity profiles implies an effective diffusion coefficient DH in the range between 1.5 and 2.5 × 10,7 cm2/s. [source] High-Temperature Tensile Strength of Er2O3 -Doped ZrO2 Single CrystalsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2006José Y. Pastor The deformation and fracture mechanisms in tension were studied in single-crystal Er2O3 -doped ZrO2 monofilaments processed by the laser-heated floating zone method. Tensile tests were carried out between 25° and 1400°C at different loading rates and the dominant deformation and fracture mechanisms were determined from the shape of the stress,strain curves, the morphology of the fracture surfaces, and the evidence provided by monofilaments deformed at high temperature and broken at ambient temperature. The tensile strength presented a minimum at 600°,800°C and it was controlled by the slow growth of a crack from the surface. This mechanism was also dominant in some monofilaments tested at 1000°C and above, while others showed extensive plastic deformation before fracture at these temperatures. The strength of plastically deformed monofilaments was significantly higher than those which failed by slow crack growth due to the marked strain hardening capacity of this material. [source] Effect of Uniaxial Stress Upon the Electromechanical Properties of Various Piezoelectric Ceramics and Single CrystalsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2006D. Viehland A systematic investigation of the stress-dependent (,) electromechanical properties of various ferroelectric ceramics and single crystals has been performed. Studies have been carried out on "hard" and "soft" piezoelectrics, electrostrictive ceramics, and various orientations of (1,x)Pb(Mg1/3Nb2/3)O3,(x) PbTiO3 PMN,x%PT single crystals. The large signal piezoelectric constant, acoustic power density, and coupling coefficient have been determined by calculation. The results are compared, in order to develop an understanding of the relative merits of the different types of active acoustic materials. [source] Secondary Ion Mass Spectroscopy Study of Oxygen-18 Tracer Diffusion in 2/1-Mullite Single CrystalsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2001Peter Fielitz Oxygen 18O tracer diffusion in Czochralski-grown mullite single crystals is investigated along [010] and [001]. Oxygen diffusion coefficients range between ,5 × 10,20 m2/s (1250°C) and ,9 × 10,18 m2/s (1525°C). The data does not show any significant anisotropy. The values of the activation enthalpy (4.5 eV) and of the activation entropy ((3.4 ± 1.6)kB, where kB is the Boltzmann constant) suggest that the atomic transport occurs via thermally activated vacancies. [source] Templated Grain Growth of Barium Titanate Single CrystalsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2000Paul W. Rehrig BaTiO3 single crystals were grown via templated grain growth (TGG), which is a process in which a single-crystal "template" is placed in contact with a sintered polycrystalline matrix and then heated to migrate the single-crystal boundary into the matrix. Millimeter-sized, stoichiometric single crystals of BaTiO3 were produced by heating polycrystalline matrix with a relative density of 97% and a Ba/Ti ratio of <1.00, which was bonded to a BaTiO3 single crystal, at temperatures above the eutectic temperature. Growth rates of 590,790, 180,350, and 42,59 ,m/h were observed for {111}-, {100}-, and {110}-oriented single-crystal templates, respectively. Lower-surface-energy facets were formed for {111}- and {100}-oriented templates, whereas {110} crystals maintained a {110} growth front, which indicated that this plane orientation was the lowest-energy surface in this system. SrTiO3 also was shown to be a suitable substrate for TGG of BaTiO3. [source] Comment on "Transport Properties of Tl5Te3 Single Crystals" [phys. stat. sol. (a) Vol.PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2007329 (2002)], No. Abstract Recently, Gamal et al. [phys. stat. sol. (a) 191, 322 (2002)] reported the results of electrical conductivity, Hall effect and thermoelectric power (TEP) measurements on Tl5Te3 single crystals. The samples used in the study were p-type semiconductors. From the experimental data for the temperature dependence of TEP, Gamal et al. determined the values of 1.6 × 10,41 kg and 1.5 × 10,40 kg, respectively, for the effective masses of electrons and holes in p-type Tl5Te3, which are about ten orders of magnitude smaller than the free electron mass, 9.11 × 10,31 kg. We argue that the anomalously small values obtained for the effective mass of charge carriers in Tl5Te3 have no physical significance. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Creep of Single Crystals , Modelling and Numerical AspectsPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2005Ivaylo Vladimirov A number of constitutive models, utilizing both microstructural and/or phenomenological considerations, have been developed for the simulation of the creep behaviour of nickel-base single crystal superalloys at elevated temperatures. In this work, emphasis is placed on the rate-dependent single crystal plasticity model [1]. A strategy for the identification of the material parameters of the model to fit the results from experiments has been implemented. The parameter fitting methodology rests upon a two-membered evolution strategy. In addition, a proposal is made for the extension of the Cailletaud model [1] by means of an evolution equation for a damage variable which enables the modelling of the tertiary creep stage. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Direct Formation of Mesoporous Coesite Single Crystals from Periodic Mesoporous Silica at Extreme Pressure,ANGEWANDTE CHEMIE, Issue 25 2010Paritosh Mohanty Dr. Unter extremem Druck, bei 12,GPa, gelingt die Titelreaktion ohne Templatzusatz. Aus SBA-16 entstehen so einkristalline Coesit-Partikel mit Porengrößen um 4,nm und ungefähr 50,% Porosität. Diese Reaktion lässt sich mit der kinetisch gesteuerten Kristallisation eines nichtporösen, elastisch verformten und glasartigen Siliciumdioxid-Intermediat erklären (siehe Schema). [source] ChemInform Abstract: Resistive Investigation of Pseudogap State in Non-stoichiometric LnBa2Cu3O7-, (Ln: Y, Ho) Single Crystals with Account for BCS,BEC Crossover.CHEMINFORM, Issue 1 2010R. V. Vovk Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: A Fast Low-Pressure Transport Route to Large Black Phosphorus Single Crystals.CHEMINFORM, Issue 47 2008Tom Nilges Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Magnetic Properties of U2Co17-xSix Single Crystals.CHEMINFORM, Issue 14 2008A. V. Andreev Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] | |||||||||||||||||||||||||||||||