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Terms modified by Transparent Selected AbstractsCorporate Governance in the Russian Federation: the relevance of the OECD Principles on shareholder rights and equitable treatmentCORPORATE GOVERNANCE, Issue 2 2001Fianna Jesover Despite progress in developing extensive legislation and regulations, there is still a long way to go before the standards of corporate governance in Russia will instil widespread confidence in investors. The emphasis is now on their implementation and enforcement by the state and private sector institutions. Transparent, equitable rules and predictable enforcement mechanisms are necessary to make the Russian economy attractive to both domestic and foreign investors, and enhance public confidence in the overall reform process. This paper uses the first two chapters of the OECD Principles of Corporate Governance on shareholder rights and their equitable treatment and looks through their prism at the Russian corporate governance condition. [source] Structural and microhardness studies of pure and thiourea doped glycine phosphite single crystalCRYSTAL RESEARCH AND TECHNOLOGY, Issue 7 2008R. Ezhil Vizhi Abstract Ferroelectric Glycine Phosphite (GPI) crystal have been grown from aqueous solution employing the slow cooling technique. As the crystal solubility in water depends on temperature, single crystals were grown. Transparent, colourless crystals with habit morphology weighing about 8g were obtained with in a month. The same procedure was used to grow single crystals of 10 wt% of Thiourea doped GPI (TUGPI). Formation of a new crystal was confirmed by Powder X-ray diffraction studies as well as FTIR studies. Crystalline quality were found using rocking curve for both the crystals. Due to the presence of Thiourea in TUGPI, it improves the crystalline perfection and also enhances the growth rate. The variation of hardness on (010) faces of monoclinic GPI and TUGPI crystals, with load were studied.Vickers hardness numbers, Hv were found to decrease with the increase in load. The value of Mayer's index, ,n ' was found to be greater than 1.6 for GPI and TUGPI showing soft-material category. The results are discussed in detail. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A Transparent, Flexible, Low-Temperature, and Solution-Processible Graphene Composite ElectrodeADVANCED FUNCTIONAL MATERIALS, Issue 17 2010Haixin Chang Abstract The synthesis and preparation of a new type of graphene composite material suitable for spin-coating into conductive, transparent, and flexible thin film electrodes in ambient conditions is reported here for the first time. Solution-processible graphene with diameter up to 50 ,m is synthesized by surfactant-assisted exfoliation of graphite oxide and in situ chemical reduction in a large quantity. Spin-coating the mixing solution of surfactant-functionalized graphene and PEDOT:PSS yields the graphene composite electrode (GCE) without the need for high temperature annealing, chemical vapor deposition, or any additional transfer-printing process. The conductivity and transparency of GCE are at the same level as those of an indium tin oxide (ITO) electrode. Importantly, it exhibits high stability (both mechanical and electrical) in bending tests of at least 1000 cycles. The performance of organic light-emitting diodes based on a GCE anode is comparable, if not superior, to that of OLEDs made with an ITO anode. [source] Flexible Silk,Inorganic Nanocomposites: From Transparent to Highly ReflectiveADVANCED FUNCTIONAL MATERIALS, Issue 5 2010Eugenia Kharlampieva Abstract A novel type of all-natural, biocompatible, and very robust nanoscale free-standing biohybrids are reported. They are obtained by integrating a silk fibroin matrix with functional inorganic nanoplatelets using a spin-assisted layer-by-layer assembly. The organized assembly of the silk fibroin with clay (montmorillonite) nanosheets results in highly transparent nanoscale films with significantly enhanced mechanical properties, including strength, toughness, and elastic modulus, as compared to those for the pristine silk nanomaterials. Moreover, replacing clay nanoplatelets with a highly reflective Langmuir monolayer of densely packed silver nanoplates causes a similar enhancement of the mechanical properties, but in contrast to the materials above, highly reflective, mirror-like, nanoscale flexible films are created. This strategy offers a new perspective for the fabrication of robust all-natural flexible nanocomposites with exceptional mechanical properties important for biomedical applications, such as reinforced tissue engineering. On the other hand, the ability to convert silk-based nanoscale films into mirror-like biocompatible flexible films can be intriguing for prospective photonics and optical exploitation of these nanobiohybrids. [source] Evolution of Electrical, Chemical, and Structural Properties of Transparent and Conducting Chemically Derived Graphene Thin FilmsADVANCED FUNCTIONAL MATERIALS, Issue 16 2009Cecilia Mattevi Abstract A detailed description of the electronic properties, chemical state, and structure of uniform single and few-layered graphene oxide (GO) thin films at different stages of reduction is reported. The residual oxygen content and structure of GO are monitored and these chemical and structural characteristics are correlated to electronic properties of the thin films at various stages of reduction. It is found that the electrical characteristics of reduced GO do not approach those of intrinsic graphene obtained by mechanical cleaving because the material remains significantly oxidized. The residual oxygen forms sp3 bonds with carbon atoms in the basal plane such that the carbon sp2 bonding fraction in fully reduced GO is ,0.80. The minority sp3 bonds disrupt the transport of carriers delocalized in the sp2 network, limiting the mobility, and conductivity of reduced GO thin films. Extrapolation of electrical conductivity data as a function of oxygen content reveals that complete removal of oxygen should lead to properties that are comparable to graphene. [source] Selectively Transparent and Conducting Photonic CrystalsADVANCED MATERIALS, Issue 5 2010Paul G. O'Brien Selectively transmissive and conductive 1D photonic crystals (PCs) are fabricated by alternately depositing sputtered ITO and spin-coated ATO nanoparticle films. These Bragg reflectors exhibit broad and intense Bragg peaks (tunable via the thickness of their ITO layers) over their stop gap but are highly transmissive over remaining spectral regions of the visible and infrared spectrum. [source] Reversible Luminescent Switching in a [Eu(SiW10MoO39)2]13, -Agarose Composite Film by Photosensitive Intramolecular Energy TransferADVANCED MATERIALS, Issue 17 2009Zhongliang Wang Transparent, flexible, self-supporting EuSiWMo/agarose composite films are fabricated by a combination of hydrogel chemistry and a casting technique, and present reversible, high-contrast luminescence photoswitching modulated by inorganic photochromic components through intramolecular resonance-energy transfer. Two-dimensional recording employing the luminescence as read-out signals is accomplished in this novel recording medium. [source] Transparent and Photo-stable ZnO Thin-film Transistors to Drive an Active Matrix Organic-Light- Emitting-Diode Display PanelADVANCED MATERIALS, Issue 6 2009Sang-Hee K. Park Transparent ZnO thin-film transistors (TFTs) with a defect-controlled channel and channel/dielectric interface maintain good photo-stability during device operation. The figure shows a cross-sectional view of a top-gate ZnO-based transparent TFT/storage capacitor cell structure, connected to front-panel organic-light-emitting-diode pixels to operate in bottom emission mode. [source] Waterborne, Nanocomposite Pressure-Sensitive Adhesives with High Tack Energy, Optical Transparency, and Electrical Conductivity,ADVANCED MATERIALS, Issue 20 2006T. Wang Transparent and conductive pressure-sensitive adhesives are cast from aqueous colloidal dispersions of poly(butyl acrylate) (P(BuA)) and functionalized carbon nanotubes (CNTs). At the percolation threshold for network formation (at only 0.3,wt,% functionalized CNT), the nanotubes remarkably double the amount of strain at adhesive failure and increase the adhesion energy by 85,% (see figure). The tack properties are explained by current models of adhesive debonding. [source] Synthesis, characterization, and comparison of properties of novel fluorinated poly(imide siloxane) copolymersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2008Anindita Ghosh Abstract Four new poly(imide siloxane) copolymers were prepared by a one-pot solution imidization method at a reaction temperature of 180°C in ortho -dichlorobenzene as a solvent. The polymers were made through the reaction of o -diphthaleic anhydride with four different diamines,4,4,-bis(p -aminophenoxy-3,3,-trifluoromethyl) terphenyl, 4,4,-bis(3,-trifluoromethyl- p -aminobiphenyl ether)biphenyl, 2,6-bis(3,-trifluoromethyl- p -aminobiphenyl ether)pyridine, and 2,5-bis(3,-trifluoromethyl- p -aminobiphenylether)thiopene,and aminopropyl-terminated poly dimethylsiloxane as a comonomer. The polymers were named 1a, 1b, 1c, and 1d, respectively. The synthesized polymers showed good solubility in different organic solvents. The resulting polymers were well characterized with gel permeation chromatography, IR, and NMR techniques. 1H-NMR indicated that the siloxane loading was about 36%, although 40 wt % was attempted. 29Si-NMR confirmed that the low siloxane incorporation was due to a disproportionation reaction of the siloxane chain that resulted in a lowering of the siloxane block length. The films of these polymers showed low water absorption of 0.02% and a low dielectric constant of 2.38 at 1 MHz. These polyimides showed good thermal stability with decomposition temperatures (5% weight loss) up to 460°C in nitrogen. Transparent, thin films of these poly(imide siloxane)s exhibited tensile strengths up to 30 MPa and elongations at break up to 103%, which depended on the structure of the repeating unit. The rheological properties showed ease of processability for these polymers with no change in the melt viscosity with the temperature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Preparation and properties of polyethoxysilsesquioxane-C60 hybridsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2007Takahiro Gunji Abstract Free-standing films of C60 -polyethoxysiloxane hybrids were prepared, and their optical limiting properties were evaluated. Triethoxysilylated C60, with a formula of H3C60[Si(OEt)3]3, was synthesized by the hydrolysilylation of C60 with triethoxysilane in the presence of platinum catalyst. C60 -polyethoxysiloxanes were prepared by a cohydrolytic polycondensation of triethoxysilylated C60 with tetraethoxysilane in a molar ratio of Si/C60 = 10,1000 under nitrogen flow. The molecular weight of C60 -polyethoxysiloxane increased with a decrease of Si/C60. Transparent and flexible free-standing films were prepared by aging an ethanol solution of C60 -polyethoxysiloxane at 80 °C for 6,8 days. The mechanical strength and Young's modulus increased with a decrease in Si/C60. These free-standing films showed an optical limiting property, for which the threshold value decreased from 1163 mJ/cm2 (Si/C60 = 1000) to 130 mJ/cm2 (Si/C60 = 10) with a decrease of Si/C60. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3273,3279, 2007 [source] Preparation of aromatic polyimides highly soluble in conventional solventsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 2 2002Wei Huang Abstract Several highly soluble polyimides were synthesized from various aromatic tetracarboxylic dianhydrides and an aromatic diamine containing tert -butyl pendent groups [4,4,-methylenebis(2- tert -butylaniline)]. All the polyimides showed excellent solubility in common solvents such as chloroform, tetrahydrofuran, and dioxane at room temperature. The number-average molecular weight ranged from 3.6 × 104 to 1.3 × 105 according to gel permeation chromatography relative to a polystyrene standard, and the polydispersity index was between 1.9 and 2.5. The glass-transition temperatures of the resulting polyimides ranged from 213 to 325 °C, as measured by differential scanning calorimetry, and little weight loss was observed up to 450 °C in N2 by thermogravimetric analysis. These experimental data indicated that the tert -butyl pendent groups reduced the interactions among polymer chains to improve their solubility in organic solvents without the loss of thermal stability. Transparent and flexible films of these polyimides were obtained via casting from solution. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 229,234, 2002 [source] Thiol-ene Hybrid Organic/Inorganic Nanostructured Coatings Based on Thiol-Functionalized Zirconium OxoclustersMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 23 2007Marco Sangermano Abstract The thiol-functionalized zirconium oxocluster Zr12(µ3 -O)8(µ3 -OH)8(MP)24,·,4MPA was used as inorganic nanosized building block in the thiol-ene photopolymerization of APE and TH in a 1:1 molar mixture. Transparent and crack-free coatings were obtained, and TEM analysis showed that the inorganic particles are well dispersed within the polymeric network with no significant macroscopic agglomeration. An increase of Tg values, storage modulus in the rubbery region, and thermal stability were evidenced by increasing the zirconium oxocluster content in the photocurable formulations. XPS analysis and SIMS depth profile were carried out on UV cured films and showed the presence of a homogeneously distributed zirconium oxocluster. [source] Transparent and Conductive Polyethylene Oxide Film by the Introduction of Individualized Single-Walled Carbon NanotubesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 24 2009Yong Chae Jung Abstract It is demonstrated that an optically transparent and electrically conductive polyethylene oxide (PEO) film is fabricated by the introduction of individualized single-walled carbon nanotubes (SWNTs). The incorporated SWNTs in the PEO film sustain their intrinsic electronic and optical properties and, in addition, the intrinsic properties of the polymer matrix are retained. The individualized SWNTs with smaller diameter provide high transmittance as well as good electrical conductivity in PEO films. [source] Preparation of Highly Transparent and Thermally Stable Films of , -Cyclodextrin/Polymer Inclusion ComplexesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 21 2007Takafumi Mori Abstract Films of an , -cyclodextrin/poly(, -caprolactone) inclusion complex have been successfully prepared and show high transparency and heat resistance in comparison to the pure polymer film. The physical properties, such as transparency, mechanical properties, and thermal stability, of the , -CD-PCL-IC films are found to depend on the , -cyclodextrin-to-polymer stoichiometry. [source] Protective organic-inorganic hybrid coatings on mild steel derived from Ti(OC4H9)4 -modified precursorsMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 9 2004V. Nguyen Abstract Titania-poly(methyl methacrylate-co-butyl methacrylate-co-methacrylic acid) hybrids prepared by a sol-gel method were deposited by dip coating on mild steel. Transparent and defect free coatings with titania content ranging between 0 and 12.7 wt.% have been prepared. Barrier properties and dry adherence have been tested by electrochemical impedance spectroscopy (EIS) and the vertical pull-off test, respectively. The pull-off test results suggest that the titanium alkoxide precursor must intercede on the substrate/coating interphase during film formation to create specific adhesive bondings with the substrate. In this paper, two capacitance models are used to estimate the water uptake, one based on a uniform and one on a heterogeneous distribution of sorbed water. Water uptake determined from these two models is compared to the gravimetry results. It is suggested that a reliable determination of the actual water uptake in coatings from capacitance measurements require an extensive experimental work. The variations in the state of sorbed water with the specimen type or immersion time, the leaching of organics during immersion or the slow diffusion of ions are fundamental factors that must be considered when comparing the water uptake determined from gravimetry and capacitance models. [source] Designed synthesis of nanostructured siloxane,organic hybrids from amphiphilic silicon-based precursorsTHE CHEMICAL RECORD, Issue 2 2006Atsushi Shimojima Abstract This paper reports on recent progress in the synthesis of nanostructured siloxane,organic hybrids based on the self-assembly of amphiphilic silicon-based precursors. A variety of ordered hybrid materials have been obtained by molecular design of the precursors. Alkoxysilanes and chlorosilanes with covalently attached hydrophobic organic tails are hydrolyzed to form amphiphilic molecules containing silanol groups, leading to the formation of layered (lamellar) structures. Transparent and oriented thin films of lamellar hybrids were prepared by the reaction in the presence of tetraalkoxysilane. In addition, the design of molecules having alkyl chains and large oligosiloxane heads led to the formation of mesophases consisting of cylindrical assemblies, providing a direct pathway to ordered porous silica. The synthesis, structural features, and formation processes of these hybrid mesostructures are discussed. © 2006 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 6: 53,63; 2006: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20073 [source] Synthesis of Transparent and Field-Responsive BaTiO3 Particle/Organosiloxane Hybrid FluidANGEWANDTE CHEMIE, Issue 29 2010Ken-ichi Mimura Transparent und homogen ist eine flüssige Lösung von BaTiO3 -Nanopartikeln (siehe Bild), die ihre rheologischen Eigenschaften beim Anlegen eines elektrischen Felds verändert. Unter Scherspannung (angedeutet durch den Pfeil) ordnen sich die Nanopartikel zu ausgerichteten Strukturen an, die durch konfokale 3D-Fluoreszenzmikroskopie erkennbar sind. (Weiße Punkte sind mit Fluorescein modifizierte Nanopartikel.) [source] Biologically Inspired, Strong, Transparent, and Functional Layered Organic,Inorganic Hybrid Films,ANGEWANDTE CHEMIE, Issue 12 2010Hong-Bin Yao Wie Mutter Natur: Biologisch inspirierte organisch-anorganische Hybridfilme, in denen Schichten aus Chitosan und Mikro- und Nanoplättchen aus Doppelhydroxiden mit Schichtstruktur abwechseln, ahmen die einzigartigen Mikroschichtstrukturen von Perlmutt nach (siehe Bild) und weisen eine hohe Reißfestigkeit auf. Zudem können die Hybridfilme mit den optischen Eigenschaften der Plättchen versehen werden. [source] ChemInform Abstract: Optically Transparent and Thermally Stable Nonlinear Optic Chromophores Featuring a Thieno[2,3-b]thiophene Donor.CHEMINFORM, Issue 1 2008Sabir H. Mashraqui 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] From Cloudy to Transparent: Chain Rearrangement in Hydrogen-Bonded Layer-by-Layer Assembled FilmsCHEMPHYSCHEM, Issue 3 2007Shuguang Yang Abstract The cloudiness of hydrogen-bonded LBL films assembled from polyvinylpyrrolidone (PVPON) and poly(acrylic acid) (PAA) is studied in detail by two approaches: spectroscopy (Fabry,Pérot fringes) and microscopy (AFM). Fabrication parameters such as temperature, molecular weight, pH value, and rinsing time, have notable influences on film cloudiness. The buildup of the PVPON/PAA film is a two-stage process of adsorption and chain rearrangement. Generally, adsorption is fast, while chain rearrangement is slow. The fast adsorption process traps defects, whereas the relatively slow chain-rearrangement process can not heal the defects in time; therefore, the number of defects continuously increases as LBL assembly proceeds, and a cloudy, heterogeneous film is produced. However, the as-prepared cloudy films become transparent and homogeneous on subsequent annealing in acidic water. UV/Vis spectroscopy and fluid AFM were applied to monitor this transition ex situ and in situ, respectively. It is found that increasing the annealing temperature accelerates the transition from cloudy to transparent, and the transition of the film made from higher molecular weight polymer is slower. [source] Toward replication in grids for digital libraries with freshness and correctness guaranteesCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 17 2008Fuat Akal Abstract Building digital libraries (DLs) on top of data grids while facilitating data access and minimizing access overheads is challenging. To achieve this, replication in a Grid has to provide dedicated features that are only partly supported by existing Grid environments. First, it must provide transparent and consistent access to distributed data. Second, it must dynamically control the creation and maintenance of replicas. Third, it should allow higher replication granularities, i.e. beyond individual files. Fourth, users should be able to specify their freshness demands, i.e. whether they need most recent data or are satisfied with slightly outdated data. Finally, all these tasks must be performed efficiently. This paper presents an approach that will finally allow one to build a fully integrated and self-managing replication subsystem for data grids that will provide all the above features. Our approach is to start with an accepted replication protocol for database clusters, namely PDBREP, and to adapt it to the grid. Copyright © 2008 John Wiley & Sons, Ltd. [source] User transparency: a fully sequential programming model for efficient data parallel image processingCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 6 2004F. J. Seinstra Abstract Although many image processing applications are ideally suited for parallel implementation, most researchers in imaging do not benefit from high-performance computing on a daily basis. Essentially, this is due to the fact that no parallelization tools exist that truly match the image processing researcher's frame of reference. As it is unrealistic to expect imaging researchers to become experts in parallel computing, tools must be provided to allow them to develop high-performance applications in a highly familiar manner. In an attempt to provide such a tool, we have designed a software architecture that allows transparent (i.e. sequential) implementation of data parallel imaging applications for execution on homogeneous distributed memory MIMD-style multicomputers. This paper presents an extensive overview of the design rationale behind the software architecture, and gives an assessment of the architecture's effectiveness in providing significant performance gains. In particular, we describe the implementation and automatic parallelization of three well-known example applications that contain many fundamental imaging operations: (1) template matching; (2) multi-baseline stereo vision; and (3) line detection. Based on experimental results we conclude that our software architecture constitutes a powerful and user-friendly tool for obtaining high performance in many important image processing research areas. Copyright © 2004 John Wiley & Sons, Ltd. [source] The integration of corporate governance in corporate social responsibility disclosuresCORPORATE SOCIAL RESPONSIBILITY AND ENVIRONMENTAL MANAGEMENT, Issue 1 2010Ans Kolk Abstract In recent years, not only has attention to corporate governance increased but also the notion has broadened considerably, and started to cover some aspects traditionally seen as being part of corporate social responsibility (CSR). CSR, corporate governance and their interlink seem particularly relevant for multinational enterprises (MNEs), which, due to their activities in multiple contexts around the world and concomitant visibility, generally face higher demands to be transparent and disclose information about such issues. Insights into whether and in which cases disclosures on the two topics actually merge has been very limited, however. This paper analyses to what extent corporate governance has become integrated in MNEs' disclosure practices on CSR. Based on an analysis of CSR reporting of Fortune Global 250 companies, findings show that more than half of them have a separate corporate governance section in their CSR report and/or explicitly link corporate governance and CSR issues. We also found that MNEs that disclose information on a wider variety of social and environmental issues and frame CSR with a focus on internal issues are more inclined to integrate corporate governance into their CSR reporting. This integration seems to be a global phenomenon that cuts across countries and sectors. Copyright © 2009 John Wiley & Sons, Ltd and ERP Environment. [source] Influence of the atmosphere on the growth of LiYF4 single crystal fibers by the micro-pulling-down methodCRYSTAL RESEARCH AND TECHNOLOGY, Issue 2 2009D. Maier Abstract Micro-pulling-down growth of LiYF4 single crystal fibers have been performed under different gas atmospheres using stoichiometric LiYF4 single crystal pieces from prior Czochralski experiments as starting material. Completely transparent and phase pure LiYF4 single crystal fibers could be obtained after evacuation of the recipient to 2×10 -6 mbar and subsequent filling with pure (99.995%) CF4 gas. Using a gas mixture of 5% CF4 in Argon or pure 5N Argon leads to the formation of micro crystallites of oxofluorides on the surface. Evacuating only to 3 × 10 -3 mbar leads, independently of atmosphere, to completely white fibers that are heavily contaminated with oxofluorides. DSC measurements of the completely transparent fiber grown under pure CF4 atmosphere reveal congruent melting behavior. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth of YCOB single crystals by flux technique and their characterizationCRYSTAL RESEARCH AND TECHNOLOGY, Issue 5 2008R. Arun Kumar Abstract Nonlinear optical single crystals of YCOB with good optical quality were grown by the flux technique for the first time. Polycrystalline YCOB samples were synthesized by solid state reaction method. The thermal analysis of the sample was performed with lithium carbonate flux in different weight proportions and the growth temperature was optimised. Single crystals of YCOB with dimensions 3 × 3 × 5 mm3 were obtained by the method of ,slow-cooling'. The grown crystals were characterized by XRD, UV-VIS-NIR, EDAX, FTIR and etching studies. The powder XRD pattern revealed the formation of YCOB compound. The lattice parameters were identified through single crystal XRD studies. The UV-VIS-NIR results showed that the crystal has a sharp cutoff at 220 nm and is nearly 55% transparent over a wide wavelength range enabling applications in the UV region. The EDAX measurement revealed the ,flux-free' crystal formation. The presence of the functional groups belonging to the YCOB crystals was identified by the FTIR results. ,Hillock-like' patterns are observed in the etching studies. The primary emphasis in this study is laid to describe ,flux technique' as an alternative method to grow YCOB crystals. The results are presented and discussed. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis and characterization of potassium magnesium sulphate hexahydrate crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2006M. Dhandapani Abstract Potassium magnesium sulphate hexahydrate (picromerite) was synthesized and single crystals were obtained from saturated aqueous solution by slow evaporation method at room temperature. The crystals were bright, colourless and transparent having well defined external faces. The grown crystals were characterized through Fourier Transform Infrared (FTIR) spectral studies and thermal analysis. The FTIR data were used to assign the characteristic vibrational frequencies of the various chemical bonds in the compound. The compound crystallizes in monoclinic lattice with the space group P21/c. The thermogravimetry (TG) indicates the removal of only two water molecules around 100 °C. A suitable decomposition pattern was formulated based on the percentage weight losses observed in TG of the compound. The results of differential thermal analysis (DTA) conform to the results of TGA. Differential scanning calorimetry (DSC) analysis carried out at high temperature suggests that the occurrence of two phase transitions in the crystal between 140 and 180 °C. When the crystal was cooled below the room temperature up to ,170 °C, no thermal anomaly was observed. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis, structural and thermal studies of tetrathioureacopper(I) chloride crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2005M. Dhandapani Abstract Tetrathioureacopper(I) chloride, hereafter abbreviated as TCC, was synthesised and single crystals were obtained from saturated aqueous solution by slow evaporation (solution growth) method at room temperature. The crystals obtained are bright, colourless and transparent having well defined external faces. The grown crystals were characterized through elemental analysis, single crystal X-ray diffraction study, thermal analysis, electron spin resonance spectroscopy and Fourier Transform infrared spectroscopy. The elemental analysis confirms the stoichiometry of the compound. The single crystal diffraction studies indicate that TCC crystallises in the tetragonal lattice and the unit cell parameters are a = b = 13.4082 Å, c = 13.8074 Å, V = 2482.29 Å3, , = , = , = 90°. Space group and the number of molecules per unit cell (Z) are found to be P41212 and 8 respectively. The TG curve of the sample shows a prolonged decomposition from 210 to 628.3 °C, from which the decomposition pattern has been formulated. The endothermic peaks in the DTA curve indicate melting and decomposition of the compound at 165.2 and 633.8 °C respectively. An exothermic peak in high temperature DSC indicates a phase transition in the compound at 274.8 °C. Thermal anomalies observed in the low temperature DSC at ,163.3, ,152.0, ,141.5, ,108.3, 1.0 and 12.1 °C in the heating run and ,157.1 and ,153.9 °C in the cooling run reveal first order phase transitions in the crystal. The peaks observed at ,146.2 °C in both the heating and cooling runs suggest occurrence of a second order phase transition in this compound. The IR spectroscopic data were used to assign the characteristic vibrational frequencies of various groups present in the compound. The ESR study confirms that the copper is in the +1 oxidation state in the complex. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth and characterization of LiCaGaF6CRYSTAL RESEARCH AND TECHNOLOGY, Issue 1-2 2005E. Sani Abstract Optically clear LiCaGaF6 (LiCGaF) single crystals up to 15 mm length were grown by the Czochralski method from CaF2 deficient melts. The substance melts incongruently at 751 °C. No significant deviations of the crystal composition from the nominal stoichiometry Li:Ca:Ga=1:1:1 could be found. X-ray structure analysis revealed that the substance crystallizes in the colquiriite type structure. LiCaGaF6 is transparent for optical wavelengths >140 , 150 nm. The thermal expansion of the trigonal crystals is ,11 = ,22 = 18.7×10 -6 K -1 perpendicular [001] and ,33 = 2.7×10 -6 K -1 parallel [001]. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth and characterization of La3Ga5.5Ta0.5O14 crystalCRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2004Haikuan Kong Abstract La3Ga5.5Ta0.5O14 (LGT) crystal was grown by using the Czochralski method. The as-grown crystal is transparent, free from inclusions and with no cracks. Specific heat, thermal expansion, dielectric constants, transmission spectrum and optical damage threshold of LGT have been measured, and the results show general properties of LGT are similar to that of La3Ga5SiO14 (LGS) crystal. The experiment to research the Q-switch properties of LGT has been performed and the results show LGT possesses smaller electrooptic coefficients than that of LGS and may not be an ideal material used as a Q-switch. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||