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Preparation Route (preparation + route)
Selected AbstractsInfluence of the preparation route on the optical properties of dosimetric phosphors based on rare-earth doped polycrystalline strontium boratesCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2004A. Lavat Abstract Most of commercial dosimetric phosphors consist of suitably doped polycrystalline compounds. Whereas the activation issue has been usually addressed, less attention has been paid to the influence of host preparation in the final perfomance of the products. In this paper different routes have been followed to synthesise phosphors based on rare-earth doped strontium borates. The structural and optical properties of the materials have been given special consideration. Finally, thermoluminescence glow curves have been recorded in order to assess which of the preparation routes yields the most efficient compound. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A Simple and Innovative Route to Prepare a Novel Carbon Nanotube/Prussian Blue Electrode and its Utilization as a Highly Sensitive H2O2 Amperometric SensorADVANCED FUNCTIONAL MATERIALS, Issue 24 2009Edson Nossol Abstract The utilization of iron-based species (mainly metallic iron, hematite and magnetite) encapsulated into multi-walled carbon nanotubes (CNTs) as reactants in an electrochemical synthesis is reported for the first time in this work. Prussian blue (PB) is electrosynthesized in a heterogeneous reaction between ferricyanide ions in aqueous solution and the iron-species encapsulated into CNTs, resulting in novel CNT/PB paste electrodes. This innovative preparation route produces an intimate contact between the PB and the CNTs, which improves the stability and redox properties of PB. The PB formation and the chemical interaction between the PB and the CNTs are confirmed by Raman spectroscopy. The electrode is employed as a hydrogen peroxide amperometric sensor, resulting in a very low limit of detection (1.94,×,10,8,mol L,1) and very high sensitivity (15.3,A cm,2M,1). [source] Influence of Point-Defect Reaction Kinetics on the Lattice Parameter of Ce0.8Gd0.2O1.9ADVANCED FUNCTIONAL MATERIALS, Issue 4 2009Anna Kossoy Abstract The kinetics of point-defect association/dissociation reactions in Ce0.8Gd0.2O1.9 and their influence on the crystal lattice parameter are investigated by monitoring thermally induced stress and strain in substrate- and self-supported thin films. It is found that, in the temperature range of 100,180,°C, the lattice parameter of the substrate-supported films and the lateral dimensions of annealed, self-supported films both exhibit a hysteretic behavior consistent with dissociation/association of oxygen vacancy,aliovalent dopant complexes. This leads to strong deviation from linear elastic behavior, denoted in the authors' previous work as the "chemical strain" effect. At room temperature, the equilibrium state of the point defects is reached within a few months. During this period, the lattice parameter of the substrate-supported films spontaneously increases, while the self-supported films are observed to transform from the flat to the buckled state, indicating that formation of the dopant,vacancy complex is associated with a volume increase. The unexpectedly slow kinetics of establishing the defect equilibrium at room temperature can explain the fact that, depending on the sample history, the "observable" lattice parameters of Ce0.8Gd0.2O1.9, as reported in the literature, may differ from one another by a few tenths of a percent. These findings strongly suggest that the lattice parameter of the materials with a large concentration of interacting point defects is a strong function of time and material preparation route. [source] Synthesis of bulk MgB2 superconductors by pulsed electric currentAICHE JOURNAL, Issue 7 2006A. M. Locci Abstract A preparation method to simultaneously synthesize and consolidate bulk MgB2 superconductors from Mg and B commercial elemental powders by means of the spark plasma sintering technique is reported. The influence of process parameters on sintering process dynamics as well as product characteristics, determined by transport and magnetic measurements, is investigated. The superconducting properties of the obtained samples, and particularly the critical current density, are comparable or better than those corresponding to other MgB2 preparation techniques. Thus, the superconductive properties of the bulk MgB2 materials synthesized in this work are suitable for selected applications, such as magnetic levitation, magnetic screening, and fault current limiters. It should be finally noted that the proposed method represents a particularly rapid preparation route as compared to other techniques. © 2006 American Institute of Chemical Engineers AIChE J, 2006 [source] Crystallographic Orientation of Y2Ba4CuMOx (M=Nb, Zr, Ag) Nanoparticles Embedded in Bulk, Melt-Textured YBCO Studied by EBSDJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2007A. Koblischka-Veneva Crystallographic orientations of Y,Ba,Cu,O (YBCO) and embedded Y2Ba4CuMOx (M=Nb, Zr, Ag) nanoparticles in bulk, melt-textured YBCO samples are studied by electron backscatter diffraction. Y2BaCuO5 particles exhibit no preferred orientation but have a strong negative influence on the matrix orientation. In contrast, the nanoparticles do not disturb the texture of the YBCO matrix. Depending on the preparation route, a different particle orientation with respect to the matrix is obtained. Untextured nanoparticles are formed by solid-state reaction during the melt process by adding oxides (Nb2O5 or Y2O3) to the precursor powder. Preformed Y2Ba4CuMOx particles added to the precursor in the form of prereacted nanopowder exhibit a dominant single orientation related to the surrounding YBCO matrix. [source] Preparing Low-Loss Low-Temperature Cofired Ceramic Material without Glass AdditionJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2000Heli Jantunen A low-temperature cofired ceramic (LTCC) composition for radio-frequency purposes was accomplished without prior glass preparation. In this process, the formulation was made by mixing the glass-forming oxides (ZnO, SiO2, and B2O3) with the commercial microwave ceramic MgTiO3,CaTiO3. The sintering, microstructure, and microwave properties were compared to a formulation with exactly the same composition, but a conventional production route, including glass preparation. The novel preparation route resulted in improved firing properties of the mixture. Also, the densities, porosities, and phases of the samples were almost the same as those of the conventional samples, but the phase fractions were different. Finally, this preparation route produced better dielectric values. [source] On the use of Cu catalysts for tailoring carbon nanostructures in alcohol-CVDPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11-12 2009Ewa Borowiak-Palen Abstract The use of the alcohol-chemical vapor deposition (A-CVD) process applying ferromagnetic catalyst mixes is a powerful technique for the synthesis of high purity single-, double- and multiwalled carbon nanotubes (MWCNTs). Here, we report on a systematic experimental study on the preparation route of carbon nanofibres (CNFs), bamboo-like carbon nanotubes (BMCNTs) with defined pocket size and mean diameter and MWCNTs. Copper serves as the catalyst. The morphology of the samples is controlled by the reaction temperature and the catalyst loading relative to the support content (MgO). A detailed analysis of the samples was achieved by electron transmission microscopy observations and Raman spectroscopy. Schematic illustration showing the carbon nanostructure evolution with increasing reaction temperature. [source] Influence of the preparation route on the optical properties of dosimetric phosphors based on rare-earth doped polycrystalline strontium boratesCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2004A. Lavat Abstract Most of commercial dosimetric phosphors consist of suitably doped polycrystalline compounds. Whereas the activation issue has been usually addressed, less attention has been paid to the influence of host preparation in the final perfomance of the products. In this paper different routes have been followed to synthesise phosphors based on rare-earth doped strontium borates. The structural and optical properties of the materials have been given special consideration. Finally, thermoluminescence glow curves have been recorded in order to assess which of the preparation routes yields the most efficient compound. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Proceedings of the 2nd International Conference on Semiconductor Quantum Dots (QD2002)PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2003Y. Arakawa The International Conference on Semiconductor Quantum Dots (QD2002) was held at Komaba Campus of University of Tokyo, Japan, from Monday, 30 September, through Thursday, 3 October 2002. The purpose of the QD2002 was to bring together scientists from different fields of physics and chemistry to discuss topics of common interest and significance in such growing areas including semiconductor quantum dots, nanocrystals, and clusters. The conference was focused on the optical and electronic properties of three-dimensionally confined nanostructures grown both by epitaxial methods and chemical preparation routes. The QD2002 was the second in a series which started in Munich, Germany, in 2000. The scope of the QD2002 covered various research fields including novel fabrication techniques of nanoheterostructures, electronic structures, optical properties, electronic properties/single electron tunneling processes, molecular dots, nanocrystals, device applications such as lasers and memories, coherent processes/quantum computations, and biomedical applications. [source] | |||||||||||||