Advanced Materials

Cover image for Advanced Materials

1997

Volume 9, Issue 13

Pages fmi–fmi, 1006–1072

  1. Masthead

    1. Top of page
    2. Masthead
    3. Materials Forum
    4. Editorial
    5. Reviews
    6. Communications
    7. Research News
    8. Book Reviews
    1. Masthead (page fmi)

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970091301

  2. Materials Forum

    1. Top of page
    2. Masthead
    3. Materials Forum
    4. Editorial
    5. Reviews
    6. Communications
    7. Research News
    8. Book Reviews
    1. Materials Forum (page 1006)

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970091302

  3. Editorial

    1. Top of page
    2. Masthead
    3. Materials Forum
    4. Editorial
    5. Reviews
    6. Communications
    7. Research News
    8. Book Reviews
    1. You have free access to this content
      18 — a sign of maturity? (page 1007)

      Deborah Hollis

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970091303

  4. Reviews

    1. Top of page
    2. Masthead
    3. Materials Forum
    4. Editorial
    5. Reviews
    6. Communications
    7. Research News
    8. Book Reviews
    1. Giant magnetoresistance, charge-ordering, and related aspects of manganates and other oxide systems (pages 1009–1017)

      Prof. C. N. R. Rao and Prof. Anthony K. Cheetham

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970091304

      Giant magnetoresistance, and spin-, charge-, and orbital-ordering are some of the properties displayed by manganates that make these materials of interest in magnetic recording, sensor, and actuator technology. New and significant results on the giant magnetoresistance found in films as well as polycrystalline and single-crystal samples of rare earth manganates are reviewed along with related aspects. The unique features of these systems and the as-yet unsolved problems are highlighted. Charge-ordering as opposed to spin-ordering is also discussed and suggestions for future directions are given.

    2. Self-Organized Quantum Wires and Dots in III – V semiconductors (pages 1019–1026)

      Prof. Hajime Asahi

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970091305

      The fabrication of quantum wires and quantum dots in III–V semiconductors using self-organization phenomena is reviewed. The Stranski–Krastanov (S-K) mode growth, step-bunching, and strain-induced lateral composition modulation techniques are covered. The Figure shows the vertical stacking of islands that are formed by the alternate S-K mode growth of five cycles of an In(Ga) quantum dot layer and a GaAs spacer layer.

  5. Communications

    1. Top of page
    2. Masthead
    3. Materials Forum
    4. Editorial
    5. Reviews
    6. Communications
    7. Research News
    8. Book Reviews
    1. Photo-oxidation of poly(p-phenylenevinylene) (pages 1027–1031)

      Dr. Kezhao Z. Xing, Dr. Nicklas Johansson, Dr. Graham Beamson, Dr. David T. Clark, Prof. Jean-Luc Brédas and Prof. William R. Salaneck

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970091306

      The operating lifetime of light-emitting devices (LEDs) based on poly(p-phenylenevinylene) (PPV), one of the most widely used conjugated polymers for polymer-based LEDs, is sensitive to air exposure. The effects associated with the photo-oxidation of PPV in air are examined. Possible photo-induced oxidation products are proposed based on simulations using stilbene as a model compound. X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and quantum-chemical calculations all indicate that a series of photo-oxidation products from on the surface of the PPV thin films.

    2. Low molecular weight and polymeric triphenylenes as hole transport materials in organic two-layer LEDs (pages 1031–1035)

      Andreas Bacher, Ingo Bleyl, Dr. Christian H. Erdelen, Prof. Dietrich Haarer, Dr. Wolfgang Paulus and Prof. Hans-Werner Schmidt

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970091307

      The benefits of using hexa-alkoxytriphenylenes as hole transport materials for two-layer light-emitting diodes are reported. Both low molecular weight and polymeric triphenylenes are investigated. The polyacrylate shown in the figure is demonstrated to have excellent film-forming properties and combines sufficient charge carrier mobility with good hole injection properties to make it a very suitable hole transport material.

    3. Highly polarized luminescence from oriented conjugated polymer/polyethylene blend films (pages 1035–1039)

      Dr. Christoph Weder, Christian Sarwa, Dr. Cees Bastiaansen and Prof. Paul Smith

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970091308

      Polarized photoluminescence (PL) from conjugated polymers has, in the past, attracted less attention than polarized electroluminescence (EL), despite possible applications in liquid crystal displays. A systematic investigation is presented of the structure–property relationships in oriented films of blends of different poly(2,5-dialkoxy-p-phenyleneethynylene)s with ultrahigh molecular weight polythylene, which exhibit highly polarized PL following gel processing and tensile deformation. Based on the experimental results, a new model is suggested for what occurs during orientation of the blends.

    4. Imaging polymers with supercritical carbon dioxide (pages 1039–1043)

      Prof. Christopher K. Ober, Dr. Allen H. Gabor, Dr. Paula Gallagher-Wetmore and Dr. Robert D. Allen

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970091309

      In lithographic techniques for forming nanostructures in surface and polymer thin films, the selectivity of the solvent becomes increasingly important as the target dimensions decrease. Polymer-based developers. The Figure shows the SC CO2–developed image of a copolymer of pentafluoroproyl methacrylate and tert-butyl methacrylate.

    5. Stability improvement of high-performance photorefractive polymers containing eutectic mixtures of electro-optic chromophores (pages 1043–1046)

      Dr. Klaus Meerholz, Reinhard Bittner, Yessica De Nardin, Prof. Christoph Bräuchle, Dr. Eric Hendrickx, Dr. Boris L. Volodin, Dr. Bernard Kippelen and Prof. Nasser Peyghambarian

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970091310

      Amorphous organic photorefractive materials, which are useful for reversible holographic applications such as real-time optical processing and holographic data storage, have excellent performance but limited self life, often owing to the crystallization of one of the components. A technique is presented for improving the long-term stability of composites based on poly(N-vinylcarbazole) that uses mixtures of two isomeric electrooptically active chromophores. The self-life is shown to be significantly increased and the photorefractive device performance as good as that of the best materials known previously.

    6. Solution-phase synthesis of luminescent materials libraries (pages 1046–1049)

      Xiao-Dong Sun, Dr. Kai-An Wang, Young Yoo, William G. Wallace-Freedman, Dr. Chen Gao, Dr. Xiao-Dong Xiang and Prof. Peter G. Schultz

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970091311

      The application of combinatorial methods to the synthesis and characterization of novel materials is described for the case of solution-phase synthesis of phosphors based on rare-earth-activated refractory metal oxides. A scanning multiinkjet system is shown to be suitable for the fabrication of a liberry such as (LamGd1-m)-AlnOx:Eumath image, the photoluminescence image of part of which is shown in the Figure.

    7. The thermal decomposition of an organometallic precursor for the preparation of YBa2Cu3O7−x (pages 1049–1052)

      Dr. Joachim R. Binder, Dr. Horst Wedemeyer and Prof. Hans Reuter

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970091312

      Why are the carrier densities of YBa2Cu3O7−x smaller in thin films prepared by wet-chemical methods than in those prepared by other methods? In order to answer this practically relevant question, the chemical reactions taking place need to be known exactly. The thermal decomposition of an organometallic precursor of YBa2Cu3O7−x—an important step in the wet-chemical preparation–has been investigated by the simultaneous application of dynamic and static characterization methods and the results are reported here.

    8. Novel N,N′-bridged dithiadiazafulvalene trapped in situ as a cation radical salt with polyoxometalate: (DTDAF)2Mo6O19 (pages 1052–1056)

      Nathalie Bellec, Dr. Dominique Lorcy, Prof. Albert Robert, Roger Carlier, Prof. André Tallec, Christian Rimbaud, Dr. Lahcène Ouahab, Rodolphe Clerac and Dr. Pierre Delhaes

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970091313

      A quasi-planar dithiadiazafulvalene (DTDAF) with high electrondonating properties is reported. The chemical synthesis of a phenyl-N,N′-bridged DTDAF (the Figure shows an ORTEP drawing of the DTDAF⊕⊙ cation radical) is described together with the preparation of a charge-transfer set by an situ trapping and investigations of teh structural and magnetic properties of this salt. Evidence for mixed valence states is presented.

    9. Molecular surface orientation field of a langmuir monolayer determined by second-harmonic microscopy (pages 1056–1060)

      Dr. Mathias Flörsheimer, Heiner Salmen, Martin Bösch, Christof Brillert, Maria Wierschem and Prof. Harald Fuchs

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970091314

      The characterization of a Langmuir monolayer at a water surface by means of second-harmonic microscopy (SHM) is reported. Details of the technique and the theory are presented in the following article. The application described here illustrates the main advantages of SHM: it provides quantitative information on the microscopic level and reveals additional information compared to linear microscopy techniques. It is demonstrated to open up new perspectives for the development and improvement of polar organic materials, starting from polar monolayers at an interface.

  6. Research News

    1. Top of page
    2. Masthead
    3. Materials Forum
    4. Editorial
    5. Reviews
    6. Communications
    7. Research News
    8. Book Reviews
    1. Second-harmonic microscopy — a quantitative probe for molecular surface order (pages 1061–1065)

      Dr. Mathias Flörsheimer, Martin Bösch, Christof Brillert, Maria Wierschem and Prof. Harald Fuchs

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970091315

      Second-harmonic microscopy—an application of which is presented in the previous article—is a fast quantitative technique for the imaging of interfaces such as that in the Figure. The theory of the technique, which is based on the generation of second-harmonic light specifically at surfaces or interfaces due to their lack of centrosymmetry, is outlined and the interpretation of the results discussed.

    2. Planar pore-filling — adsorption in porous silicon (pages 1067–1070)

      Dr. Robert B. Bjorklund, Shahin Zangooie and Prof. Hans Arwin

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19970091316

      Porous silicon has potential applications not only in optoelectronics but also in the areas of sensors and biomaterials. Research in this direction relies on the sorptive properties of the material, which means that fundamental adsorption studies are important. The various pore morphologies of porous silicon are reviewed, as are the types of experiments that have been performed related to adsorption from the gas and liquid phases, along with their results. It is suggested that three-dimensional surface-physics-oriented studies would lead to interesting insights.

  7. Book Reviews

    1. Top of page
    2. Masthead
    3. Materials Forum
    4. Editorial
    5. Reviews
    6. Communications
    7. Research News
    8. Book Reviews

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