bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optical Limiting Processes in Derivatized Fullerenes and Porphyrins/Phthalocyanines
Authors: Kohlman R. , Klimov V. , Shi X. , Grigorova M. , Mattes B. R. , McBranch D. , Wang H. , Wudl F. , Nogués J.-L. , Moreshead W. 
Published: April 2011

AbstractWe review our results from spectral studies of the ultrafast excited-state absorption in fullerenes and derivatized fullerenes. These results allow determination of both the spectral response of reverse saturable absorption (RSA) nonlinearities such as optical limiting (OL) in fullerenes, and the dynamical response for different morphologies. We have investigated the effects of thin film and various sol-gel glass environments on the nanosecond OL and femtosecond dynamics of derivatized fullerenes. These data provide evidence of decay pathways which compete with the intersystem crossing to a triplet from the initial singlet states. With appropriate processing, however, the OL response of derivatized-fullerene sol-gel glasses can be enhanced to approach that of the same molecule in solution, while significantly enhancing the optical damage threshold. The optical limiting of these derivatized fullerenes is compared with that of various porphyrin and phthalocyanine molecules.
Solvato-Controlled Doping of Conducting Polymers: Enhanced Stabilty in Silver-Triflate Doped Films
Authors: Lauritzen Michael V. , Holdcroft Steven 
Published: April 2011

AbstractStable, conductive films of poly(3-alkylthiophenes) (P3ATs) can be obtained from a single chloroform based solution containing polymer, oxidant (silver triflate), and an oxidantcoordinating ligand (pyridine). Casting of this solution, followed by evaporation of the ligand, results in an electronically conductive film which is more stable and, notably, in the case of thick films, is free of the cracking which often results from swelling of the films during the doping process. This technique, coined solvato-controlled oxidative doping, results in films possessing enhanced stability compared to those oxidized by conventional dopants such as ferric chloride. Also, these silver-containing films are much more stable than those electrochemically doped with the triflate anion. Thus, the presence of metallic silver in the doped film has a profound effect on the stability of the conducting form.
Melt Processed Electrically Conductive Binary and Ternary Immiscible Polymer / Polyaniline Blends
Authors: Zilberman M. , Siegmann A. , Narkis M. 
Published: April 2011

AbstractIn the present study, conductive binary and ternary blends of PANI with thermoplastic polymers were prepared by melt processing.The binary blends' investigation focused on the morphology and on the resulting electrical conductivity. Generally, the level of interaction between the doped PANI and the matrix polymer determines the blend morphology, and thus, its electrical conductivity. The morphology of a conductive network is described by a primary structure of small dispersed polyaniline particles, interconnected by secondary short range fine fibrillar structure. In blends containing a semicrystalline matrix the doped PANI network locates within the amorphous regions, leading to a reduction of the percolation concentration.The ternary blends' investigation focused on a system containing two co-continuous immiscible thermoplastic polymers and PANI. The PANI is preferably located in one of the matrix polymers. This concentration effect enables high electrical conductivities at low PANI contents.
Determination of the Internal Electric Field in the Electrooptic Active Layer of Multilayer Polymer Stacks
Authors: Grossmann S. , Weyrauch T. , Haase W. 
Published: April 2011

AbstractWe report on a method to investigate the inhomogeneous distribution of an electric dc field in multilayer polymer stacks. In situ electroabsorption (EA) measurements are applied in order to estimate the local electric fields in double layer polymer films. The observed time dependent behaviour is compared with a model equivalent circuit. The results indicate that besides the relation of ohmic resistivities and capacities of the different polymer layers in the investigated systems also the influence of the electric properties of polymer/electrode and polymer/polymer interfaces must be considered.
Magnetic Properties of Organic Ferromagnetic TDAE-C60 Single Crystals and Thin Films
Authors: Tokumoto M. , Tsubaki Y. , Pokhodnya K. , sakakibara Y. , Omerzu A. , Mihailovic D. , Uchida T. 
Published: April 2011

AbstractRecent progress in the study on magnetic properties of molecular soft ferromagnet TDAE-C60 (where TDAE is tetrakis(dimethylamino) ethylene) is reported. Both crystalline and thin film samples are prepared by the diffusion method and the temperature and field dependence of magnetization are studied by SQUID magnetometer. The magnetic behaviors of single crystals were found to vary from sample to sample. In best single crystals, the saturation magnetization as high as 1.0 μB/C60 has been observed. Spontaneous magnetization and its temperature dependence was evaluated from the Arrott plot. The ferromagnetic phase transition was also observed in TDAE-C60 thin films.
Effect of Impurity Ions and Permanent Dipoles for Device Performance of Thin-Film Electroluminescent Diodes
Authors: Tsutsui Tetsuo , Yahiro Masayuki , Zou Dechun 
Published: April 2011

AbstractDouble-layer EL diodes composed of a spin-coated Polyvinylcarbazole (PVCz) layer and a vacuum-sublimed tris-(8-hydroxyquinoline)aluminum (Alq) layer were prepared. The diodes with the same device structure but with PVCz layer with added ionic impurities were also prepared. The diodes were driven at constant voltage and allowed to stand under short-circuit or reverse bias conditions. Observations of luminance-current density-voltage relations at constant voltage driving were repeated. The decrease of both luminance and current density during constant voltage driving were observed. Both spontaneous and reverse-bias assisted recovery of device performances were observed and these degradation and recovery phenomena were discussed in terms of the movement of ionic impurities in organic layers.
Corrosion Protection of Metals by Conductive Polymers III. Improved Performance and Inhibition in NaCl
Authors: Lu Wei-Kang , Elsenbaumer Ronald L. , Chen T. , Kulkarni V. G. 
Published: April 2011

AbstractThe use of conducting polymers for corrosion prevention is an area which has gained increasing attention during the last decade [1]. This study explores the use of polyaniline based polymer coatings for corrosion prevention on mild steel. Data on coating degradation and passivation on electrochemically polarized painted metal specimens exposed to acid chloride solutions and artificial seawater at an ambient temperature are presented. A Systematic comparison between controls and designated coated sample sets has been made to demonstrate good corrosion protection efficiency with synergistic effects between conductive polymers and metals by classical DC monitoring techniques. Brief comparisons are made with data from simulated marine exposure. Meanwhile, in separate experiments, electrochemical data were obtained for conductive polymer primer coatings with epoxy top-coat under fully immersed conditions by using electrochemical noise (ECN) monitoring and scanning electrochemical microscopy (SECM) techniques to discover the initial localized corrosion phenomena in order to achieve further understanding of the protection mechanism. Additionally, electrochemical impedance (EIS) spectra were utilized for the assessment of anti-corrosion performance provided by conducting polymers to mild steel.
Magnetic Field Effect in Highly Pure, Highly Fluorescent Conjugated Polymers
Authors: Graupner W. , Sacher M. , Graupner M. , Zenz C. , Grampp G. , Hermetter A. , Leising G. 
Published: April 2011

AbstractWe report on the magnetic field effect (MFE) on the photoluminescence in films of a highly fluorescent conjugated laddertype poly(paraphenylene) (LPPP). We observe no MFE for the pure material, however, the introduction of a very small content of chemical defects via photo-oxidation leads to a MFE proportional to the amount of defects. The chemically induced increase in MFE is correlated with a change in other properties of the LPPP films, such as photoluminescence emission and excitation spectra, transient photoluminescence and infrared spectra.
Design, Methodology and Preparation of Novel Polymers for Nonlinear Optics
Authors: Chittibabu K. G. , Li L. , Balasubramanian S. , Wang X. , Sukwattanasinitt M. , Yang K. , Kumar J. , Sandman D. J. , Tripathy S. K. 
Published: April 2011

AbstractOne-pot post-polymerization modification reactions such as azo-coupling and tricyanovinylation reactions were employed to synthesize a series of polymers containing different nonlinear optical (NLO) chromophoric as well as ionic functionalities. We have extended and established the versatility of our earlier reported post-modification strategy to incorporate various heteroaromatic chromophores as well as ionic functionalities in the polymers, at the final stage of synthesis. The correlation between different heteroaromatic chromophore structures and the NLO properties of the polymers was extensively studied. Polymers containing heteroaromatic chromophores exhibit improved temporal stability and enhanced NLO activity. Polymers with ionic chromophores were employed to fabricate NLO active ultra-thin films using electrostatic selfassembling (ESA) technique. Attempts were also made to synthesize second order NLO active polydiacetylene derivatives using post azo-coupling reaction.
Synthesis of High-Tg Azo Polymer and the Optimization of its Poling Condition for Stable EO System
Authors: Fukuda Takashi , Matsuda Hiro , Shiraga Takao , Kato Masao , Nakanishi Hachiro 
Published: April 2011

AbstractA new material for second-order nonlinear optics was synthesized, which was a copolymer of N-phenylmaleimide, 4-isopropenylphenol and 4'-[N-ethyl-N-(4-isopropenylphenoxyethyl) amino]-4”-nitroazobenzene (PMPD). PMPD films were poled by corona-poling technique. The optical nonlinearity of poled PMPD was measured by second harmonic generation (SHG) and electro-optic (EO) effect, and it was demonstrated that this polymer had large optical nonlinearity and a very long-time stability, as was expected. These properties were thought to be sufficient enough for practical EO devices. On the other hand, from the viewpoint of the sample preparation technique, poling conditions were investigated in order to achieve the highest possible dipolar orientation. As a result, it was found that the relationship between the electric resistance of polymer film and substrate was a critical factor for corona-poling efficiency. From a simple model, it was suggested that the poled PMPD film prepared onto the glass substrate with a resistance of ˜0.8 GΩ (at 160 °C) exhibits large SHG and EO coefficients, more than ˜500 × 10−9 e.s.u (d33 at λ = 1.064 μm) and ˜70 pm/V(r33 at λ = 632.8 nm), respectively. It should be noted that this expected values are approximately twice as much as obtained under conventional corona-poling conditions.
Pressure Dependence of Photoluminescence of Oligothiophenes
Authors: Rossi L. , Graupner W. , Resel R. , Meghdadi F. , Leising G. , Sannicolo' F. , Benincori T. , Lanzani G. , Tubino R. 
Published: April 2011

AbstractWe report on the nature of emitting states in two different quaterthiophenes: the unsubstituted quaterthiophenes (T4) and a bridged T4 (T4B), where the bridging have been realized by introducing a second bond between the two central thiophene rings. The effect of the chemical bridging on the photophysics of these compounds have been studied via photoluminescence measurements under hydrostatic pressure, which permit to clarify the influence of interchain coupling, conformational effects and intrachain structural changes on the optical properties.
Thermally stable iridescent colors of a new low-molecular-weight cholesteric compound in the solid state and the application to fullcolor recording
Authors: Tamaoki Nobuyuki , Parfenov Alexander V. , Masaki Atsushi , Matsuda Hiro 
Published: April 2011

AbstractWe synthesized a series of new di-cholesteryl esters of several diacids. One of the compounds containing both of a diyne unit and long alkylene units, in the form of a thin solid film, showed stable iridescent colours in the visible region after rapid cooling process from the temperature of the cholesteric liquid crystalline phase. Measurement of selective reflectance of visible light, X-ray diffraction, optical rotation dispersion of the solid films proved that the films remained the cholesteric ordering of the molecules. The cholesteric structure in the solid films were completely stable at room temperature. The colour of the solid film was totally, partially or in imagewise manner changed into selected colours by adjusting the temperature of the surface just before the rapid cooling process. The property of this compound can be applicable to memory media with high density using the spectrum of light, or to thermosensitive full-colour recording materials.
Composition and Electrode Effects on the Electrical Properties of SrBi2Ta2O9
Authors: Thomas Darin T. , Fujimura Norifumi , Streiffer S. K. , Kingon Angus I. 
Published: April 2011

AbstractSrBi2Ta2O9 has attracted great interest for non-volatile memory applications due to its minimal polarization fatigue. This paper describes systematic studies, using pulsed laser deposition, on the effect of deposition conditions on the Bi-Pt reaction and on the potential for low temperature processing. Changing the deposition temperature (Ts) and oxygen gas pressure during deposition can control the Bi content in the films. At a Ts of 600°C, the films have excess Bi and do not fully crystallize to SBT, resulting in poor remnant polarization (Pr). These films consist mostly of the pyrochlore phase, plus a small amount of disordered, c-oriented layered perovskite SBT. By annealing over 750°C, the films show improved Pr, but further Pt - Bi interactions occur. At a Ts of 700°C, the as-deposited films are fully crystallized and show saturated hysteresis loops. However, Bi deficiency through alloying results in reduced remnant polarization (2Pr = 7.0μC/cm2). Films on Ir/Pt show reduced electrode reactions and improved properties.
Domain Structures of Epitaxial SrRuO3 Thin Films
Authors: Jiang J. C. , Pan X. , Chen C. L. 
Published: April 2011

ABSTRACTThe structural characteristics of SrRuO3 thin films deposited on a (001) SrTiO3 substrate by pulsed laser were studied by transmission electron microscopy (TEM) and high-resolution TEM. TEM studies of cross-sectional specimens revealed the epitaxial growth of the films with the SrRuO3-(110) plane parallel to the SrTiO3-(001) plane. Two types of 90° rotational domain structures were observed in both cross-sectional and plan-viewing specimens. The in-plane orientations of these domains with respect to the substrate are either of SrRuO3-[110] // SrTiO3 - [100] and SrRuO3-[001] // SrTiO3-[010], or of SrRuO3-[110] // SrTiO3-[010] and SrRuO3-[001] // SrTiO3-[100].
Ferroelectric Thin Films of Bi-Containing Layered Perovskites
Authors: Du Xiaofeng , Chen I-Wei 
Published: April 2011

ABSTRACTFerroelectric thin films of Bi-containing layered perovskites such as Bi4Ti3O12, PbBi2Nb2O9 and SrBi2Nb2O9 have been processed by metal-organic decomposition (MOD) method. Films with random or c-orientation have been obtained via different heat treatment. Nucleation control has been identified as the mechanism for the texture evolution in these films. A strong polarization anisotropy has been observed which corresponds to the layered polarization in the crystal structure. The fatigue test results show that Ti seems to be a common species that exists in fatigue-prone ferroelectrics.
Phase Transition and Pyroelectric Properties of La-Modified PbTiO3 Thin Films
Authors: Iijima Kenji , Niihara Koichi 
Published: April 2011

ABSTRACTPhase transition and related electric properties of La-modified PbTiO3 (PLT) thin films were investigated. Curie temperature of the films decreased and the diffuseness of the phase transition increased with increasing La content. Simultaneously, it was losing a ferroelectricity and pyroelectric properties degraded in La-rich region. This is considered to be due to the increase of a defect in the film by exchanging Pb2+ ions to La3+ ions. Compensation of the defect by the addition of Mn ion improve the ferroelectricity of the PLT and the films showed an extremely large pyroelectric properties.
Domain Wall Pinning by Grain Boundaries During Electric Field Poling of KNbO3 Thin Films
Authors: Gopalan Venkatraman , Raj Rishi 
Published: April 2011

ABSTRACTWe present evidence for grain-boundary pinning of domain walls as controlling the electric field poling behavior of KNbO3 thin films. Two epitaxial film systems are compared: (I) film on MgO (100) substrate with KNbO3 (110)// 120Å SrTiO3 (100) //MgO(lOO) and (II) film on SrTiO3 (100) substrate with KNbO3 (110)// SrTiO3 (100). Quantitative measurement of the area fractions of four domain variants in each film system was made using in-situ second harmonic generation measurement while applying an external electric field at room temperature. While the film system (I) showed reversible domain wall motion, the film system (II) snowed some permanent poling after the removal of the external field. Transmission Electron Microscopy revealed a network of low angle grain boundaries of ∼ 1.5–2° misorientation along the substrate cubic axes in the growth plane of the film system (I) and also a network of 6° and 120° walls intersecting these grain boundaries at 45° in the film growth plane. These features were found to be absent in the film system (II). We propose that the observed electric field poling phenomena is due to the pinning of 60° and 120° domain walls by low angle grain boundaries.
Ferroelectric Properties and Crystal Structure of YBa2Cu3O7/BaxSr(1−x)TiO3 Heterostructures
Authors: Schwan CH. , Martin F. , Jakob G. , Martinez J. C. , Adrian H. 
Published: April 2011

ABSTRACTEpitaxial YBa2Cu3O7/Ba0.5Sr0.5TiO3 (YBCO/BST) and YBCO/BaTiO3 (BTO) heterostructures were prepared by dc and rf sputtering on SrTiO3 and MgO substrates. The YBCO/BTO bilayers exhibit an inductive superconducting transition temperature of 85 K and the ferroelectric phase transition of BST shows a Curie-Weiss temperature of 310 K. Microstructure was investigated by x-ray-diffraction and atomic force microscopy. In this work we also studied the insulator's conductivity and the contribution of domain walls to permittivity.
Preparation of Boron Nitride Thin Films by MOCVD
Authors: Lee Sang-Yeol , Jin Yong-Gi , Nam Young-Woo , Lee Joong Kee , Park Dalkeun 
Published: April 2011

ABSTRACTBoron nitride thin films were prepared on Si(100) substrate by CVD. Triethylboron and ammonia were employed as precursors and various operating parameters such as reactor pressure, temperature, feed rates of gases were varied to investigate their effects on deposition rate and film characteristics. Total gas pressure in the reactor was varied from atmospheric to I torr. Deposition temperature was in the range 850 – 1,050 °C. Deposition rate increased with partial pressure of TEB but decreased with total pressure in the reactor. Deposited films were examined with SEM, FTIR, XPS, AES, XRD. Prepared films were BN of turbostratic structure.
Chemically Prepared Lead Magnesium Niobate Dielectrics
Authors: Tuttle B. A. , Voigt J. A. , Sipola D. L. , Olson W. R. , Goy D. M. 
Published: April 2011

ABSTRACTA chemical solution powder synthesis technique has been developed that produces fine, uniform powders of lead magnesium niobate (PMN) with 60 to 80 nm crystallite size. The synthesis technique was based on the dissolution of lead acetate and alkoxide precursors in acetic acid followed by precipitation with oxalic acid/propanol solutions. Lead magnesium niobate ceramics fabricated from these chemically derived powders had smaller, more uniform grain size and higher dielectric constants than ceramics fabricated from mixed oxide powders that were processed under similar thermal conditions. Chem-prep PMN dielectrics with peak dielectric constants greater than 22,000 and polarizations in excess of 29 μC/cm2 were obtained for 1100°C firing treatments. Substantial decreases in dielectric constant and polarization were measured for chemically prepared PMN ceramics fired at lower temperatures, consistent with previous work on mixed oxide materials.
Low-Temperature, Solution-Based Routes to Nanocrystalline InS Powders and Thin Films
Authors: Hollingsworth Jennifer A. , Buhro William E. 
Published: April 2011

ABSTRACTWe have developed several solution-based preparations for nanocrystalline orthorhombic InS, which is a mid band gap semiconductor (2.44 eV) with potential applications in photovoltaics. Various reagents were used as indium (t-Bu3In, t-Bu2InCl) and sulfur (H2S, (TMS)2S) sources. Growth of crystalline powders was dependent upon the addition or in-situ generation of indium metal. These reactions represent the first reported use of a Solution-Liquid-Solid (SLS) mechanism by which semiconductors are grown from a molten metal flux for a system other than the III-V family of semiconductors. The studies on powder preparations were used to develop a new, low-temperature (185 °C) chemical-bath process for depositing a polycrystalline InS thin film. The film was deposited from a solution of t-Bu3In and elemental sulfur onto an indium-coated fused-silica substrate; the indium film acted as the crystallization medium.
Room Temperature Phase-Selective Synthesis of Metastable Lead Chromium Oxides
Authors: Doxsee Kenneth M. , Jang Meehae 
Published: April 2011

ABSTRACTThe salt metathesis reaction between lead(II) salts and potassium chromate in methanolic solution, mediated by the formation of a soluble complex of potassium chromate with a cyclic polyether, affords orthorhombic PbCrO4rather than the monoclinic modification formed in aqueous solution. When the aqueous metathesis reaction is carried out in the presence of tertiary amines, a lead oxide-rich phase, PbO•PbCrO4(Pb2CrO5), is selectively formed.
Metal-Organic Chemical Vapor Deposition Routes to Films of Transparent Conducting Oxides
Authors: Wang A. , Cheng S. C. , Belot J. A. , Mcneely R. J. , Cheng J. , Marcordes B. , Marks T. J. , Dai J. Y. , Chang R.P.H. , Schindler J. L. , Chudzik M.P. , Kannewurf C. R. 
Published: April 2011

ABSTRACTThis contribution reports the in situ growth of transparent, conducting GaxIn2-xO3 and ZnkIn2Ok+3 films by MOCVD (metal-organic chemical vapor deposition) techniques using In(dpm)3, Ga(dpm)3, and Zn(dpm)2 (dpm = dipivaloylmethanate) as volatile precursors. In the former series, film microstructure in the x = 0.4 – 1.0 range is predominantly cubic with 25° C electrical conductivities as high as 1300 S/cm (n-type; carrier density = 1.2 × 1020 cm−3, mobility = 68 cm2/Vs) and optical transparency in the visible region greater than that of ITO. In the latter series, films in the composition range K = 0.16 – 3.60 were studied; the microstructural systematics are rather complex. Electrical conductivities (25° C) as high as 1000 S/cm (n-type; carrier density = 3.7 × 1020 cm−3, mobility = 18.6 cm2/Vs) for K = 0.66 were measured. The optical transparency window is significantly broader than that of ITO.