bluuebunny/crossref_metadata_2025_split huggingface dataset:
Conjugated Polymer Based Nanocomposites for Photonics Applications
Authors: Prasad P. N. , Kumar N. Deepak , Lal Manjari , Joshi Mukesh P. 
Published: April 2011

AbstractNanoscale synthesis and processing provides a novel approach for making a new generation of nanocomposite materials with exceptional optical and electrical properties that are needed for the development of new technologies. This presentation will focus on the preparation of nanocomposites made of Poly (para-phenylene vinylene) (PPV) with other polymers, inorganic glasses and semiconductors. We will present a new approach of nanoscale polymerization for making processable monodispersed oligomeric species of PPV which uses the base catalyzed polymerization of PPV monomer within the cavity of a reverse micelle nanoreactor. Application of this approach of fabricating novel materials for a variety of applications in photonics will also be discussed. In addition, we will discuss fabrication of bulk nanocomposites of PPV and silica by insitu polymerization of monomer within a porous glass and their lasing properties.
Electronic Structure and Optical Response of Electroluminescent Conjugated Polymers
Authors: Bredas J. L. , Cornil J. , Beljonne D. , Santos D. A. Dos , Shuaiv Z. , Silbey R. 
Published: April 2011

AbstractIn this contribution, we investigate by means of correlated quantum-chemical calculations the influence of intermolecular interactions on the absorption and emission properties of conjugated chains. Various strategies are suggested to avoid a substantial decrease in fluorescence quantum yield in condensed media. Finally, the reliability of our theoretical approach is validated by showing the remarkable agreement obtained between the experimental data and the calculated optical properties of clusters formed by sexithienyl molecules.
Characterization of Polyparaphenylene Subjected to Different Heat Treatment Temperatures
Authors: Brown S. D. M. , Matthews M. J. , Marucci A. , Pimenta M. A. , Dresselhaus M. S. , Endo M. , Hiraoka T. 
Published: April 2011

AbstractWe investigated the structural and electronic properties of samples of polyparaphenylene (PPP), derived from two synthesis methods (the Kovacic and Yamamoto methods). These samples have been subjected to different heat-treatment temperatures (650 °C ≤ THT ≤ 2000°C) and their properties are compared to the polymer prior to heat-treatment (THT=0°C). The photoluminescence (PL) spectra of heat-treated PPP based on the two synthesis methods reflects the differences in electronic structure of the starting polymers. The PL emission from the heat-treated Yamamoto polymer is quenched at much lower THT than from the Kovacic material. However, Raman spectra taken of the material resulting from heat-treatment of the polymer (using both preparation methods) indicate the presence of phonon modes for PPP in samples at THT up to 650°C.
Optical Properties of Distyrylbenzene Chromophores and their Segmented Copolymers
Authors: Benfaremo Nicholas , Sandman Daniel J. , Tripathy Sukant , Kumar Jayant , Yang Ke , Rubner Michael F. , Lyons Cormac 
Published: April 2011

AbstractA new segmented polymer (3) consisting of a distyrylbenzene chromophore separated by polyethylene glycol segments has been prepared by two independent methods: a novel, polymer analogous Mitsunobu reaction and conventional double displacement reaction. The polymer is soluble in a variety of organic solvents, forms excellent, optically clear films and exhibits strong fluorescence. The properties of the chromophore and the polymer, as well as the scope and limitations of the novel Mitsonobu polymerization are presented. Attempts to use polymer (3) in electroluminescent devices are also discussed.
Concentration Dependence of Photoluminescence and Electroluminescence in 2,5 Bis[2'-(4”-Hydroxyhexanol Benzyl)-l'-Ethyl]3,4-Dibutyl Thiophenes
Authors: Blumstengel S. , Sokolik I. , Dorsinville R. , Voloschenko D. , He M. , Chien L.-C. , Lavrentovich O. 
Published: April 2011

AbstractA new thiophene-based compound 2,5 bis[2'-(4”-hydroxyhexanol benzyl)-l'-ethyl]3,4-dibutyl thiophene (HBDT) as well as a copolymer (HBDT-PU) consisting of alternating HBDT and urethane spacer units were synthesized. Absorption and luminescence properties of both compounds were studied in solution and in different polymer matrices. Absorption and luminescence spectra of HBDT and HBDT-PU coincide indicating that emission in HBDT-PU occurs from the thiopene containing unit. Photoluminescence (PL) is emitted in the blue-green region of the visible spectrum with a maximum at 460 nm. The PL efficiency of both compounds is strongly enhanced when dispersed in a PVK or PMMA matrix indicating that concentration quenching occurs in the pure material. Light emitting devices were fabricated utilizing a PVK/PBD blend doped with HBDT and HBDT-PU at different concentrations as emitter material. The electroluminescence (EL) spectra coincided with the PL spectra of HBDT indicating that EL emission originates from the dopant molecules. The dependence of the EL efficiency on the doping concentration was measured and found to be close to the concentration dependence of the PL quantum yield.
Control of Emissive Layer Interfaces with Inorganic Thin Layer Between 8-Hydroxyquinoline Aluminum and Diamine Layers in Organic El Diode
Authors: Ohmori Yutaka , Kurosaka Yoshitaka , Tada Norio , Fujii Akihiko , Yoshino Katsumi 
Published: April 2011

AbstractControl of organic interfaces by insertion of a thin inorganic film (SiO) has been investigated for an organic electroluminescent (EL) diode which consists of 8-hydroxyquinoline aluminum (Alq3) and diamine derivative (TPD). In order to evaluate optical quality of the emissive layer at the interface, thin film of emissive marker layer was inserted into the emissive layer at the interface between the emissive layer and the carrier transport layer. The EL emission spectrum and the optical characteristics have been discussed for the EL diode with and without inorganic film.
Latex-Like Water-Borne Polyaniline for Coating Applications
Authors: Liu Huaibing , Clark Robert , Yang Sze C. 
Published: April 2011

AbstractWe report the synthesis of a polymeric complex of polyaniline that is dispersed in water as a stable suspension. The polymer, PAN:PVME-MLA, is a molecular complex of polyaniline and poly(vinylmethylether-co-maleic acid). The synthetic process leads to a stable latex-like suspension in water. The water-borne conducting polymer, once dried as a thin film on a substrate, is not dissolvable by water or other solvents. An example of piece-dyeing process is presented to show its potential for electrostatic dissipation of textile products. Another example illustrates that the material may be used as electroactive thin-films for electrochromic windows and for rechargeable battery applications.
Structural Properties Of Hexaphenyl Powder Under High Pressure
Authors: Guha S. , Graupner W. , Resel R. , Chandrasekhar M. , Chandrasekhar H. R. , Leising G. 
Published: April 2011

AbstractWe present X-ray and Raman studies of the conjugated oligomer, hexaphenyl, which forms polycrystalline layers. The Raman studies have been carried out under hydrostatic pressures up to 70 kbar. The relative intensity of the two modes at 1220 cm−1 and 1280 cm−1 shows the influence of planarization under hydrostatic pressure. These results are interpreted within the framework of theoretical calculations and compared with X-ray studies.
Electrical and Microwave Properties of Mn Implanted (Ba,Sr)TiO3 Thin Films
Authors: Baniecki J. D. , Laibowitz R. B. , Shaw T. M. , Duncombe P. R. , Neumayer D. A. , Cope M. , Kotecki D.E , Shen H. , Ma Q. Y. 
Published: April 2011

ABSTRACTWe have used ion implantation to dope polycrystalline BaxSr(1−x)TiO3 (BST) thin films with Mn. Dopant concentrations were varied in the range of 0.1 at % to 2 at % Mn. X-ray diffraction and TEM studies show that the implantation process significantly damages the film leaving only short range order, but subsequent rapid thermal annealing heals the damage. The effect of the different Mn dopant concentrations on the electrical properties of the complex capacitance, relaxation currents, leakage, C-V, and resistance degradation was investigated. Our initial results show that the implanted films have significantly lower leakage (up to a factor of 10 lower) than the as deposited films for small (<0.5 at % Mn) implantation doses. The capacitance decreased with increasing Mn concentration while the relaxation currents and loss tangents increased.
Study of KTN Thin Films of Variable Composition grown by Pulsed Laser Deposition
Authors: Fernandez F. E. , Pumarol M. , Marrero P. , Rodriguez E. , Mourad H. A. 
Published: April 2011

ABSTRACTPotassium niobate tantalate (KTN) thin films of a range of compositions were grown by pulsed laser deposition onto (100) MgO substrates. Three-segment targets were used including KTaO3, KNbO3, and KNO3. Resulting films were well oriented with the substrates, with the “cubic” (h00) peaks positions shifting with Nb content to that of the (hh0) orthorhombic KNbO3 peak.
Thickness Mode Resonance of PZT Coatings on a Substrate
Authors: Lukacs M. , Olding T. , Sayer M. , Sherrit S. 
Published: April 2011

ABSTRACTThe analytical solution of the wave equation for a piezoelectric layer supported by a substrate is presented. Using the appropriate boundary conditions, the impedance for a piezoelectric layer driven in the thickness axis is derived and expressed in terms of the mechanical, electrical and piezoelectrical properties of the two materials. This solution allows for the extension of the free resonator IEEE impedance techniques and provides a nondestructive method for determining the material parameters of a piezoelectric film with mechanical support. The validity and universality of the model is demonstrated by measurements on composite sol gel PZT coatings within the thickness range of 15-70μm on aluminum substrates of varying thickness, and by simulating the mass loading of a quartz thickness resonator.
Properties of PTO/YBCO Heterostructure on Bare SiC Substrates
Authors: Duan M. , Linnros J. , Petersson C. S. , Rao K. V. 
Published: April 2011

ABSTRACTThe lead titanium oxide PbTiO3 (PTO) and High Tc Superconductor YBa2Cu3O7-x (YBCO) capacitor hetero structures have been fabricated by pulsed laser ablation directly on 3C-SiC substrates. X-ray diffraction analysis indicates that both PTO layer and YBCO layer are polycrystalline with a perovskite phase. The zero-field cooling (ZFC) curve of YBCO shows a transition temperature Tc around 60 K with a ΔTc ≈ 10 K in a dc SQUID measurement. The ferroelectric properties of the capacitors were characterized by a RT66A apparatus.
High-Resolution Optical Microscopy Of BaXSr1−xTio3 Films
Authors: Hubert C. , Levy J. , Carter A. C. , Chang W. , Pond J. M. , Horwitz J. S. , Chrisey D. B. 
Published: April 2011

ABSTRACTThe ferroelectric polarization of thin films of BaxSr1−xTiO3 is imaged using confocal scanning optical microscopy (CSOM). The thin films are grown by pulsed laser deposition (PLD) on SrTiO3 substrates. Ferroelectric domain structure is imaged by applying a small ac electric field across interdigitated electrodes, and measuring induced reflectivity changes in the film, which are directly related to the polarization. Domain re-orientation is observed by acquiring CSOM images as a function of the dc electric field. Local hysteresis loops are obtained by sweeping the dc electric field at fixed positions on the sample. Micrometer-sized regions exhibit both ferroelectric and paraelectric response, indicating that thermal broadening of the phase transition is largely due to inhomogeneities in the thin films.
PECVD of Amorphous Silicon Carbide from Trimethylsilane
Authors: Kelliher J. T. , Massuda M. , DiFonzo P. A. , Neal T. R. 
Published: April 2011

ABSTRACTAmorphous silicon carbide (SiC) was deposited by plasma enhanced chemical vapor deposition (PECVD) in an Applied Materials (AMT5000) tool from sources of trimethylsilane (3MS) and either argon or nitrogen. A deposition rate of ≈ 800 nm/min on a 150 mm silicon wafer was achieved at 350°C. Process conditions investigated were temperature (200–400°C), power (100–600W), pressure (2–8 torr), gas flow rates, and spacing. Various process condition regimes generated a high particle count that was eliminated by controlling parameters of pressure and spacing. Ellipsometry and n&k Analyzer techniques determined the index of refraction. The index of refraction was in agreement between both tools and range from 1.79–2.36 depending on the 3MS flow (25–100 seem) and carrier gas. A Prometrix FT500 with a fixed index of refraction measured 49 points of thickness determined the uniformity. The SiC films stoichiometric composition was measured by X-ray Photoelectron Spectroscopy (XPS). Small quantities of oxygen or nitrogen were found. Additional properties examined were crystallinity, stress, and pinhole density. Dielectric constant was measured by CV techniques.
Solution Processing of YBa2Cu3OT7-x Thin Films
Authors: Singhal A. , Paranthaman M. , Specht E. D. , Hunt R. D. , Beach D. B. , Martin P. M. , Lee D. F. 
Published: April 2011

ABSTRACTThe aim of this work was to develop a non-vacuum chemical deposition technique for YBa2Cu3O7-x (YBCO) coated conductors on rolling-assisted biaxially textured substrates (RABiTS). We have chosen the metal-organic decomposition (MOD) and sol-gel precursor routes to grow textured YBCO films. In the MOD process, yttrium 2-ethylhexonate, barium neodecanoate, copper 2-ethylhexonate and toluene were used as the starting reagents. YBCO films processed by the MOD method on SrTiO3 (100) single crystal substrates were predominately epitaxial and consisted of c and a-axis oriented material. Films have a TC,onset of 89K and the best superconducting transition temperature of 63K. Films pyrolyzed at 525 °C and subsequently annealed at 780 °C in P(O2) of 3.5 × 10−4 atm contained YBCO phase predominately in a-axis orientation. In the sol-gel route, yttrium-isopropoxide, barium metal, copper methoxide and 2-methoxyethanol were used as the starting reagents. Sol-gel YBCO films on SrTiO3 substrates were epitaxial and c-axis oriented.
The Spray Deposition of Transition Metal Nitride thin Films Using Alcohol Based Precursor Solutions
Authors: Weil K. S. , Kumta P. N. 
Published: April 2011

ABSTRACTA new alcohol solution based approach has been developed for preparing transition metal nitride thin films and coatings. In this technique, the metal of interest is dissolved as a chloride in acetonitrile, then chelated with triethanolamine to form a highly viscous solution which settles out of the solvent phase. The acetonitrile is then evaporated off and the remaining thick liquid precursor is easily diluted with water or methanol, yielding a semi-viscous liquid which can be used directly to coat various substrates. When heat treated under the appropriate conditions in ammonia, the precursor coating transforms to yield the corresponding nitride. This approach is currently being considered for preparing nitride-based thin film electrical components and has been successfully used thus far to spray deposit TaN and NbN nitride films onto silicon substrates. Results of the preliminary study on these two nitride films are discussed in this paper.
Colossal Magnetoresisttve Tffin Films of (La1-x,Prx)0.7Ca0.3MnO3 Prepared by Aerosol MOCVD
Authors: Gorbenko O. Yu. , BOSAK A. A. , KAUL A. R. , BABUSHKINA N. A. , BELOVA L. M. 
Published: April 2011

ABSTRACTThin epitaxial films of (La1-x,Prx)0.7Ca0.3MnO3 (x=0,0.25,0.5,0.75,l) were grown on LaA1O3, SrTiO3 and ZrO2(Y2O3) by aerosol MOCVD at 750°C Variation of x greatly influences the electrical properties of material by changing of the tolerance factor t. The tensile strain in the films on perovskite substrates produces the effect on the maximum resistivity temperature Tp comparable with the effect of chemical pressure nearby critical value of t ∼ 0.91. By variation of x the colossal magnetoresistance in very low magnetic fields was achieved in the thin films: an applied field of 0.3 T was enough for 32 times decrease of the resistivity of (La0.35,Pr0.35)Ca0.3MnO3 film on LaA1O3 at 155 K. The charge ordering starting in (La1-x,Prx)0.7Ca0.3MnO3 at 160–210 K leads to the switching from Arrhenius law (lggρ ∼ T1 ) to Mott law (lgρ ∼ T1/4) of resistivity. Large-angle boundaries dominating the structure of the films on ZrO2(Y2O3) increase the resistivity both above and below Tp.
Chemical and Sonochemical Approaches to the Formation of VO2 Films and VO2-Impregnated Materials
Authors: Keppens V. , Mandrus D. , Boatner L. A. 
Published: April 2011

ABSTRACTA new chemical and chemical/ultrasonic approach to the preparation of VO2 films and VO2-impregnated bulk materials has been developed. In this approach, a V2O5 sol prepared by quenching is used to coat SiO2 substrates. The resulting gel-film is heat treated in a reducing atmosphere to form a film identified as VO2 from the results of X-ray diffraction and both optical and resistivity measurements, which reveal the phase transition characteristic of vanadium dioxide. The advantage of this approach to the formation of VO2 is that the V2O5 sol can be used to impregnate porous materials, which are then heat treated to form an optically active composite material. The switching properties of the VO2 films are investigated using optical and resistivity measurements, and the results are compared to those obtained for VO2-films prepared by more-conventional methods.
Chemical Vapor Deposition of Strontium Ruthenate Thin Films from Bis(2, 4-Dimethylpentadienyl) Ruthenium and Bis(Tetramethylheptanedionato) Strontium
Authors: Breitkopf Richard , Meda Lamartine J. , Haas Terry , Kirss Rein U. 
Published: April 2011

ABSTRACTAdherent, polycrystalline films containing mixtures of SrRuO3, Sr2gRuO4 and RuO2 were deposited on silicon and alumina substrates by hot wall chemical vapor deposition from bis(2, 4-dimethylpentadienyl) ruthenium and Sr(thd)2 between 650 and 700°C. The as-deposited mixed phase films, which contained polycrystalline phases of RuO2 and amorphous phases of the mixed oxide exhibited resistivities between 6.5 and 20 mΩcm. Rims were annealed at 1000°C under oxygen/argon ambient. The annealed films exhibited higher resistivities than their as-deposited counterparts and a substrate dependence of phases present was observed. The decrease in conductivity upon annealing for films on both substrates is attributed to the formation of volatile ruthenium oxides. The higher conductivity of post-annealed samples on alumina (compared to samples prepared and annealed on Si) is attributed to Sr uptake by the substrate and thus a suppression of Sr2RuO4 formation.
Macroporous Materials with Uniform Pores by Emulsion Templating
Authors: Imhof A. , Pine D. J. 
Published: April 2011

ABSTRACTA method was developed for the production of macroporous oxide materials by using the droplets of a nonaqueous emulsion as the templates around which material is deposited through a sol-gel process. Moreover, uniform pores arranged in regular arrays can be obtained by starting with an emulsion of uniform droplets. These droplets first self-assemble into a colloidal crystal after which gelation of the suspending sol-gel mixture captures the ordered structure. After drying and calcination pellets are obtained which contain ordered arrays of spherical pores left behind by the emulsion droplets. The method can be used to make uniform pores in the range from 0.05–5 micrometers in many different materials. We demonstrate the process for titania, silica, and zirconia.
Hybrid Catalysts: Internal or External Configuration for Better Catalytic Performance?
Authors: Le Van Mao R. , Saberi M. A. , Lavigne J. A. , Xiao S. , Denes G. 
Published: April 2011

ABSTRACTHybrid catalysts with the external configuration for the cocatalyst showed enhanced product diffusion rates in the n-octane hydrocracking, only if the reaction was carried out at relatively high temperatures. In the n-heptane isomerization, direct incorporation of the Al species into the HY zeolite micropores produced sorption sites which positively affected the selectivity to liquid isomers. Such as internal hybrid configuration resulted in a more important increase in the liquid isomer selectivity than that given by the external hybrid configuration, both systems being designed for better product outward-diffusion.
Investigation of the Optical Properties of Diamond-Like Carbon Films
Authors: Kim B. K. , Grotjohn T. A. 
Published: April 2011

ABSTRACTHydrogenated-amorphous carbon films are deposited in a microwave ECR plasma reactor with an rf biased substrate holder using methane-argon and acetylene-argon gas mixtures. The film's optical properties are characterized versus deposition conditions including pressure (1–5 mTorr), rf induced bias (-100 to 20 volts), and argon/hydrocarbon flow ratio. The acetylene-argon discharges show that ion species formed from acetylene are more important than the argon ions, conversely, the methane-argon discharges showed that argon ions are a major ionic species in the deposition. The influence of the thickness of insulating substrates is studied and the feasibility of depositing multilayer a-C:H films with different film properties in each layer is demonstrated.
Cesium-Enhanced R. F. Magnetron Deposition of Carbon Nitride and Diamond-Like Carbon Films
Authors: Murzin I. H. , Hussain M. A. , Tompa G. S. 
Published: April 2011

ABSTRACTWe report the design, manufacturing, and testing of a new cesium enhanced negative carbon ion source that can be useful to synthesize hard and/or electron emitting carbon nitride and diamond-like carbon (DLC) thin films. The design of the source includes a conventional magnetron-sputtering gun, low voltage ion extraction lenses, and a cesium oven to provide cesium vapor for formation of a fractional mono layer of Cs on the carbon target. Cs reduces the surface work function of the carbon target and enhances the emission of negative carbon ions. Argon and argon-nitrogen gas mixtures were used to ignite and sustain the plasma in the chamber. We compare the properties of carbon nitride and DLC films deposited with and without cesium. Nitrogen composition in the Ar-N2 gas mixture was observed to be an important process parameter affecting mechanical properties of the film. The effect of the Cs oven temperature on deposition rate and current absorbed at the substrate was also investigated for RF powers from 0 to 150 W.
Effects of substrate bias on the properties of a-C:H films by DC saddle-field plasma enhanced CVD
Authors: Yoo Young-Zo , Kim HyoGun , Jang HongKyu , Jeong YoungGeun , Kima Geunsik 
Published: April 2011

ABSTRACTHydrogenated amorphous carbon (a-C:H) films were deposited on p-type Si(100) at room temperature by DC saddle-field plasma enhanced CVD using pure methane gas and diluted methane gas by inert gas. The effect of substrate bias (Vs) from 0 V to 400 V on deposition rate, hydrogen content, chemical bonding of the films have been investigated. FT-IR spectrum shows that a-C:H films consist of sp2 and sp3 bondings and the relative intensity ratio of sp2 and sp3,I(sp2)/I(sp3), decreases from 0.28 to 0.19 as the substrate bias changes from 0 V to 400 V. Deposition rates of the films rapidly decrease with increasing Vs up to 200 V, and then slightly decrease over Vs = 200 V. The hydrogen content of the films increase as Vs goes higher and the number of C-H bonds of a-C:H shows the same trend. Only in the range of Vs=0 V and Vs=100 V the Raman band of graphite and disorder is observed. The emission of white photoluminescence (PL) light from the films is observed with the naked eye even at room temperature. The intensity of PL has a maximum at Vs=200 V, then decreases as the Vs changes from 200 V to 400 V. The PL peak shifts to higher energy from 2.15 eV at 100V to 2.45 eV at Vs=400 V. The PL at Vs = 400 V was two times stronger without a peak shift by using an inert gas dilution into methane source compared with that of a film deposited using pure methane.