bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spectroscopic Study of Titanium Oxide Thin Films at Low Temperatures by X-ray Diffraction, Raman Scattering, Fourier Transform Infrared Spectroscopy and Photoluminescence
Authors: Zhao Zhiwei , Tay Beng Kang 
Published: April 2011

ABSTRACTTitanium oxide thin films were prepared by filtered cathodic vacuum arc (FCVA) at low temperatures ranged from room temperature to 330°C. Spectroscopic study of the deposited films were carried out by X-ray diffraction, Raman Scattering, Fourier transform infrared spectroscopy (FTIR) and photoluminescence (PL), respectively. The films remained amorphous up to the substrate temperature of 230°C. Nanocrystalline titanium oxide thin films occurred at 330°C with the strongest peak intensity from anatase (101) plane. The average grain size was around 20 nm and no rutile phase could be found. Various allowed vibrational frequencies (e.g. 152, 199, 399, 640 cm−1) in Raman spectra and Ti-O-Ti transverse mode at 436 cm−1 in the FTIR spectrum evidently verified the presence of anatase phase in the films at 330°C. Moreover, at room temperature only crystalline film exhibited a PL peak with the center at 379 nm in PL spectrum and the origin was discussed.
Effect of Polyvinylpyrrolidone Molecular Weight on the Critical Thickness, Crystallization, Densification and Properties of PLZT Films
Authors: Du Zehui , Ma J. 
Published: April 2011

ABSTRACTPLZT 9.5/65/35 ceramic films were prepared from the sol-gel solutions containing the stress-relaxing agent of polyvinylpyrrolidone(PVP) with the molecular weight of 40000, 360000 and 630000 (abbreviated as PVP40, PVP360 and PVP630) respectively. It is found that PVP40 can increase the critical thickness of the PLZT films to 0.22μm(compared with the critical thickness of 0.077μm in case of without PVP) and PVP360 and PVP630 can increase the critical thickness up to 0.49μm and 0.93μm individually. With the molecular weight of PVP increasing, the perovskite formation in the PLZT films was improved but the morphology of the films tended to be nano-porous. The films modified by PVP360 can be densified by optimizing the heat treatment conditions. When pyrolyzed at 600°C and then annealed at 700°C, the one-coating films with the thickness of 0.5μm were dense and exhibited a very slim hysteresis loop with the remnant polarization of 5.96×10−4μC/cm2 and coercive field of 21.51kV/cm, and a transmittance of around 90% and above in the wavelength of 450nm∼900nm.
Annealing and Persistent Photoconductivity Effects in Amorphous and Crystalline Vanadium Oxide Films
Authors: Kekas Jason , Dhawan Anuj , Gollakota Praveen , Muth John 
Published: April 2011

ABSTRACTVanadium dioxide films have long attracted attention because of the phase transition between the semiconducting state and the metallic state at 68 degrees centigrade. Vanadium oxide films have been prepared by a variety of methods, including the annealing and oxidation of evaporated vanadium under controlled conditions. In this study we explore a different route by producing amorphous and crystalline VOx films by pulsed laser deposition and annealing under a variety of conditions. We found that that in amorphous films grown at lower temperatures and then annealed, persistent photoconductivity effects can be observed, while in epitaxial crystalline films grown at high temperature, persistent effects were not observed. Furthermore, it was found that for some crystalline films persistent optical effects were observed and that optical hysteresis was dependent on the amount of time after the film anneal.
Magnetic Resonance Imaging (MRI) of Water Diffusion in 2-Hydroxyethyl Methacrylate (HEMA) Gels
Authors: Raguin Guy , Falkenberg Cibele V. , Prakash Shaurya , FitzHenry Heather R. , Mensing Glennys , Ciobanu Luisa , Georgiadis John G. , Shannon Mark A. 
Published: April 2011

ABSTRACTA fundamental study focusing on correlating the local water self-diffusion coefficient to the local free water content in 2-hydroxyethyl methacrylate (HEMA) gels was conducted. HEMA gels were synthesized with different nominal water content (50% to 90%). MRI measurements of local diffusion coefficient distribution and local water content profiles are conducted on a 600 MHz scanner. The local water content is measured via two spin-echo images with sufficiently long repetition time (TR) to eliminate T1-weighting and two values for the echo time (TE) in order to account for T2-weighting. The local diffusion coefficient is determined using a standard pulsed-field gradient spin-echo sequence. The measured local water content and diffusion coefficient data are compared with several single-parameter diffusion models for interstitial diffusion in the hydrogel (Makie-Meares, Stokes-Einstein, Brownian motion around overlapping spheres).
Infusion of Nanotechnology in Chemistry Courses Through Laboratory Redesign and Vertical Threads
Authors: Nivens Delana A. , Lynch Will E. , Helmly Brian C. , Nguyen Nguyen T. , Dingra Nin , Chow Joyce , Svendsen Amanda , Harris Beverly D , Meeks April , Dyal Cassandra , Hadden Jodi , Tibah Denis M 
Published: April 2011

ABSTRACTChemistry occupies a unique place in the university curriculum and is required by a wide variety of other disciplines because of its general utility. Unfortunately, the laboratory portion of the course does not always reflect the diversity and excitement of new research in and interesting applications of chemistry since the laboratory experience is designed to help the student master fundamental concepts. At Armstrong Atlantic State University (AASU) we are attacking this problem with the implementation of two series of nanotechnology based “vertical threads” throughout our chemistry curriculum. The vertical threads begin in the freshman year and provide continuity throughout the rest of the curriculum. Experiments direct the student's attention towards modern applications of chemical technology while providing chemical fundamentals expected in traditional laboratory exercises. By seeing these recurring threads at ever increasing levels of complexity, students build upon knowledge gained about nanotechnology with each additional laboratory course.The approach used at AASU created two experimental “vertical threads” which are woven into the educational experience from the bottom-up in both the curriculum and the chemical methodology. Experiments performed in the freshman chemistry lab reappear in expanded forms in subsequent years as part of new experiments that mimic the biological, industrial and medical applications of nanotechnology.We have concentrated our efforts in two areas: magnetite nanoparticles thread, and the chalcogenide nanoparticles thread. Magnetite nanoparticles are prepared by freshmen students while more advanced students modify these nanoparticles for real-world applications. Chalcogenide nanoparticles are synthesized by junior and senior level students and their spectroscopic properties are studied. Senior and undergraduate research students are involved in green synthesis of silver and gold nanoparticles as well as the use of ZnS, CdS and ceria nanoparticles for photocatalysis applications. The upper division students learn numerous instrumental techniques (i.e. UV-VIS, Fluorescence, FT-IR) within the context of nanotechnology. All students are presented with pre-laboratory and background materials that address the needs for new materials, new techniques for biomedical analysis and drug delivery as well as the environmental impacts of nanotechnology.
Nanotechnology Education: The Pennsylvania Approach
Authors: Fonash Stephen , Fenwick Douglas , Hallacher Paul , Kuzma Terry , Brunner Amy , Mahoney William , Ehrmann Robert 
Published: April 2011

ABSTRACTA workforce educated at the two-year degree and four-year degree level in nanotechnology, nanofabrication, and nano-scale characterization is required to grow and sustain nanotechnology manufacturing, and R&D. Pennsylvania has addressed this need with the creation of the Nanofabrication Manufacturing Technology (NMT) Partnership, a state-wide collaborative involving Penn State University, Pennsylvania College of Technology, all of the community colleges in PA, the 14 universities of the state-system, PA state government, the National Science Foundation, and PA industry. This partnership is based on sharing the expertise and facilities at Penn State's University Park campus with partner colleges and universities across the state. With this state-wide approach, the NMT Partner educational institutions can offer two-year degrees in nanotechnology and four-year degrees in biology, physics, and chemistry, with a concentration in nanotechnology, across PA. With the Partnership approach, participating institutions are also able to offer three-day Nanotech Camps for secondary school students, three-day nanotechnology workshops for secondary school teachers, and a variety of tools and materials for introducing nanotechnology into the secondary school classroom.
Advanced Inter-/Multi-Disciplinary Graduate-Level Programs for Education, Research, and Training in Nanoscience and Nanotechnology Offered at Osaka University
Authors: Itoh Tadashi , Akai Hisazumi , Ogawa Hisahito , Diño Wilson Agerico , Ichikawa Satoshi , Matsui Hiroaki , Ara Masato , Yoshiki Keisuke 
Published: April 2011

ABSTRACTNanoscience: an area that promises new understanding of nature with the aid of rapid progress of nanotechnology. Nanotechnology: the use of nanoscience to build new technologies that will change the world. Nanoscience and Nanotechnology have captured the attention of the public, government, and corporations. How they will influence our lives depend on how we prepare ourselves, and our successors. Here we present a brief outline of the efforts being taken at Osaka University since 2004, in order to prepare our future scientists, engineers, and leaders in the rapidly flourishing trans-/multi-disciplinary field of Nanoscience and Nanotechnology.
Modeling Misfit Dislocation Arrays for the Growth of Low-Defect Density AlSb on Si
Authors: Jallipalli Anitha , Balakrishnan G. , Huang S.H. , Khoshakhlagh A. , Dawson L.R. , Huffaker D.L. 
Published: April 2011

ABSTRACTWe present analytical models and experimental results to describe low-defect density growth (∼ 6 × 105/cm2) of highly mismatched antimonides on Si and GaAs substrates, with strain relief achieved at the growth interface through periodic, 90° interfacial misfit dislocations (IMF). We use molecular mechanics (MM) based modeling techniques to understand, at the atomic level, the spontaneous formation and energetics of these IMF. We have modeled, grown and characterized two systems extensively, these are - AlSb on Si with ∼ 13% mismatch and GaSb on GaAs with 7.83% lattice mismatch. Growth of these materials by molecular beam epitaxy (MBE) and subsequent High-Resolution Transmission Electron Microscopy (HR-TEM) has indicated that there is no tetragonal distortion in these two systems despite the high lattice mismatch. Instead, the mismatched epi-layers spontaneously form periodic IMF arrays that run along both [110] and [1-10] directions and relieve almost 100% of the strain in a few monolayers of deposition. To model this form of strain relief, we use existing theories of strain relief adapted for very high strain conditions and we also use bond energetics to model the strain-relieving interface. The IMFs in these systems are periodic and so is the deviation in bond lengths and bond angles, which restricts our calculation space to a finite number of elements. We shall also demonstrate extensive growth and characterization results of the materials grown with a particular emphasis on the strain-relieving interface to show excellent agreement of the experimental data with the proposed models. The high quality and low-defect density in AlSb grown on Si, has helped us demonstrate optically pumped IR VCSELs and edge emitters monolithically on Si (001) and this data will also be presented.
Spatially Resolved Characterization of Microstructure, Defects and Tilts in GaN Layers Grown on Si(111) Substrates by Maskless Cantilever Epitaxy
Authors: Barabash Rozaliya , Roder C. , Ice G. E. , Einfeldt S. , Budai J. D. , Liu W. , Barabash O. M. , Figge S. , Hommel D. 
Published: April 2011

ABSTRACTThe spatially resolved distribution of strain, misfit and threading dislocations, and crystallographic orientation in uncoalesced GaN layers grown on Si(111) substrates by maskless cantilever epitaxy was studied by white-beam Laue x-ray microdiffraction, scanning electron microscopy, and orientation imaging microscopy. Tilt boundaries formed at the column/wing interface with the misorientation strongly depending on the growth conditions. A depth-dependent deviatoric strain gradient is found in the GaN. Types and density of misfit dislocations as well as their arrangement within different dislocation arrays was quantified. The results are discussed with respect to the miscut of the Si(111) surface and misfit dislocations formed at the interface.
High Sensitivity Sensor Based on Porous Silicon Waveguide
Authors: Rong Guoguang , Saarinen Jarkko J. , Sipe John E. , Weiss Sharon M. 
Published: April 2011

ABSTRACTPorous silicon (PSi) waveguides are fabricated as a new platform for high sensitivity biosensors. Biomolecules infiltrated into the PSi waveguide increase the effective refractive index of the waveguide and change the angle at which incident light couples into a waveguide mode. Due to the high surface area to volume ratio of PSi and the confinement of optical energy in the region where the biomolecules reside, the waveguide resonance is very sensitive to small concentrations of infiltrated molecular species. A resonance width below 0.1° has been obtained, which is sufficient to detect one monolayer of DNA covering the pore walls. In this work, a prism is used for the waveguide coupling in an arrangement that is similar to traditional surface plasmon resonance (SPR) sensing. Theoretical analysis suggests that an optimized PSi waveguide resonant sensor will show a 60-fold improvement in sensitivity when compared to a conventional SPR sensor due to the enhanced interaction between the electromagnetic field and biological material.
Effect of Silver Nanoparticles in the Hole Injection Layer on the Performance of Organic Light Emitting Diodes
Authors: Kim Jin heon , Lee Joon Ho , Kim Tae-Heon , Seoul Chang 
Published: April 2011

ABSTRACTThe configuration of the OLED device is like this : ITO/PEDOT:PSS(Ag nanoparticle) /NPB/Alq3/AlThe effect of Ag nanoparticles in the hole injection layer on the performance of Organic Light Emitting Diodes(OLED) was investigated.The hole mobility in the hole injection layer seems to be increased by Ag nanoparticles.The increased current in the hole injection layer increased the emission efficiency of the OLED.Initially, we try to incorporate silver nanoparticles(diameter:30nm) directly into the hole injection layer. However the Ag nanoparticles are aggregated into big particles, ( size 1∼2 μm). We can confirm this behavior by the optical microscope. Thus, PEDOT:PSS/Ag nanoparticles solutions were filtered before spin-coating and big particles were eliminated by this process.The several silver nanoparticles concentration were selected (0.05, 0.1, 0.25 wt % of the silver nanoparticles was mixed with PEDOT;PSS solutions). Theses solutions were spin-coated on the ITO layer with 3000 rpm for 60 secs. The spin coated Ag, PEDOT:PSS solutions were heat treated at 100 °C in 30 min. The big Ag agglomerate was not observed in the optical microscope. Then the thermal evaporation of the NPB and Alq3 layer was conducted.The current-voltage relation was measured for the device and compared with the OLED device without Ag particle. The lumninance of the devices are also measured. The Ag nanoparticle increases the deriving current and thus increases the quantum efficiency of the OLED.
Electrochromic Properties of Polycrystalline Nb2O5 Thin Films with Mg2+ Ions
Authors: Agarwal Gargi , Reddy G. B. 
Published: April 2011

ABSTRACTSol-gel derived Nb2O5 thin films crystallize to a stable hexagonal phase on annealing at 600°C in air. These films have been intercalated with Mg2+ ions for the first time and the structural and the optical changes on intercalation have been reported. Films were intercalated and deintercalated with Mg2+ ions in galvanostatic mode. Mg intercalated films show about 35% transmittance variations in the entire spectral range. The FTIR studies show the formation of Mg-O-Nb bonds along with the formation of Nb-OH and Mg-O bonds. Small quantities of water is adsorbed during intercalation resulting in the formation of Mg(OH)2. The coloration is completely reversible on deintercalation. Formation of MgNb2O6 phase is seen on intercalation with 1M concentration of the electrolyte, which is found to be 'x' dependent, where ‘x’ is the ratio of the intercalated ions to the Nb atoms. 0.1 M electrolyte does not show the formation of this phase.
A Novel Sigma-Conjugated Hyperbranched Polysilane Polymethylphenylsilane-co-methylsilane (PMPS-co-MS)
Authors: Yu Jiang , Xu Weijian , Zhang Zhenghua , Ni Yu , Lu Yanbing , Xiong Yuanqin 
Published: April 2011

ABSTRACTA novel σ-conjugated hyperbranched polysilane is presented, and it has good solubility in common organic solvents. The photoluminescence (PL) emission spectrum of it exhibits an emission maximum at 425nm, which indicates that the polymer emits blue light. The resulting polymer also has good thermal stability and high glass transition temperature. Therefore, it demonstrates a promising application in blue light emitting diodes.
Hall Effect in Organic Single-crystal Field-effect Transistors
Authors: Takeya Jun , Yamada Koichi , Tsukagoshi Kazuhito , Aoyagi Yoshinobu , Takenobu Taishi , Iwasa Yoshihiro 
Published: April 2011

ABSTRACTWe report Hall effect of charge carriers accumulated in organic field-effect transistors. Rubrene (C42H28) single crystals are shaped in to the Hall-bar congiguration in the devices so that the Hall signal is appropriately detected in external magnetic fields. It turned out that inverse Hall coefficient, having a positive sign, is close to the amount of electric-field induced charge upon the hole accumulation. The observation of the normal Hall effect means that the electromagnetic character of the surface charge is not of hopping carriers but resembles that of a two-dimensional hole-gas system. The direct access to the density of mobile charge carriers provides a tool to understand nontrivial features of organic field-effect transistors such as gate electric field dependent mobility.
Hopping Transport and Voltage Induced Metal-Insulator Transition in Polythiophene Field Effect Transistors
Authors: Dhoot Anoop Singh , Wang Guangming , Moses Daniel , Heeger Alan J. 
Published: April 2011

ABSTRACTWe have studied the carrier transport in regio-regular polythiophene field effect transistors (FETs) by four-probe measurements of the steady-state channel conductance from room temperature to 4.2 K. At high gate voltage (constant total carrier density, n = 5×1012 cm−2) and at low temperatures, we demonstrate that the gate voltage and source-drain voltage combine to induce the insulator-to-metal transition. In the insulating regime, the carrier transport is well described by phonon assisted hopping in a disordered Fermi Glass (with Coulomb interactions between the hopping charge carrier and the charge left behind). At the highest gate voltages and at sufficiently high source-drain voltages, the data imply a zero-temperature transition from disordered insulator to metal.
A Novel Nanotube-on-Insulator (NOI) Approach toward Single-Walled Carbon Nanotube Devices
Authors: Liu Xiaolei , Han Song , Zhang Daihua , Ryu Koungmin , Zhou Chongwu 
Published: April 2011

ABSTRACTWe present a novel nanotube-on-insulator (NOI) approach to produce high-yield nanotube devices based on aligned single-walled carbon nanotubes. First, we managed to grow aligned nanotube arrays with controlled density on crystalline, insulating sapphire substrates, which bear analogy to industry-adopted silicon-on-insulator substrates. Based on the nanotube arrays, we demonstrated registration-free fabrication of both top-gated and polymer-electrolyte-gated field-effect transistors with minimized parasitic capacitance. In addition, we have successfully developed a way to transfer these aligned nanotube arrays to flexible substrates. Our approach has great potential for high-density, large-scale integrated systems based on carbon nanotubes for both micro- and flexible electronics.
Solution-Processed Hybrid Polymer-Quantum Dot Nanocomposite for Infrared Photodetection and Photorefractivity
Authors: Choudhury Kaushik Roy , Kim Won Jin , Sahoo Yudhisthira , Lee Kwang-Sup , Prasad Paras N. 
Published: April 2011

ABSTRACTSuccessful integration of solution-processible nanocrystal quantum dots, active over a wide spectral range in the infrared, organic molecules and polymers, to fabricate efficient photoconductive and photorefractive devices operational at important optical communication wavelengths is achieved. Sensitization of the polymeric composites by quantum dots led to high photocurrents at 1340 nm, yielding a high photoconductive quantum efficiency. In the photorefractive composites, pronounced two-beam coupling was observed, leading to good optical gains achievable by low-power continuous-wave illumination. The photoresponse was further extended to 1550 nm. A steady state diffraction efficiency was obtained in the dynamic refractive-index gratings with appreciable response times. In order to enhance the photoconductive performance of the devices, the organic semiconductor pentacene was incorporated into the hybrid composite through a soluble presursor. At the operating wavelength of 1340 nm, the photocurrent increased significantly as the amount of pentacene in the composite was increased, resulting in a spectacular improvement of external quantum efficiency.
The Preparation and Characterization of a Novolac Cured Epoxy-Clay Nanocomposites
Authors: Tsai Tsung-Yen , Lu Shau-Tai , Li Chih-Hung , Huang Chin-Jei , Chen Li-Chun , Liu Jia-Xiang 
Published: April 2011

ABSTRACTIntercalated or exfoliated nanocomposites were composed by the novolac cured epoxy and one of three different kinds of layered silicates, such as montmorillonite (PK-802), saponite (Semecton-SA) and nontronite (PK-805). The bi-functional modifiers (PI/BEN or MI/BEN) with different ratio, which contained one of the promoters (2-phenylimidazole, PI and 2-methylimidazole, MI) of epoxy and benzalkonium chloride (BEN), were intercalated into the gallery regions of pure clays at the same time and followed by a crosslinking reaction. The properties of novolac cured epoxy/clay nanocomposites were characterized by wild-angle X-ray diffraction (WAXRD), thermal analysis (TGA/DSC), coefficiency of thermal expansion (TMA), mechanical properties (DMA), and transmission electron microscopy (TEM). According to the measurement, these novolac cured epoxy-clay nanocomposites have shown the significant improvement in the thermal, mechanical and barrier properties.
Effect of Silica-Nanoparticle Dispersion on Holographic Recording in Methacrylate-Based Photopolymer Films
Authors: Takahashi Hiroshi , Naitoh Takahiro , Tomita Yasuo 
Published: April 2011

ABSTRACTTransmission volume holograms recorded in two types of methacrylate-based photopolymer films that include benzyl n-butyl phthalate (BBP) or Poly(methyl methacrylate) (PMMA) are studied. It is shown that both BBP and PMMA molecules can be uniformly dispersed into methacrylate monomers and that a refractive index modulation as high as ∼0.005 is recorded by optimizing their volume concentrations. Moreover, it is also shown that the additional doping of silica nanoparticles substantially suppresses polymerization shrinkage without increasing optical scattering loss.