bluuebunny/crossref_metadata_2025_split huggingface dataset:
pH Effect on the Optical Properties of Peroxo-Titanium Complex
Authors: Cai Ruxiong , Itoh Kiminori , Sun Changqing 
Published: April 2011

ABSTRACTInteresting optical properties of peroxo-titanium hydrogen peroxide complex against pH changes were studied for the first time using an analytical UV-VIS spectrophotometer. A freshly prepared peroxo titanium complex with pH value of 2.21 exhibited an orange color. This color changed to light orange, cloudy yellow, and then translucent pale-yellow as its pH value increased to 3.9, 5.8 and 6.7 or above. UV-VIS spectra show that the fresh complex had an absorption band rising at wavelength around 400 nm to higher energy, but had no maximum peak. A new absorption peak appears at 245nm for the cloudy yellow samples. This is similar to that of colloidal TiO2, which suggests that TiO2 particles might form upon increasing pH value to or above 5.80. The formation of TiO2 particles was accelerated in the pH value range from 6 to 9, but not in the acidic environment. In H2SO4 acidified environment, the color turned red-orange instead, and a strong absorption at 397nm was observed only at pH =0.99. Based on the experimental observations, a model for the color-forming species and possible applications by using the techniques generated from the present study were proposed.
Alkanethiol Mediated Release of Surface Bound Nanoparticles Fabricated by Nanosphere Lithography
Authors: Zhao Jing , Haes Amanda J , Zhang Xiaoyu , Zou Shengli , Hicks Erin M , Schatz George C , Van Duyne Richard P 
Published: April 2011

ABSTRACTThis work presents an innovative approach to produce monodisperse solution-phase triangular silver nanoparticles with well-controlled geometry. Ag nanotriangles are fabricated by nanosphere lithography (NSL), functionalized with alkanethiol molecules and then released from the substrate into solution. The resulting single isolated nanoparticles are subsequently asymmetrically functionalized with alkanedithiol molecules to form dimer pairs. The optical properties of the Ag nanoparticles have been measured using UV-Vis spectroscopy while their structural properties have been characterized using atomic force microscopy (AFM) and transmission electron microscopy (TEM). Theoretical calculations based on Mie theory and the Discrete Dipole Approximation (DDA) method have been done to interpret the optical properties of the released Ag nanoparticles.
Dominant Factor of Squareness in P-E Hsyteresis Loops of MOCVD-PZT Films
Authors: Funakubo Hiroshi , Sumi Akihiro , Morioka Hitoshi , Okamoto Shoji , Yokoyama Shintaro 
Published: April 2011

AbstractThe effects of P-E properties of epitaxially grown rhombohedral Pb(Zr,Ti)O3 film on the film thickness and temperature were systematically investigated. (100)-oriented rhombohedral Pb(Zr0.65Ti0.35)O3 films with 50 - 3200 nm in thickness were grown on (100)cSrRuO3//(100)SrTiO3 substrates by metalorganic chemical vapor deposition (MOCVD). The ratio of the remanent polarization (Pr) to saturation polarization (Psat), the Pr/Psat ratio, at room temperature decreased with decreasing the film thickness. Moreover, the Pr/Psat ratio at 10 K of 180-nm-thick films was smaller than that of 3200-nm-thick film and dropped at lower temperature with increasing the film thickness. These results suggest that the small Pr/Psat ratio of thin film at room temperature is originated to both of small Pr/Psat ratio even at 10K and their drop starting at lower temperature when the temperature increased.
Evaluation of Pb Precursors for Liquid Injection Atomic Layer Deposition of Pb(ZrxTi1-x)O3 Thin Films
Authors: Watanabe Takayuki , Hoffmann-Eifert Susanne , Hwang Cheol Seong , Waser Rainer 
Published: April 2011

AbstractPb(DPM)2 and Pb(TMOD)2 dissolved in ethylcyclohexane were evaluated as precursors for future atomic layer deposition (ALD) of Pb(Zr,Ti)O3 films. PbO films were deposited by a liquid injection atomic layer deposition on Pt-covered Si substrates at different deposition temperature and precursor volume per cycle. Pb(DPM)2 and Pb(TMOD)2 started thermal decomposition at deposition temperature of around 270°C and 320°C, respectively. Against increasing Pb(DPM)2 injection at 240°C, the deposition rate of PbO films saturated at around 1 Å/cycle, but kept increasing at 300°C, which is above the thermal decomposition temperature. The deposition rate of PbO films at 240°C dropped to a constant value with enough purge time after precursor injection and reactant supply. A saturated deposition rate of PbO films was also observed for Pb(TMOD)2 below the thermal decomposition temperature. However, the saturation behavior observed for Pb(TMOD)2 was slower and the saturated growth rate was higher comparing to Pb(DPM)2. In addition, the film thickness of the PbO films had an apparent gradient over the substrates. These results indicate that Pb(DPM)2 shows more reactive and stable chemisorption comparing to Pb(TMOD)2 for the self-limiting growth rate.
New method of ferroelectric thin film characterization using a polarization instability invoked by a voltage cycling
Authors: Yamada Yuki , Shuto Susumu , Kunishima Iwao 
Published: April 2011

AbstractThe polarization change invoked by bipolar pulse cycling stress (voltage cycling) was investigated in detail for a Pt/PZT/Pt ferroelectric capacitor. The remnant polarization increased after voltage cycling, then, it decreased during storage and approached to the initial value. The estimated activation energy of the decay of the gained-polarization during the storage was 0.52eV. This value suggests that the valence change between Ti3+ and Ti4+ is the key of this phenomenon. The model where Ti-related defects pin the polarization was introduced to explain the result. Based on the findings and the model, a combination of voltage cycling and storage is useful to characterize internal defects. We propose this characterization method, named voltage cycling method, as an effective way to analyze internal defects in a ferroelectric capacitor.
Fabrication of Transparent Ferroelectric-Gate Thin Film Transistors with Nonvolatile Memory Operation
Authors: Tokumitsu Eisuke , Senoo Masaru , Shin Etsu 
Published: April 2011

AbstractWe demonstrate transparent thin film transistors (TFTs) with nonvolatile memory operation using Bi4-xLaxTi3O12 (BLT) as a gate insulator and indium tin oxide (ITO) as a channel. ITO is also used for the gate, source and drain electrodes. Drain current-drain voltage (ID-VD) characteristics of transparent ITO/BLT ferroelectric-gate TFTs exhibit excellent n-channel transistor operations. On current of 0.35 mA was obtained when the applied gate voltage is 6V. On the other hand, the off current of the device is as low as 10-10A, which indicates that the ITO channel is sufficiently depleted by the ferroelectric polarization. In addition, drain current-gate voltage (ID-VG) characteristics demonstrate clear counterclockwise hysteresis loop due to the ferroelectric gate insulator. Optical transmittance of the fabricated device is greater than 60% including the quartz substrate.
Local ferroelectric switching properties in BiFeO3microstructures and their piezomagnetic response
Authors: Harnagea Catalin , Cojocaru Cristian Victor , Pignolet Alain 
Published: April 2011

AbstractWe report here the successful fabrication of BiFeO3(BFO) isolated micron-sized structures by pulsed laser deposition. The islands have a relatively constant aspect ratio (height/lateral size) of 0.1-0.3. We present their local ferroelectric characterization, using piezoresponse force microscopy (PFM), showing that the micron-sized BFO islands exhibit a strong piezoresponse and have ferroelectric domains with lateral sizes down to the 100 nm range. We also present here the first results ofMagnetostriction Force Microscopyexperiments performed on these structures. On ferromagnetic samples this method reveals a piezomagnetic or magnetostriction contrast, associated with magnetic domains. In our case, we show that the contrast can be associated to the magnetoelectric effect.
Characterization of Semi-insulating SiC
Authors: Son Nguyen Tien , Carlsson Patrick , Magnusson Björn , Janzén Erik 
Published: April 2011

AbstractElectron paramagnetic resonance was used to study defects in high-purity semi-insulating (HPSI) substrates grown by high-temperature chemical vapor deposition and physical vapor transport. Deep level defects associated to different thermal activation energies of the resistivity ranging from ~0.6 eV to ~1.6 eV in HPSI substrates are identified and their roles in carrier compensation processes are discussed. Based on the results obtained in HPSI materials, we discuss the carrier compensation processes in vanadium-doped SI SiC substrates and different activation energies in the material.
Time-Dependent Bias Stress-Induced Instability of SiC MOS Devices
Authors: Lelis Aivars , Habersat Daniel , Olaniran Fatimat , Simons Brian , McGarrity James , McLean F. Barry , Goldsman Neil 
Published: April 2011

AbstractWe have observed a gate-bias stress induced instability in both the threshold voltage of SiC MOSFETs and the flatband voltage of SiC MOS capacitors. The magnitude of this bias stress-induced instability generally increases linearly with log time, with no saturation of the effect observed, even out to 100,000 seconds. The magnitude also increases with increasing gate field. A positive gate-bias stress causes a positive shift and a negative gate-bias stress causes a negative shift, consistent with electron tunneling into or out of oxide traps near the SiC / SiO2 interface as opposed to mobile ions drifting across the gate oxide. The effect is repeatable.
Kinetics of the Nucleation and Growth of Helium Bubbles in bcc Iron
Authors: Deo Chaitanya Suresh , Srivilliputhur Srinivasan G. , Baskes Michael , Maloy Stuart , James Michael , Okuniewski Maria , Stubbins James 
Published: April 2011

AbstractMicrostructural defects are introduced in materials upon irradiation with energetic particles. These defects can cause degradation of mechanical properties and contribute to material failure. Transmuted helium in irradiated stainless steels exerts deleterious effects on material properties. We have performed kinetic Monte Carlo (kMC) simulations of point defect diffusion and clustering in bcc alpha iron. The model includes helium and vacancy diffusion and spontaneous clustering and dissociation of the point defects from the clusters. We employ the kMC simulations to investigate the time evolution of the point defect configuration leading to defect clustering and bubble formation. The concentration of embryonic point defect clusters is determined as a function of the simulation time.
Effect of Pressure on Electronic Structure of Pb1−xSnxTe Alloys Doped with Gallium
Authors: Skipetrov Evgeny Pavlovich , Golubev Alexander , Dmitriev Nikolay , Slyn'ko Vasily 
Published: April 2011

ABSTRACTThe galvanomagnetic effects in the n-Pb1−xSnxTe:Ga (x=0.09-0.21) alloys at the temperatures 4.2≤T≤300 K and under hydrostatic compression up to 16 kbar have been investigated. It is shown that in all samples and in the whole investigated pressure range temperature dependencies of resistivity and Hall coefficient have a “metallic” character, indicating stabilization of Fermi level by the impurity resonant level. Using the experimental data in the frame of two-band dispersion law the dependencies of the free electron concentration and the Fermi level position upon temperature, matrix composition and pressure were calculated. The temperature, composition and pressure coefficients of gallium resonant level movement were obtained and the electronic structure under varying the alloy composition and under pressure were built.
Developing Biosensors for Monitoring Orthopedic Tissue Growth
Authors: Sirivisoot Sirinrath , Yao Chang , Xiao Xingcheng , Sheldon Brian W. , Webster Thomas J. 
Published: April 2011

ABSTRACTThe objective of this in vitro present study was to create a biosensor which can monitor in situ orthopedic tissue growth juxtaposed to a newly implanted orthopedic material. This biosensor has unique properties including the ability to sense, detect, and control bone regrowth. Such a biosensor is useful not only in regenerating tissue necessary for orthopedic implant success, but also to aid in informing an orthopedic surgeon whether sufficient new bone growth occurred. If the sensor determines that insufficient new bone growth occurred, the sensor can also act in an intelligent manner to release bone growth factors to increase bone formation. The primary biomaterial in this biosensor is anodized Ti, developed by chemical etching and passivation treatments. Carbon nanotubes (CNTs), because of their electrical and mechanical properties, are essential to consider when designing such biosensors since they will be used to apply and measure conductivity changes as new bone grows next to the implant. For this, parallel multiwall CNTs were grown from the pores of the anodized Ti by a chemical vapor deposition process. Lastly, these sensors will be composed of a conductive, biodegradable, polymer layer that degrades when bone grows and, consequently, undergoes a change in conductivity that can be measured by the CNTs grown out of the anodized Ti. This conductive, biodegradable polymer consists of polypyrrole (which is conductive) and poly-lactic-co-glycolic acid (which is biodegradable). Preliminaryin vitroresults suggest that osteoblast functions (specifically alkaline phosphatase activity and calcium deposition) on CNTs grown on anodized Ti are significantly enhanced when compared to anodized Ti and currently-used Ti; thus, it is anticipated that bone growth could be enhanced on these novel biomaterial sensors.
Theoretical Study of Si-Rich Transition-Metal Silicides with Double-Graphene-Like Structures
Authors: Miyazaki Takehide , Kanayama Toshihiko 
Published: April 2011

ABSTRACTWe propose a novel form of graphene-like Si nanostructure based on ab initio total-energy calculation and geometry optimization, (MSi12)n, with M being transition metal atom. It has a three-layer structure, where the two layers of Si atoms in graphene-like positions sandwich another layer of transition metal atoms. The electronic structure may become semiconducting or metallic, depending on the choice of M and arrangement of Si atoms. This hypothetical material can be regarded as a Si-rich phase of transition metal silicide. A potential impact of our finding in forthcoming ultra-scaled Si technology is also discussed.
Nanoscale Transistors: Physics and Materials
Authors: Lundstrom Mark S. , Cantley Kurtis D. , Pal Himadri S. 
Published: April 2011

ABSTRACTWe analyze a modern-day 65nm MOSFET technology to determine its electrical characteristics and intrinsic ballistic efficiency. Using that information, we then predict the performance of similar devices comprised of different materials, such as high-k gate dielectrics and III-V channel materials. The effects of series resistance are considered. Comparisons are made between the performance of these hypothetical devices and future generations of devices from the ITRS roadmap, including double-gate MOSFETs. We conclude that a Si channel device with a high-k gate dielectric and metal gate will outperform III-V channel materials for conventional CMOS applications, but will still not suffice in achieving long-term ITRS goals.
Nucleation Process During Excimer Laser Annealing of Amorphous Silicon Thin Films on Glass: A Molecular-dynamics Study
Authors: Munetoh Shinji , Mitani Takanori , Kuranaga Takahide , Motooka Teruaki 
Published: April 2011

ABSTRACTWe have performed molecular-dynamics simulations of heating, melting and recrystallization processes in amorphous silicon (a-Si) thin films deposited on glass during excimer laser annealing. By partially heating the a-Si surface region with 2 nm depth and removing thermal energy from the bottom of the glass substrate, a steady-state temperature profile was obtained in the a-Si layer with the thickness of 15 nm and only the surface region was melted. It was found that nucleation predominantly occurred in the a-Si region as judged by the coordination numbers and diffusion constants of atoms in the region. The results suggest that nucleation occurs in unmelted residual a-Si region during the laser irradiation and then crystal growth proceeds toward liquid Si region under the near-complete melting condition.
Band-Gap Modulation and Kohn Anomalies in Two-Dimensional Graphite and Single-Wall Carbon Nanotubes
Authors: Samsonidze Georgii , Barros Eduardo B. , Son Hyungbin , Saito Riichiro , Dresselhaus Gene , Dresselhaus Mildred S. 
Published: April 2011

ABSTRACTThe electron-phonon coupling in two-dimensional graphite (graphene sheet) and metallic single-wall carbon nanotubes (SWNTs) is analyzed. In the graphene sheet the G-band phonon mode induces oscillations of the Fermi points, while the G′-band phonon mode opens a dynamical (oscillating with the phonon frequency) band gap, and accordingly, both phonon modes exhibit Kohn anomalies. Similarly, truly metallic armchair SWNTs undergo Peierls transitions driven by the G−- and G′-band phonon modes both of which open a dynamical band gap. In addition, the dynamical band gap induces a non-linear dependence of the phonon frequencies on the doping level and gives rise to strong anharmonic effects in the graphene sheet and metallic SWNTs.
FET Properties of Surface Silylated Single Wall Carbon Nanotubes
Authors: Kumashiro Ryotaro , Hiroshiba Nobuya , Ohashi Hirotaka , Akasaka Takeshi , Maeda Yutaka , Suzuki Shinzo , Achiba Yohji , Hatakeyama Rikizo , Tanigaki Katsumi 
Published: April 2011

ABSTRACTSingle wall carbon nanotubes (SWNTs) having semiconducting properties are promising as electronic materials for nano-scale devices in the future, and the electrical properties of SWNTs are of significantly fundamental and practical interests. It is well known that the field effect transistors (FETs) fabricated using semiconducting SWNTs show high performance in terms of the mobility. However, carriers in pristine SWNTs are mostly holes and, therefore, SWNTs -FETs usually show p-type properties. As for SWNTs, chemical carrier doping has been reported so far for controlling carrier concentration like graphite intercalations. Two major techniques in SWNTs are generally possible; one is endohedral doping and the other is the exohedral chemical modifications. It has been exemplified that doping with alkali metals can introduce electron carriers into SWNTs. Furthermore, the electrical transport properties of SWNTs were reported to be controlled by the endohedral insertion of organic molecules inside the SWNTs. A similar carrier doping could exohedrally be possible when the SWNTs surface is chemically modified. With such chemical modifications, the charge transfer from the substituent groups to SWNTs will be expected and this could modify the electronic states of SWNTs. We reported the FET properties of individual SWNTs exohedrally modified by Si-containing organic moieties, and demonstrated that p-type nanotubes can be converted to n-type ones. However, because of ununiformity of the surface-chemical modifications of SWNTs, the true effects of the exohedral modifications on FET properties were extremely difficult to be evaluated. In this meeting, we will present comparison of the FET properties of the exohedrally silylated SWNTs between separated individual and spread-sheet samples. For evaluating the FET properties, the chemically modified SWNTs have been dispersed on a FET substrate, and the measurements have been carried out at ambient temperature using a conventional method for a separated SWNTs and a spread-sheet SWNTs film. As a reference, the experiments were also made in the same manner on chemically non-modified CNTs. From the experimental results, it will be demonstrated that an n-type property can be enhanced by the exohedral modifications both in the case of the spread-sheet samples and in the case of the individual ones. We will discuss the effects of surface silylation on the electronic states of these SWNTs.
Dependence of the Raman Spectrum of Silicon Nanowires on the Wire Environment
Authors: Scheel Harald M. , Reich S. , Thomsen C. 
Published: April 2011

ABSTRACTThe large surface to volume ratio in nanometer sized wire structures cause a strong dependence of the optical Raman mode on the thermal conductivity of a surrounding medium. On the basis of optical measurements on silicon nanowires as a function of excitation laser power we explain the very large red-shifted Raman spectra observed already for moderate laser powers. This thermal effect is enhanced by a silicon oxide sheath, rendering a reduced thermal contact of the wires to the substrate. The intrinsic redshift due to spatial confinement in silicon nanowires is found to be smaller than 2 cm−1.
Elastic Properties of Normal and Binormal Helical Nanowires
Authors: da Fonseca Alexandre Fontes , Malta C P , Galvão Douglas S 
Published: April 2011

ABSTRACTA helical nanowire can be defined as being a nanoscopic rod whose axis follows a helical curve in space. In the case of a nanowire with asymmetric cross section, the helical nanostructure can be classified as normal or binormal helix, according to the orientation of the cross section with respect to the helical axis of the structure. In this work, we present a simple model to study the elastic properties of a helical nanowire with asymmetric cross section. We use the framework of the Kirchhoff rod model to obtain an expression relating the Hooke's constant, h, of normal and binormal nanohelices to their geometric features. We also obtain the Young's modulus values. These relations can be used by experimentalists to evaluate the elastic properties of helical nanostructures. We showed that the Hooke's constant of a normal nanohelix is higher than that of a binormal one. We illustrate our results using experimentally obtained nanohelices reported in the literature.
Fabrication and Characterization of Nickel Nanowire Polymer Composites
Authors: Denver Heather , Hong Jeongmin , Borca-Tasciuc Diana-Andra 
Published: April 2011

ABSTRACTMagnetic polymers are multi-functional composites emerging as a new category of smart materials. This work focuses on fabrication and characterization of magnetic polymer nanocomposites based on polydimethylsiloxane (PDMS) elastomer matrix. The magnetic fillers are commercially available Ni nanoparticles and respectively in-house fabricated Ni nanowires. Synthesis of Ni nanowires is achieved by electroless deposition inside nanoporous anodic alumina templates. After template removal, the nanowires are coated with 1-Octodecanethiol surfactant and mixed with PDMS using a FlackTek SpeedMixer™. In parallel, nanoparticles are mixed with PDMS, without undergoing surfactant coating. Both composites are evaluated by scanning electron microscope (SEM) to determine dispersion uniformity. Mechanical properties are resolved by tensile tests performed by an instron. Preliminary results suggest that surfactant addition enhances dispersion, while mechanical properties of the composites for up to 5 vol. % of added nickel remain close to that of the polymer matrix without filler.
The Molecular Structures and Properties of Novel Eu(III) Complexes with Asymmetric Bis-phosphine Oxides
Authors: Iwanaga Hiroki , Aiga Fumihiko , Amano Akio 
Published: April 2011

ABSTRACTSeveral novel Eu(III) complexes with asymmetric bis-phosphine oxide- ligands were synthesized. The relation between molecular structures of bis-phosphine- oxide ligands and properties of Eu(III) complexes was investigated and some interesting results were obtained. Solubility of Eu(III) complexes in fluorinated medium and silicone oil were strongly dependent on the length of alkyl chain (n) binding two phosphine oxide- parts. Also, the thermal properties of Eu(III) complexes were correlated to the solubility. Eu(III) complex 6(n=3), which has phenyl and n-octyl groups as the substituents of a bis-phosphine oxide- ligand, was found to be highly soluble and have large fluorescence intensity.