bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation of heteroepitaxial SrRuO3 thin film on Si substrate and microstructure of BaTiO3-NiFe2O4 epitaxial composite thin film deposited on the SrRuO3 bottom electrode using PLD
Authors: Wakiya Naoki , Sakamoto Naonori , Sawamura Shigeki , Fu Desheng , Shinozaki Kazuo , Suzuki Hisao 
Published: September 2011

ABSTRACTA “0-0 type” multiferroic BaTiO3-NiFe2O4 (BT-NF) composite thin film was prepared on SrRuO3/(La,Sr)MnO3/CeO2/YSZ/Si(001) substrate using pulsed laser deposition (PLD). Epitaxial growth of the film was confirmed using x-ray pole figure measurements. Cross-sectional TEM observations revealed that the crystal structure and morphology of the BT-NF composite thin film depends on the oxygen pressure during deposition. The film deposited at 1.0×10-2 Torr has smaller grains than that deposited at 1.0×10-1 Torr. The magnetic and ferroelectric properties of BT-NF composite thin film were correlated with the microstructure that was controlled by oxygen pressure during deposition. The film deposited at 1.0×10-2 Torr had paramagnetic properties with less polarization than the film deposited at 1.0×10-1 Torr.
Graphene growth on SiC and other substrates using carbon sources
Authors: Mitchel W. C. , Park J. H. , Smith Howard E. , Grazulis L. , Mou S. , Tomich D. , Eyink K. , Elhamri Said 
Published: September 2011

ABSTRACTDirect deposition of graphene from carbon sources on foreign substrates without the use of metal catalysts is shown to be an effective process with several advantages over other growth techniques. Carbon source molecular beam epitaxy (CMBE) in particular provides an additional control parameter in carbon flux and enables growth on substrates other than SiC, including oxidized Si and sapphire. CMBE using thermally evaporated C60 and a heated graphite filament on SiC is reported here. The graphene films were characterized by Raman spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy and Hall effect. Graphene films on Si-face SiC grown using the C60 source have Bernal-like stacking and n-type conduction while those grown using the graphite filament have turbostratic stacking and p-type conduction. The sheet concentration for both n- and p-type doping is linearly dependent on film thickness.
Room Temperature Superparamagnetism observed in Foam-like Carbon Nanomaterials
Authors: Bandow Shunji , Asano Hirohito , Muraki Susumu , Mizuno Takahiro , Jinno Makoto , Iijima Sumio 
Published: September 2011

ABSTRACTMagnet-attractive carbon nanopowder can be produced by a pulsed Nd:YAG laser (10 Hz) vaporization of pure carbon in a few % of H2 containing Ar gas at 1000°C. On the other hand, magnet-attractive nanopowder cannot be formed when vaporizing in pure Ar. As-grown carbon nanopowder includes a few to ten % of micron sized graphite flakes as the impurity. Removal of such flakes can be achieved by a centrifugal separation and the supernatant is checked by X-ray diffractometry (XRD) and transmission electron microscopy (TEM). Magnetization curve at 400 K is easy to saturate at low magnetic field of 10 kG, and no hysteresis is observed. This feature is explained by a superparamagnetism of finely dispersed ferro- or ferri-magnetic nanoparticles. Elementary analyses using electron energy loss spectroscopy (EELS) and atomic absorption spectroscopy (AAS) suggest that the observed strong magnetism should be an intrinsic carbon magnetism.
A fully automated remote controllable microwave-based synthesis setup for colloidal nanoparticles with integrated absorption and photoluminescence online analytics
Authors: Einwächter Simon , Krüger Michael 
Published: September 2011

ABSTRACTWe present a fully automated microwave-based synthesis setup for colloidal nanoparticles. Integrated absorption and photoluminescence online analytics opens the possibility to monitor the growth of various nanoparticles at any stage of the reaction. Spectroscopic investigation within the first seconds of a reaction is accessible opening the possibility to detect potential critical size nuclei as a function of the reaction conditions. Beside the possibility to perform systematic mechanistic studies, this system allows a high degree of synthesis control leading to very good product reproducibility. In conjunction with an automated auto sampler unit systematic multiple reactions can be performed one after each other and compared. The setup is remote-controllable allowing worldwide online control accessibility over the synthesis setup including data processing, visualization and storage. The performance of the setup will be demonstrated by using the synthesis of CdSe nanocrystals as a model system and can be extended to the synthesis of various metallic and semiconducting nanoparticles.
In Vitro Behavior and Design of a New Type Implant with Nanostructured Surface
Authors: Rosca J.C. Mirza , Raducanu D. , Martin D. Gonzalez , Lorente J.A. Garcia , Vasilescu C. 
Published: September 2011

ABSTRACTThis study was aimed to investigate in vitro and in vivo behavior of a Ti6Al7Nb biomaterial with a nanostructured HA-type coating and also the design and realization of a new special knee implant together with a selection of a suitable animal model for preclinical experimentation of the implants.The metallic material used like substrate alloy for layer deposition was a Ti6Al7Nb alloy obtained by double electron beam melting furnace. In order to obtain a nano-crystalline HA-coating first sodium titanate layer was obtained on the surface and then the implant was immersed in Ringer solution with additional PAW1 biovitroceramic (particles under 20 μm). Different deposition times (5, 10 and 19 days) were employed. Microscopy analysis and corrosion tests of the implants relieves that the nanostructured HA layer after 19 days of immersion shows promising results as regarding the implant employ in preclinical experiments.After a complex design based on knee bone radiography there has been manufactured two different types of devices for the metallic implants: a metallic plate and a pin. Two plates and two pins were implanted in each animal.For in vivo experiments the chosen animal model was the mini-pig because of its strong chirurgical resistance and perfect anesthesia toleration. For the testing 10 animals were used for implantation and one for the control. When the plate is implanted the bone has to have a good blood supply after the cut in order to avoid bone to die. All experimented implants were maintained in the animal during six months and periodically inspected. No sign of infection or another problem were observed during this period.
Optical and Spectroscopic Ellipsometric Study of Indium Boron Nitride Sputtered Thin Films with Low Boron Concentration
Authors: Ebdah Mohammad A. , Kordesch Martin E. , Ingram David C. , AlBrithen Hamad , Ibdah Abdel-Rahman A. , Cooper Kevin 
Published: September 2011

ABSTRACTAmorphous indium boron nitride (a-InBN) thin films were successfully fabricated using radio frequency (RF) magnetron sputtering, and were deposited onto fused silica and c-Si(100) substrates. Sputtering was achieved using a target of polycrystalline B and In species with B/In nominal at.% ratio of 25/75 under the flow of nitrogen. The structure and composition of the films have been investigated by X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), respectively. The XRD patterns reveal that the sputtered films are amorphous, and the XPS confirms the presence of boron in the films in addition to an oxide overlayer. The optical absorption of samples grown on silica was obtained using spectrophotometry (SP) technique in the wavelength range (200 - 800) nm. Analysis of the absorption coefficients using the Tauc linear extrapolation gives an optical bandgap of 2.05 eV, indicating a higher bandgap comparing to the measured optical bandgap of a-InN (1.25 eV) due to doping with boron. Films grown on c-Si(100) were characterized by spectroscopic ellipsometry (SE) technique in the wavelength range of (300-1700) nm. The measured ellipsometric spectra are described well by a two-layer model structure, which consists of a transparent layer on top of an absorbing layer. The thicknesses and optical functions of the transparent and absorbing layers were obtained by analyzing the measured ellipsometric spectra, Ψ and Δ within the framework of the Cauchy–Urbach (CU) and Tauc–Lorentz (TL) models, respectively. While the overlayer is completely transparent over the measured range (k(λ) = 0), the absorbing layer underneath it exhibits a clear absorption above its optical bandgap of 2.15 eV, which is in a good agreement with the SP finding. There was an excellent agreement between the bandgap obtained as a fitting parameter from the optical model and that obtained by linear extrapolation using the empirical Tauc and Cody models for amorphous semiconductors.
Plasma-Enhanced Metalorganic Chemical Vapor deposition of Lipon Thin Films
Authors: Meda Lamartine 
Published: September 2011

ABSTRACTLithium phosphorus oxynitride (Lipon) thin films have been deposited by a plasmaenhanced metalorganic chemical vapor deposition (PE-MOCVD) method using triethyl phosphate [(CH2CH3)3PO4] and lithium tert-butoxide [(LiOC(CH3)3] precursors. Growth rates were between 100 and 415 Å/min, and thicknesses ranged from 1 to 2.5 μm. X-ray powder diffraction showed that the films were amorphous, and X-ray photoelectron spectroscopy revealed approximately 6.9 at.% carbon in the films. The ionic conductivity of Lipon was measured using electrochemical impedance spectroscopy (EIS) and approximately 1.02 μS/cm was obtained, which is consistent with the ionic conductivity of Lipon deposited by radio frequency magnetron sputtering of Li3PO4 targets. An all-solid-state thin-film lithium microbattery such as Li/Lipon/LiCoO2/Au/substrate was successfully fabricated with Lipon deposited by PE-MOCVD. The battery has a capacity of ca. 22 μAh/cm2μm.
Li motion mechanisms in (Li,Na)3xLa2/3-xTiO3 (x = 0.067 and 0.167) series followed by ND, NMR and Impedance spectroscopy.
Authors: Varez A. , Rivera A. , Bucheli W. , Jimenez R. , Sanz J. 
Published: September 2011

AbstractThe dependence of Li mobility on structure and composition of quenched Li0.5-xNax La0.5TiO3 (0 ≤ x < 0.5) and slowly cooled Li0.2-xNaxLa0.6TiO3 (0 ≤ x < 0.2) perovskite series, has been investigated by means of Neutron Diffraction (ND), Nuclear Magnetic Resonance (NMR) and Impedance Spectroscopy (IS). The first series displays rhombohedral (√2ap, √2ap, 2√3ap; S.G. R-3c) symmetry and vacancies are randomly distributed on A-sites (disordered phases), while Li0.2-xNaxLa0.6TiO3 series, presents orthorhombic unit cells (2ap, 2ap, 2ap; S.G. Cmmm) and the vacancies are preferentially located in alternating layers along the c-axis (ordered phases). In both cases, Li ions are shifted from A sites to a fourfold coordination at unit cell faces of the single cubic perovskite and octahedral are tilted along the rombohedral axis in Li-rich and along b-axis in Li- poor series. By heating the elimination of the octahedral tilting takes place changing the symmetry from rhombohedral to cubic in Li-rich samples, and from orthorhombic to tetragonal in Li-poor samples; however no changes were detected in La-vacancy distributions. For a particular value of sodium content (x=0.3 for Li0.5-xNaxLa0.5TiO3 and x=0.17 for Li0.2-xNaxLa0.6TiO3), the conductivity drops several orders of magnitude indicating that the amount of vacancies approaches the percolation threshold. In the temperature range 77-500 K, conductivity of Na-doped samples displays departures from the Arrhenius behavior, decreasing activation energy from 0.37 to 0.25 eV in disordered samples and from 0.37 to 0.12 eV in ordered ones. The structural sites occupancy has been investigated by ND, while Li mobility was evaluated through NMR and Impedance spectroscopy. The temperature dependence of thermal BLi factors has been related to the increment of conductivity that precede structural transformations, suggesting that Li motion trigger detected transitions in both series.
Reconfigurable Graphene Logic Device Based on Tilted P-N Junctions
Authors: Tanachutiwat Sansiri , Lee Ji Ung , Wang Wei 
Published: September 2011

ABSTRACTIn this paper, we introduce a novel reconfigurable graphene logic based on graphene p-n junctions. In this logic device, switching is accomplished by using co-planar split gates that modulate the properties that are unique to graphene, including ambipolar conduction, electrostatic doping, and angular dependent carrier reflection. In addition, the use of these control gates can dynamically change the operation of the device, leading to reconfigurable multi-functional logic. A device model is derived from carrier transmission probability across the p-n junction for allowing quantitative comparison to CMOS logic. Based on this model, we show that the proposed graphene logic has significant advantages over CMOS gate in terms of area, delay, power, and signal restoration. Furthermore, the device utilizes a large graphene sheet with minimal patterning, allowing feasible integration with CMOS circuits, for potential CMOS-graphene hybrid circuits.
Nb-substituted TiO2 Nanosheet Exfoliated from Layered Titanate for photocatalysis
Authors: Song Haiyan , Sjåstad Anja O. , Norby Poul , Fjellvåg Helmer 
Published: September 2011

ABSTRACTPhotoelectrochemical behavior and Photocatalytic decomposition of Methylene Blue were studied on (Nb,Ti)O2 nanosheets electrode and (Nb,Ti)O2 particles produced from nanosheets, respectively. A detailed characterization of the materials show that Nb-substitution suppresses the transition from anatase to rutile. Depending on the oxygen partial pressure during the transformation, the Nb-substitution into TiO2 provokes different defect situations and also electronic properties. 1% Nb-substitution can drasticly increase the photocurrent and photocatalytic activity of Ti0.9O2 due to the formation of new defects and electron traps that can promote the separation of photoinduced holes and electrons. However, high concentration of electron traps produced by heavy Nb-doping can serve as efficient recombination centers that caused loss of photocatalytic activity of the samples.
On the Sol-gel Synthesis and Characterization of Titanium Oxide Nanoparticles
Authors: Chaudhary Varun , Srivastava Amit K. , Kumar Jitendra 
Published: September 2011

ABSTRACTTiO2 nanoparticles have been prepared by sol-gel process using titanium isopropoxide as a precursor with ethanol and water as solvents. The synthesis involves gel formation, digestion for 24h, drying at 100oC for 10h, and calcination in air at 500-800oC for 2h. The resulting powder has been studied with respect to phase(s), morphology, optical absorption and photo -luminescence (PL) behaviour. The calcination of dried sol-gel product at 500oC for 2h leads to formation of anatase phase that possesses a tetragonal structure (a = 3.785 Å, c = 9.514 Å, Z = 4), average crystallite size ~ 11 nm and band gap of 3.34 eV. Further, increasing the time (t) of calcination causes crystallite growth that follows the relation d = α – β exp (-t/τ), α = 18.1 nm, β = 9.6 nm and τ = 6.9h. However, calcination of sol-gel product at 800oC for 2h gives rise to a rutile phase (tetragonal a = 4.593Å, c = 2.959Å, Z = 2), average crystallite size ~ 25 nm and band gap of 3.02 eV. The anatase phase exhibits strong PL emission peaks (excitation wavelength 405 nm) at 2.06 and 1.99 eV due to defect levels within the energy band gap. This observation has been attributed to finite size effects occurring in nanoparticles.
Label Free DNA Detection Using Large Area Graphene-Based FET Biosensors
Authors: Guo Shirui , Lin Jian , Penchev Miroslav , Yangel Emre , Ozkan Mihrimah , Ozkan Cengiz S. 
Published: September 2011

ABSTRACTThis work describes the fabrication of highly sensitive graphene-based field effect transistor (FET) biosensors in a cost-effective way and its application in label-free DNA detection. CVD graphene was used to achieve mass production of FET device through photolithography method. Non-covalent functionalization of graphene with 1-Pyrenebutanoic acid succinimidyl ester ensures the high conductivity and sensitivity of the device. The present device could reach the low detection limit as low as 3*10-9 M.
Electrical Properties of Thin Layers Consisting of Surface Functionalized Silicon Nanoparticles
Authors: Nelles Jürgen , Rodríguez Castellón Enrique , Simon Ulrich 
Published: September 2011

ABSTRACTThe present study investigates systematically, how the electrical properties of thin films consisting of silicon nanoparticles are affected by an organic monolayer coating the particles. Therefore, films of as-prepared silicon nanoparticles with a size of about 23 nm as well as freshly etched ones, both terminated with hydrogen, are compared with films of silicon nanoparticles functionalized with different 1-alkenes. It is found that the activation energy of the electron transport through the nanoparticle films scales with the thickness and permittivity of the respective organic monolayer.
Fabrication of Rh-doped TiO2 nanofibers for Visible Light Degradation of Rhodamine B
Authors: Obuya Emilly A. , Harrigan William , O’Brien Tim , Andala Dickson , Mushibe Eliud , Jones Wayne E. 
Published: September 2011

ABSTRACTThe synthesis and application of environmentally benign, efficient and low cost heterogeneous catalysts is increasingly important for affordable and clean chemical technologies. Nanomaterials have been proposed to have new and exciting properties relative to their bulk counterparts due to the quantum level interactions that exist at nanoscale. These materials also offer enormous surface to volume ratios that would be invaluable in heterogeneous catalysis. Recent studies point at titanium dioxide nanomaterials as having strong potential to be applied in heterogeneous photocatalysis for environmental remediation and pollution control. This work reports the use of surface modified anatase TiO2 nanofibers with rhodium (Rh) nanoparticles in the photodegradation of rhodamine B (RH-B), an organic pollutant. The dimensions of TiO2 nanofibers were 150±50 nm in diameter and the size of the Rh nanoparticles was ~5 nm. The Rh-doped TiO2 catalyst exhibited an enhanced photocatalytic activity in photodegradation of rhodamine B under visible light irradiation, with 95 % degradation within 180 minutes reaction time. Undoped TiO2 did not show any notable phocatalytic activity under visible light.
Seeing through Corrosion: Using Micro-focus X-ray Computed Tomography and Neutron Computed Tomography to Digitally “Clean” Ancient Bronze Coins
Authors: Nguyen Hai-Yen , Keating Steven , Bevan George , Gabov Alexander , Daymond Mark , Schillinger Burkhard , Murray Alison 
Published: September 2011

ABSTRACTVast numbers of bronze coins have been, and continue to be, excavated from archaeological sites around the Greco-Roman world. While often of little value from a strictly numismatic point of view, these coins provide invaluable data within their respective stratigraphic contexts and are used to date occupational and architectural phases more precisely than by ceramics alone. Unfortunately, the build-up of corrosion and mineralization on these coins during their centuries of burial often obscures their legends. Rather than employing potentially destructive and time-consuming chemical or mechanical cleaning techniques to reveal these features, commercially available Micro-focus X-Ray CT systems are now sufficiently well developed to reveal original surface features and to permit identification by a trained numismatist without any cleaning at all.
THIN FILM SILICON SOLAR CELLS UNDER MODERATE CONCENTRATION
Authors: van Dam L.M. , van Sark W.G.J.H.M. , Schropp R.E.I. 
Published: September 2011

ABSTRACTThere are only very few reports on the effects of concentration in thin film silicon-based solar cells. Due to the presence of midgap states, a fast decline in fill factor was observed in earlier work. However, with the advent of more stable and lower defect density protocrystalline silicon materials as well as high quality micro-/nanocrystalline silicon materials, it is worth revisiting the performance of cells with these absorber layers under moderately concentrated sunlight. We determined the behavior of the external J-V parameters of pre-stabilized substrate-type (n-i-p) amorphous and microcrystalline solar cells under moderate concentrations, between 1 sun and 21 suns, while maintaining the cell temperature at 25oC. It was found that the cell efficiency of both the amorphous and the microcrystalline cells increased with moderate concentration, showing an optimum at approximately 2 suns. Furthermore, the enhancement in efficiency for the microcrystalline cells was larger than for the amorphous cells. We show that the Voc’s up to 0.63 V can be reached in microcrystalline cells while FF’s only decrease by 9%. The effects have also been computed using the device simulator ASA, showing qualitative agreement.
Effect of Dynamic Bias Stress (AC) In Short-Channel (L=1.5μm) p-Type polycrystalline Silicon (poly-Si) Thin Film Transistors (TFTs) on the glass substrate
Authors: Choi Sung-Hwan , Mo Yeon-Gon , Han Min-Koo 
Published: September 2011

ABSTRACTWe have investigated the stability of short channel (1.5μm) p-Type polycrystalline silicon (poly-Si) Thin Film Transistors (TFTs) on the glass substrate under AC bias stress. The variation of threshold voltage in short channel poly-Si TFT was considerably higher than that of long channel poly-Si TFT. Threshold voltage of the short channel TFT was considerably moved to the positive direction during AC bias stress, whereas the threshold voltage of a long channel was rarely moved. The variation of threshold voltage in the short channel p-type TFT under AC bias stess was more compared to that under DC bias stress. The threshold voltage of short channel (L=1.5μm) poly-Si TFT was increased about -7.44V from -0.305V to -7.745V when VGS = 5 (base value) ~ -15V (peak value), VDS = -15V was applied for 3,000 seconds. This positive shift of threshold voltage and significantly degraded s-swing value in the short channel TFT under dynamic stress (AC) may be due to the increase of the stress-induced trap state density at gate insulator / channel interface region.
Mixed phase silicon oxide layers for thin-film silicon solar cells
Authors: Cuony Peter , Alexander Duncan T.L. , Löfgren Linus , Krumrey Michael , Marending Michael , Despeisse Mathieu , Ballif Christophe 
Published: September 2011

ABSTRACTLower absorption, lower refractive index and tunable resistance are three advantages of doped silicon oxide containing nanocrystalline silicon grains (nc-SiOx) compared to doped microcrystalline silicon, for the use as p- and n-type layers in thin-film silicon solar cells. In this study we show how optical, electrical and microstructural properties of nc-SiOxlayers depend on precursor gas ratios and we propose a growth model to explain the phase separation in such films into Si-rich and O-rich regions as visualized by energy-filtered transmission electron microscopy.