bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface Erosion of TiO2 subjected to Energetic Oxygen Bombardment
Authors: Smith Roger , Möller Wolfhard 
Published: April 2011

ABSTRACTThe effect of energetic oxygen bombardment of the TiO2 rutile {110} surface is studied by means of molecular dynamics simulations using a variable charge potential. A random selection of O atoms and O2 molecules are incident successively and normally onto the surface. At an energy of 5 eV the surface becomes saturated with oxygen until covered with between 1 and 2 monolayers of adatoms. As the fluence further increases Ti atoms are pulled out from the bulk and become surrounded by the O atoms forming well-defined atomic clusters on the surface which then desorb. At bombardment energies of 400 eV, the O atoms penetrate into the bulk and voids form whose surfaces are decorated with oxygen atoms. As the O fluence further increases the surface is sputtered and the voids then intersect the surface forming a very rough topography.
COMPARISON OF DEMINERALIZED AND DEPROTEINIZED BONE
Authors: Castro-Ceseña Ana B. , Novitskaya Ekaterina , Chen Po-Yu , Sánchez-Saavedra M. del Pilar , Hirata Gustavo , McKittrick Joanna 
Published: April 2011

ABSTRACTCortical and cancellous bones were demineralized and deproteinized using 1 N HCl and 6% NaOCl, respectively. Experiments were performed at 37°C. The rate constants were calculated and the structural features of untreated and completely demineralized and deproteinized samples were studied by scanning electron microscopy, showing that intact, contiguous structures were obtained. For both cases, the rate constant was higher for cancellous bone than the cortical bone.
Enhanced UV Photon-response of Tin Nano Cluster Loaded- laser Irradiated ZnO Thin film detector
Authors: Menon Rashmi , Sreenivas K. , Gupta Vinay 
Published: April 2011

ABSTRACTZinc Oxide (ZnO), II-VI compound semiconductor, is a promising material for ultraviolet (UV) photon sensor applications due to its attractive properties such as good photoconductivity, ease processing at low temperatures and excellent radiation hardness. The rf magnetron sputtering is a suitable deposition technique due to better control over stoichiometry and deposition of uniform film. Studies have shown that the presence of surface defects in ZnO and subsequently their passivation are crucial for enhanced photo-response characteristics, and to obtain the fast response speed. Worldwide efforts are continuing to develop good quality ZnO thin films with novel design structures for realization of an efficient UV photon sensor. In the present work, UV photon sensor is fabricated using a ZnO thin films deposited by rf magnetron sputtering on the corning glass substrate. Photo-response, (Ion/Ioff) of as-grown ZnO film of thickness 100 nm is found to be 3×103 with response time of 90 ms for UV intensity of 140 μW/cm2 (λ = 365 nm). With irradiation on ZnO thin film by pulsed Nd:YAG laser (forth harmonics 266 nm), the sensitivity of the UV sensor is found to enhance. The photo-response increases after laser irradiation to 4x104 with a fast response speed of 35 ms and attributed to the change in surface states and the native defects in the ZnO thin film. Further, enhancement in the ultraviolet (UV) photo-response (8×104) of detector was observed after integrating the nano-scale islands of Sn metal on the surface of laser irradiated ZnO thin film.
Effect of Different High-K Dielectrics on the Pt Nanocrystal Formation Statistics (size, density and area coverage) for Flash Memory Application
Authors: Misra Abhishek , Sadana Sunny , Suresh Satya , Bhaisare Meenakshi , Srinivasan Senthil , Waikar Mayur , Gaur Amit , Kottantharayil Anil 
Published: April 2011

ABSTRACTWe here present, metal nanocrystal (NC) formation statistics (size, density, occupancy or area coverage) on different high dielectric constant (high-K) materials which may be used as tunnel dielectric or intermetal dielectric in flash memory devices. Four important high-K materials viz. SiO2, Al2O3, HfO2 and Si3N4 are chosen for this purpose and the nanocrystal formation statistics has been found to be strongly dependent on dielectric. Among all the four dielectrics, smallest size nanocrystals with largest density are obtained on Al2O3 dielectric while on HfO2 bigger size nanocrystals are formed. This difference in nanocrystal size and density on different dielectrics is attributed to the different surface properties of these materials.
Electronic States and Magnetic Coupling in Fe/Fe3O4 Junctions
Authors: Inoue J. , Kida T. , Honda S. , Itoh H. , Yanagihara H. , Kita E. , Mibu K. 
Published: April 2011

ABSTRACTExchange coupling observed recently in Fe/ Fe3O4 (001) junctions shows comparable intensity to that in Co/Ru/Co trilayers, and has potential applicability to spintronics devices. To clarify the mechanism of the exchange coupling, electronic and magnetic states of Fe/ Fe3O4 junctions are calculated in the first principles method by assuming four junction structures of bcc Fe and Fe3O4 layers. It is shown that the local moments of bcc Fe atoms at the interface increase, but those of Fe ions at the interface of Fe3O4 layer decrease. The total energy of the junctions is plotted as a function of distance between Fe and Fe3O4 layers. Calculated results of the coupling energy between Fe and Fe3O4 layers, however, are larger than experimental ones by two orders of magnitude, and they correspond to inter-atomic exchange interactions at the interface. In order to explain the experimental results, we propose a mechanism of exchange coupling mediated by impurity-like states of interfacial Fe atoms which possess reversed magnetic moments in bcc Fe layer. Frustration effects in exchange coupling between Fe and Fe3O4 layers are also discussed.
Thermoplastic Wire Drawing from Bulk Metallic Glass
Authors: Bossuyt Sven , Soinila Erno , Penttinen Henri , Pulkki Ville , Hänninen Hannu 
Published: April 2011

ABSTRACTThe low loss coefficient and high elastic energy storage of amorphous metals may provide novel opportunities in the design of stringed musical instruments. To produce prototypes for metallic glass music wire, bulk metallic glass pre-forms were reheated into the supercooled liquid region and stretched into wires. Investigations of these wires’ geometrical, mechanical, and physical properties are reported. The process is relatively simple and could be practical for producing continuous wire. A theoretical analysis shows the importance of the interaction between heating power input, radiative and convective cooling, and area reduction in determining the wire’s final properties.
(CdSe) ZnS core shell quantum dots decorated zinc oxide nanowires for solar energy harvesting applications
Authors: Prasad Abhishek , Pandey Archana , Walczak Karl , Friedrich Craig , Yap Yoke Khin 
Published: April 2011

ABSTRACTZnO nanostructures have proven to be versatile functional materials with promising electronic, piezoelectric and optical properties. Here, we report on the application of (CdSe) ZnS Core Shell quantum dots decorated ZnO Nanowires (ZnONWs) and Nanobelts (NBs) in solar energy harvesting. Results indicate that both as grown and decorated ZnO Nanostructures are photoactive, have a fast response time and generate photocurrent under excitation in a photoelectrochemical cell setup. An order of magnitude enhancement in the photocurrent response of (CdSe) ZnS Core Shell quantum dots decorated ZnONBs is seen as compared to response from as grown ZnONBs. Generated photocurrent decreases with time but stabilizes at higher value for (CdSe) ZnS Core Shell quantum dots coated ZnONBs. Detailed performances of these devices are discussed.
A Study of Point Defects and Cause of Nonstoichiometry in InSb Nanowires
Authors: Philipose U. , Sapkota Gopal , Gali Pradeep , Nukala Prathyusha 
Published: April 2011

ABSTRACTSynthesis of InSb nanowires using chemical vapor deposition (CVD) is technically challenging due to the tuning of III-V vapor pressures. Growth parameters such as the choice of the metal catalyst, growth temperature and vapor pressure of constituents affect the morphology and stoichiometry of InSb nanowires. By controlling the growth temperature, it was possible to grow either stoichiometric InSb nanowires or In nanowires that contained no Sb within detectable limits. We present a simple model to show that the occurrence of native point defects in InSb is influenced by the growth kinetics and by the thermodynamics of defect formation. Results from this model are in good agreement with our experimental findings of the evidence of point defects in these nanowires.
The effect of Oxygen partial pressure during deposition in the magnetic properties of ZnO thin film
Authors: Biswas Anis , Shirong Wang , Nagar Sandeep , Belova L. , Rao K. V. 
Published: April 2011

ABSTRACTWe have studied the magnetic properties of 100 nm thick ZnO thin films prepared by magnetron sputtering in different oxygen partial pressures (ratio of oxygen pressure to total pressure in deposition chamber, POxy). Only the films fabricated at POxy below ~ 0.5 show room temperature ferromagnetism. The saturation magnetization at room temperature is initially found to increase as POxy increases and reaches maximum value of ~ 5 emu/gm at POxy ~ 0.3 and then starts to decrease and becomes diamagnetic for POxy > 0.5. From small angle XRD study of structural properties of the films, we find that the lattice stress developed in the film along c-axis also exhibits a similar behavior with the variation of POxy. Thus, both the room temperature ferromagnetism and lattice stress appear to originate from the intrinsic defects present in the sample.
Singlet Exciton Quenching by Radical Cations of Aromatic Diamines as an Electron Donor in Organic Electroluminescent Devices
Authors: Battulga Munkhbat , Bolormaa Gendensuren , Naranbileg Batjargal , Ganzorig Chimed 
Published: April 2011

ABSTRACTIn this study, we report the luminescence quenching by radical cations of aromatic diamines used as a hole transport layer (HTL) in organic electroluminescent (EL) devices. The EL characteristics of green organic EL devices with an electron transport layer (ETL) as an emitter i.e. ITO/TPD HTL/Alq3ETL/Al is studied. Here, ITO, TPD, and Alq3are abbreviations for indium-tin-oxide, N,N’-diphenyl-N,N’-bis(3-methylphenyl)-1,1’-biphenyl-4,4’-diamine, and tris (8-hydroxyquinoline) aluminum, respectively. UV-visible absorption and electrochemical data indicate the formation of radical cations in thin film and solution of TPD after chemical oxidation. We find that the EL luminance increases less than linearly with an increase in current for the EL devices studied in this study. The luminance loss in the devices is attributed to quenching of singlet excited states by large excess radical cations of TPD are accumulated in the emission zone due to large overlap between a flourescence spectrum of Alq3and an absorption spectrum of radical cations of TPD.
Electroluminescence Characteristics of Inorganic
(p-GaN/MgO)-Organic (Alq3) Hybrid p-n Junction Light Emitting
Diodes
Authors: Kikuchi Akihiko , Tsuji Tomoyuki 
Published: April 2011

ABSTRACTInorganic/organic hybrid light-emitting diodes (LEDs) (IO-HyLEDs) composed
of p-type GaN/n-type Tris-(8-hydoroxyquinoline) aluminum (Alq3)
were fabricated with and without thin MgO electron-blocking layer (EBL) at
the inorganic/organic interface. These LEDs showed clear and stable current
rectifying diode characteristics and electroluminescence (EL) peaked at UV
region at room temperature. For the sample with MgO-EBL, obvious enhancement
of green emission from Alq3 layer was observed. This result
suggests that due to effective suppression of electron transport from
Alq3 to p-GaN by MgO-EBL, radiative recombination of electrons
and holes in Alq3 layer was enhanced. It was indicated that the
band engineering technique can be applied to control the emission property
of inorganic/organic hybrid LED.
Stability of fast elaborated small CdS quantum
dots
Authors: Fregnaux M. , Dalmasso S. , Gaumet J.-J. , Laurenti J.-P. 
Published: April 2011

ABSTRACTSmall size CdS QDs were synthesized by (i) the single source precursor
methodology and by (ii) the microwave synthetic route. The consequences of
CdS QD direct exposure to air for a period of 7 days were investigated by
following the evolution of the photoluminescence (PL) and absortion spectra.
For QDs obtained by (i), the excitonic emission band (3.0 ‑ 3.1 eV)
decreases in intensity, relatively to the low energy one (2.2 ‑ 2.5 eV)
tentatively associated to midgap surface states. This suggests arising of
new recombination path(s) associated to degradations during aging, possibly
an oxidative formation of a CdO surface layer. On the other hand, no
significant change is observed in the absorption spectra. For QDs obtained
by (ii), no degradation is revealed by the PL spectra which remain
unchanged. On the other hand, the absorption spectra are dominated by an
unexplained broad band around 3.6 eV which tends to hide the fundamental
excitonic transition one and increases in intensity with aging.
Evidence of Conjugation Enhancement in P3HT/SWNT Mixtures for
Organic Photovoltaics
Authors: Bernardi Marco , Giulianini Michele , Motta Nunzio , Grossman Jeffrey C. 
Published: April 2011

ABSTRACTClassical molecular dynamics (MD) simulations in conjunction with optical
absorption and AFM/nano-Raman experiments are employed to relate the
molecular-scale arrangement and conjugation of poly-3-hexylthiophene (P3HT)
adsorbed onto single-walled carbon nanotubes (SWNTs) and multi-walled carbon
nanotubes (MWNTs). Taken together our results demonstrate the templating
role of carbon nanotubes in increasing the π-conjugation length of the P3HT
at the P3HT/carbon nanotube interface. The MD simulations show that SWNTs
and MWNTs, due to their inherent 1-dimensional (1D) cylindrical shape and
π-conjugation, planarize the P3HT molecules adsorbed at their surface and
thus quench their torsional disorder, regardless of the P3HT conformation
and nanotube chirality. This effect is more significant for higher SWNT
weight fractions in the sample (since it is an interface effect). We
investigated this effect experimentally by acquiring nano-Raman spectra in
regions of high-MWNT/low-P3HT content in addition to optical absorption
spectra of P3HT-SWNT composites with different SWNT concentrations . The
increase in the P3HT conjugation is confirmed by a shift of a P3HT feature
in the Raman spectrum when going from P3HT-rich to SWNT-rich areas in the
mixture. The significance of this work for charge transfer at the P3HT-SWNT
interface in bulk-heterojunction solar cells is discussed.
Charge transport in ambipolar pentacene thin film
transistors
Authors: Rahimi Ronak , Korakakis D. 
Published: April 2011

ABSTRACTAmbipolar organic transistors are technologically interesting because of
their potential applications in light-emitting field-effect transistors [1]
and complementary-metal-oxide-semiconductor (CMOS) devices by providing ease
of design, low cost of fabrication, and flexibility [2]. Although common
organic semiconductors show either n- or p-type charge transport
characteristic, organic transistors with ambipolar characteristics have been
reported recently. In this work, we show that ambipolar transport can be
achieved within a single transistor channel using LiF gate dielectric in the
transistors with pentacene active layer. This ambipolar behavior can be
controlled by the applied source-drain and gate biases. It was found that at
low source-drain biases multistep hopping is the dominant conduction
mechanism, while in high voltage regimes I-V data fits in Fowler-Nordheim
(F-N) tunneling model. From the slope of the F-N plots, the dependency
between field enhancement factor and the transition point in conduction
mechanism upon gate bias has been extracted. The transition points show more
dependency on gate voltage for negative biases compared to the positive
biases. While sweeping negative gate voltages from -5 to -20 V, the
source-drain voltages change from about 27 to 17 V. On the other hand, for
positive gate voltages from 5 to 20 V, the value of the transition point
stays at approximately 36 V. In order to further understand the transport
mechanisms, new structures with an interface layer between dielectric and
active layer have been fabricated and characterized. As expected, a
significant decrease in the amount of the source-drain current has been
observed after introducing the interface layer.
Magnetization Effects in bulk YFeO3 and their dependency on electric field strength and temperature as a basis for thin film investigation of Multiferroic Technology
Authors: Hinckley A. , Gupta R.K. , Kahol P.K. , Ghosh K. 
Published: April 2011

ABSTRACTMultiferroics, the study of materials which possess ferromagnetic and ferroelectric ordering in a single phase, has become an area of prominent research. Moreover, this behavior has been extensively studied in materials which possess a perovskite crystal structure such as BiFeO3 and YMnO3. Due to their weak saturation magnetic moment, many rare-earth orthoferrites are currently of extreme interest. Utilizing a solid-state reaction between Y2O3 and Fe2O3 we have developed the rare-earth orthoferrite YFeO3 and conducted a bulk material study to determine this material’s availability for thin film multiferroic research. The absence of Y2O3 and Fe2O3 impurities was confirmed using Copper-Kα XRD. Examination of the dependence of the magnetization M on the temperature T was conducted to determine the reliability of multiferroic behavior across varying temperatures in conjunction with the investigation of the dependence of M on the electric field strength H. Results clearly display ferromagnetic behavior in our bulk material, providing ample evidence that our bulk material is an excellent candidate for thin film studies. Future studies on multiferroic YFeO3 thin films grown via pulsed laser deposition on Lanthanum Aluminate substrates will be conducted. Detailed data will be provided via XRD and SQUID to confirm magnetic properties while impurities are non-existent in our thin films.
Alloying Effect of Ta on Microstructure and Mechanical Properties of Ni3(Si,Ti) Intermetallic Alloy
Authors: Imajo Daiki , Kaneno Yasuyuki , Takasugi Takayuki 
Published: April 2011

ABSTRACTThe refractory element Ta was added to L12-type Ni3(Si,Ti) intermetallic alloys in order to substitute for Ti. The microstructure and the mechanical properties of the alloys were investigated as a function of the Ta content. All the alloys were doped with 50 wt.ppm boron to suppress intergranular fracture. The alloys containing up to 5 at.% Ta showed an L12 single-phase microstructure, while the alloys containing more than 5 at.% Ta exhibited a two-phase microstructure consisting of Ni3Ta particles in the L12 matrix. At room-temperature (RT), the hardness of the alloys with the L12 single-phase microstructure increased with increasing Ta content due to solid solution hardening of Ta. RT yield stress (0.2% yield strength) and tensile ultimate strength of the alloys with the L12 single-phase microstructure increased with increasing Ta content keeping a high level of tensile elongation. At high-temperature (HT), the positive temperature dependence of hardness was observed in all the alloys, irrespective of Ta addition. HT hardness was also enhanced by the addition of Ta. It was consequently demonstrated that Ta is a remarkable solid solution hardening element in the Ni3(Si,Ti) alloys.
Indium Alloy as Cadmium Brush Plating Replacement
Authors: Berman Elizabeth , Brezovec Paul , Klingenberg Melissa , Naguy Thomas , Schmura Eileen , Voevodin Natasha 
Published: April 2011

ABSTRACTIt is well-known that cadmium and its corrosion product (cadmium oxide) are carcinogenic and toxic. Consequently, efforts to eliminate cadmium from original equipment and repair processes have been on-going. One potential replacement is indium, which is a soft post-transition metal, whose primary use is in the form of indium tin oxide, e.g., in liquid crystal displays (LCDs). The semi-conductive properties of indium oxide alloys make it possible to use these for cadmium brush plating replacement in applications where contact resistance and impedance are critical parameters. Critical requirements of an alternative to cadmium brush plating in a corrosive industrial atmosphere are (1) be sacrificial to mild steel and (2) provide good electrical conductivity. Cadmium oxide remains semi-conductive, while most other pure metal oxides are electrical insulators, such as aluminum oxide, nickel oxide, and zinc oxide, and therefore, fail in meeting the requirement for bonding and grounding. Similar to cadmium oxide, indium oxide is semi-conductive, but indium exhibits other properties such as cold welding. This paper discusses indium- electroplating approaches to overcome the insulating limitation of pure metal plating and to replace cadmium brush plating. Test results are given for the brush-plated indium-tin alloy as compared to cadmium brush plating and conclusions on such replacement feasibility are provided.
The ductility of cast TiAl-based alloys
Authors: Loretto M H , Wu Z. , Chu M Q , Hu D 
Published: April 2011

ABSTRACTThe factors which influence the ductility of cast samples of TiAl-based alloys are briefly reviewed with emphasis on alloys where microstructural refinement has been used in an attempt to improve ductility. The grain size in cast samples of different TiAl-based alloys can be refined either by high additions of about 1at% boron, or by lower additions of about 0.2at%. In addition it is possible to refine the microstructure by massively transforming samples and heat treating the transformed samples in the (alpha + gamma) phase field to precipitate alpha. Significantly different ductilities are found in different alloys with similar grain sizes or with similar microstructures and the origins of the improvements in ductility and of these differences are discussed in this paper. The role of alloying elements in influencing the degree of order in alpha 2 and in turn influencing slip in alpha 2 is discussed.
Low-damage Processing of Organic Materials with Size-controlled Gas Cluster Ion Beams
Authors: Nakagiri Motohiro , Toyoda Noriaki , Yamada Isao 
Published: April 2011

ABSTRACTOrganic materials have been widely used in various fields of electronic applications. However, they are difficult to process without damage by using a conventional ion beam which use energetic ions. In this study, gas cluster ion beam (GCIB), which shows low-damage process, was used for organic materials, and irradiation effect of size selected GCIB was studied with Xray photoelectron spectroscopy (XPS). In the case of irradiation of 500 eV Ar ion (monomer ion) on polyimide, the intensities of both N-C=O and C-O bond decreased after irradiation. On the other hand, there was small change in the XPS spectra after 15 keV Ar-GCIB irradiation with the same ion dose. The etching rate of polyimide per one ion with 15 keV Ar-GCIB was almost 1.8×104 times higher than that with 500 eV Ar monomer ions. The damages in polyimide decreased with increasing the Ar cluster size owing to the reduction of energy per atom at acceleration voltage of 15 kV. After irradiation of size selected 5 kV Ar cluster ion, damage was almost negligible. Although, the surface became rough after irradiation of Ar-GCIB, surface roughness and the change of chemical bond were very small with N2-GCIB irradiation. Ar-GCIB irradiation on dye-sensitized solar cells (N719) showed that very low-damage process is possible with GCIB, and it indicated that GCIB is suitable for surface processing of organic materials used in electronic devices.