bluuebunny/crossref_metadata_2025_split huggingface dataset:
Degradation Studies of Colloidal Quantum Dot Light-Emitting
Diodes
Authors: Liu Jie , Xie Chuang , Zhang Yu , Hu Wenjia , Pickering Shawn , You Guanjun , Wang Andrew Y. , Xu Jian 
Published: April 2011

ABSTRACTThe degradation mechanism of CdSe/ZnS quantum dots (QDs) light-emitting
diodes (LEDs) was investigated with steady-state and time-resolved
photoluminescence measurements. Our study reveals that the degradation is
associated with the decreasing quantum efficiency of the CdSe/ZnS QDs in the
devices. Two mechanisms that cause the efficiency reduction were verified in
the experiments: i.e., thermal instability and luminescence quenching.
Design of Optical Isolator with TiO2/(CeY)3Fe5O12 Guiding Layer
Authors: Yokoi Hideki , Ikeya Shintaro , Imada Tsuyoshi 
Published: April 2011

ABSTRACTAn optical isolator with a TiO2/(CeY)3Fe5O12 guiding layer was studied. A nonreciprocal phase shift was calculated in the magneto-optic waveguide with the TiO2/(CeY)3Fe5O12 guiding layer at a wavelength of 1.55 μm. By employing a multimode interference coupler as coupling devices, the total device length of approximately 600 μm was achieved. An interferometric optical isolator with distinct layer structures, which could be operated in a unidirectional magnetic field, was also designed.
Polarization Dependence and Relaxation of the Current in Polycrystalline Ferroelectric Pb(ZrTi)O3 Film
Authors: Delimova L. A. , Yuferev V. S. , Ankudinov A. V. , Gushchina E. V. , Grekhov I. V. 
Published: April 2011

ABSTRACTUsing Scanning Spreading Resistance Microscopy and direct current-voltage measurements, a long-relaxation transport current in polycrystalline PZT films is shown to depend on the polarization direction and voltage rise rate, the latter is typical for a capacitive current. The clockwise current hysteresis is observed at any polarization of the film. We suppose that the long current relaxation is due to recharge of traps, which participate in screening of polarization charges on PZT grain boundaries. The polarization charges response to applied bias for a short time, whereas the traps response to variation of the polarization charges takes much longer time.
Ion Beam Irradiation-induced Amorphization in Nano-sized KxLnyTa2O7-v Tantalate Pyrochlore
Authors: Lu Fengyuan , Nyman May , Shen Yiqiang , Dong Zhili , Wang Gongkai , Zhang Fuxiang , Ewing Rodney , Lian Jie 
Published: April 2011

ABSTRACTThe radiation response of nano-sized tantalate pyrochlores, KxLnyTa2O7-v (Ln = Gd, Y, and Lu) with average grain sizes of ~ 10 nm was investigated using 1 MeV Kr2+ ion beam irradiations. EDS measurements and XRD refinement reveal that the Y3+ and Lu3+-doped samples consist of two pyrochlore phases as K0.8YTa2O6.9/K0.4Y0.8Ta2O6.4 and KLuTa2O7/K0.4Lu0.8Ta2O6.4 respectively; whereas a single phase of K0.8GdTa2O7 only exists in the Gd3+-doped tantalate pyrochlore. In situ TEM observation confirms ion beam-induced amorphization occurring in all of the nano-sized KxLnyTa2O7-v. At elevated temperatures, both K0.8GdTa2O7 and K0.8YTa2O6.9/K0.4Y0.8Ta2O6.4 exhibit higher radiation tolerance than KLuTa2O7/K0.4Lu0.8Ta2O6.4, and the critical temperatures of K0.8GdTa2O7 and K0.8YTa2O6.9/K0.4Y0.8Ta2O6.4 are estimated to be 1167 ± 41 K and 1165 ± 34 K, respectively, lower than that of KLuTa2O7/K0.4Lu0.8Ta2O6.4 (~ 1291 K). The K0.8GdTa2O7, K0.8YTa2O6.9 and KLuTa2O7 phases have less structural deviation from the parent fluorite structure and thus may be responsible for the overall radiation tolerance. The high K+ occupancy at pyrochlore A sites in KLuTa2O7 is believed to contribute to the decrease of radiation tolerance, consistent with the large ionic radius ratio of K+/Ta5+. These results highlight that the radiation tolerance of nanostructured materials is highly compositional dependent, and nano-sized tantalate pyrochlores are sensitive to radiation damage.
High Temperature Thermal Analysis of Graphite and Silicon Carbide with Millimeter-Wave Radiometry
Authors: Woskov Paul P. , Sundaram S. K. 
Published: April 2011

ABSTRACTMillimeter-wave thermal analysis instrumentation is being developed for characterization of high temperature materials required for diverse fuel and structural needs in extreme high temperature reactor environments. A two-receiver 137 GHz system with orthogonal polarizations for anisotropic properties resolution has been implemented at MIT and is being tested with graphite and silicon carbide specimens at temperatures up to 1300ºC. Real time measurement sensitivity to submillimeter surface displacement and simulated anisotropic surface emissivity is demonstrated.
FLUCTUATION OF INTERNAL FRICTION IN METALLIC GLASSES
Authors: Miyauchi Y. , Tamura R. , Hiki Y. 
Published: April 2011

AbstractInternal friction (IF) of a metallic glass Zr55Cu30Al10Ni5 has been measured near the glass transition temperature Tg (= 666 K). The measurement is performed by using DMA (TA Instrument) apparatus at a frequency of 0.01 Hz for a specimen stabilized by annealing. The specimen is kept at a constant temperature T, and the IF value Q-1 is measured as a function of time t. A fluctuation of Q-1 with time is seen, and the magnitude of the fluctuation, F(t), is derived from the Q-1-vs-t data. F(t) is Fourier transformed to the frequency spectrum F(f). Such experiment and analyses are carried out at various temperatures near Tg. A characteristic peak (f ~ 10-3 Hz) is found in the spectrum F(f) in the glass transition region.
Composition, Bonding state, and Electrical Properties of Carbon Nitride Films Formed by Electrochemical Deposition Technique
Authors: Kiyota Hideo , Higashi Mikiteru , Kurosu Tateki , Chiba Masafumi 
Published: April 2011

ABSTRACTComposition, bonding state, and electrical properties of CNx films formed by electro-chemical deposition using liquid acrylonitrile were studied. X-ray photoelectron spectra reveal that C, N, and O are major components of the deposited films. From analysis of C 1s and N 1s spectra, the major bonding state in the CNx film is attributed to a mixture of C≡N and partially hydrogenated C=N bond. Metal-insulator-semiconductor capacitors incorporating the CNx insulating layers are fabricated to evaluate the electrical properties of the deposited films. The lowest dielectric constant k of the CNx film is determined to be 2.6 from the accumulation capacitance and the thickness of the film. It is demonstrated that the CNx film formed by electrochemical deposition is a promising low-k material for use in ultralarge-scale integration multilevel interconnections.
Irradiation Damage in Dual Beam Irradiated Nanostructured FeCrAl Oxide Dispersion Strengthened Steel
Authors: Richter A. , Chen C.-L. , Mücklich A. , Kögler R. 
Published: April 2011

ABSTRACTAn oxide dispersion strengthened steel is produced which contains Y-Al-Ti-O nanoparticles with an average diameter of 21 nm. HRTEM analysis shows that the chemical composition of the Y2O3 oxide is modified with perovskite YAlO3 (YAP), Y2Al5O12 garnet (YAG) and Y4Al2O9 monoclinic (YAM) particles. Irradiation of these alloys was performed with a dual ion beam system operating simultaneously with 2.5 MeV Fe+ to 31 dpa and 350 keV He+ to 18 appm/dpa. Ion bombardment causes atomic displacements resulting in vacancy and self-interstitial lattice defects and dislocation loops. TRIM calculations for ODS steel indicate a clear spacial separation between vacancies and self-interstitials at which the vacancy distribution is close to the surface and the interstitials are deposited at a deeper position. The helium atoms mainly accumulate in the vacancies. Fine He cavities with diameters of a few nanometers were identified in HRTEM images. Additionally to structural changes, irradiation generated defects also affect the mechanical properties of the ODS steel. These were investigated by nanoindentation, which is a suitable measuring method as the irradiation damage is created within a thin surface layer. A clear hardness increase in the irradiated depth region was observed, which reaches a maximum close to the surface. This indicates the He condensation in the vacancy dominated region predicted by the simulations.
Post-Processing Electrospun Fibers
Authors: Schauer Caroline L. , Austero Marjorie S. , Toth Amanda C. 
Published: April 2011

ABSTRACTElectrospinning is an inexpensive and simple method of producing non-woven
fiber mats. Electrostatic forces are employed to produce the mats, which
intrinsically have larger specific surface to volume ratio and smaller pores
than traditional fibers. Fibrous mats are typically used in a wide variety
of industries such as filter media, tissue engineering, and sensors.
Chitosan, the N-deacetylated derivative of chitin, is
environmentally friendly, non-toxic, biodegradable, and anti-bacterial.
However, due to chitosan’s solubility in aqueous acids, it is electrospun
using trifluoroacetic acid (TFA). Modified chitosans, such as
carboxymethylchitosan, are currently under investigation as a means of
creating designed nanofibrous mats with specific chemistries. However,
typically an entirely new set of electrospinning conditions has to be
developed for each novel chemistry due to differences in solubility and
viscosity. In the present study, we have electrospun chitosan mats and
post-processed the fibers. Two different post-processing conditions were
employed. One post-production procedure, featuring vapor-phase
glutaraldehyde, effectively crosslinks the fiber mats utilizing a Schiff
base imine functionality. In another post-processing procedure, the as-spun
mats are solution-phase post-processed by chemically functionalizing the
mats with cyano, carboxylic acids and thiol groups. While both methods
maintained fiber shape and characteristics, there is a definite increase in
fiber diameters due to processing. FTIR, NMR, SEM and tensile testing have
been performed on the pre- or post-processed fiber mats. Investigations into
the percent modification are currently underway.
Magnetic properties of acrylic UV-cured films containing magnetite nanoparticles
Authors: Chiolerio Alessandro , Allia Paolo , Tiberto Paola , Suber Lorenza , Marchegiani Giada , Sangermano Marco 
Published: April 2011

ABSTRACTAcrylic based films containing thermo-chemically synthesized magnetite nanoparticles (NPs) were prepared by UV-curing. A stable dispersion of Fe3O4 NPs in n-hexane was added to polyethylene glycol diacrylate (PEGDA) oligomer or to hexanediol diacrylate (HDDA) oligomer, producing a blend whose viscosity matches the processing requirements for inkjet printing technology. Morphologic characterization is provided by means of Field Effect SEM on a representative nanocomposite section.By real-time FT-IR analysis it was shown that Fe3O4 NPs are able to initiate radical chain-grown polymerization under UV light, for what concerns the HDDA matrix. Tight cross-linked transparent polymeric films were obtained after 1 minute of UV irradiation.The magnetic properties of the produced films were studied by means of an Alternating-Gradient Force Magnetometer (AGFM) in the temperature range 10 – 300 K and up to 18 kOe. The isothermal magnetization curves of both HDDA and PEGDA -based nanocomposites showed that these hybrid systems must be described as interacting superparamagnets (ISP) characterized by inter-particle magnetic interactions dominating over intra-particle effects.
Magneto-Optic Indicator Films for Forensics
Authors: Krafft Charles , Tkachuk Sergiy , Lang Garrett , Bowen David , Mayergoyz Isaak. D. 
Published: April 2011

ABSTRACTGarnet films based on (BiPrGdLu) (FeGa) have been grown on (210) and (100) oriented SGGG substrates. (210) films with an easy plane of magnetization provided optimal imaging contrast. Incorporation of Au nanoparticles into an epitaxially grown film was done and these films show an increase in Faraday rotation, ostensibly due to the plasmon resonance effect.
All-Semiconducting Nanotube Networks: Towards High Performance Printed Nanoelectronics
Authors: Rouhi N. , Jain D. , Zand K. , Burke P. J. 
Published: April 2011

ABSTRACTIn this work, we present progress towards devices fabrication using all semiconducting nanotubes as the starting material. Individual nanotubes are known to have intrinsic mobility of more than 10,000 cm2/V-s but using a network of nanotubes will decrease this mobility because of tube-tube screening effect and junction resistance. Here we are using solution-based deposition of purified 99% semiconducting single-walled nanotubes as the channel in field effect transistors. DC analysis of devices’ characterization shows a high mobility, more than 50 cm2/Vs, and good on/off ratio in the range of more than 103 and 104. A critical issue is the ink formulation and dependence of electronic properties on the nanotube density after deposition. In addition, the channel length also plays an important role in controlling both mobility and on/off ratio.
Carbon nanofiber-based photonic crystals – fabrication, diffraction and ellipsometry investigations
Authors: Rehammar Robert , Magnusson Roger , Lassesson Andreas , Arwin Hans , Kinaret Jari , Campbell Eleanor 
Published: April 2011

ABSTRACTCarbon nanofibers were used as building blocks for two-dimensional photonic crystal slabs. Electron beam lithography and chemical vapor deposition were used to fabricate regular arrays and random patterns of nanofibers. The optical properties of the samples were investigated using a diffraction measurement setup, as well as reflection ellipsometry. We find that carbon nanofiber regularity has a strong effect on both diffractive and specular optical properties. This shows that ellipsometry can be a valuable tool to study properties of carbon nanofiber arrays. It also shows that carbon nanofibers provide an interesting candidate as building blocks for nanostructured optical components.
Size Effect on Bending Properties of Diamond-Like Carbon Nanopillar Fabricated by Focused Ion-Beam Assisted Chemical Vapor Deposition
Authors: Kogo Yasuo , Harada Hiroyuki , Shibutani Yoji , Sakamoto Naomichi , Yasuno Takuya 
Published: April 2011

ABSTRACTBending tests of Diamond-Like Carbon (DLC) nanopillars fabricated by Focused Ion-Beam assisted Chemical Vapor Deposition (FIB-CVD) were carried out in a scanning electron microscope (SEM) to investigate their mechanical behavior. Special attention was paid on the effect of the specimen size. The nanopillars with nano-sized diameter and micro-sized length were grown using spot irradiation without scanning FIB. The diameter of the nanopillars was changed in the range of 100 ~ 1000 nm by changing the magnitude of defocusing FIB.In the bending tests, brittle fracture was observed for the nanopillars with diameter of 1000 nm. On the contrary, large deformation without brittle fracture was confirmed in the specimens with diameter of 300 nm. In addition, the pillar recovered its original shape after unloading without any permanent deformation even after the large deformation.Transmission electron microscope (TEM) analysis revealed that the pillars had uniform amorphous structures regardless of the diameters if the FIB was defocused during processing. In addition, similar gallium (Ga) content and sp2/sp3 fraction were observed in both specimens. These results indicate that difference in microstructures cannot be the reason for that in mechanical behavior. In other words, it must be caused by the intrinsic size effect on the mechanical properties of DLC fabricated by FIB-CVD process.
Molecular Recognition Mechanisms of Calmodulin Examined by
Perturbation-Response Scanning
Authors: Aykut A. Ozlem , Atilgan Ali Rana , Atilgan Canan 
Published: April 2011

ABSTRACTWe analyze the apo and holo calmodulin (CaM) structures by sequentially
inserting a perturbation on every residue of the protein, and monitoring the
linear response. Residue crosscorrelation matrices obtained from 20 ns long
molecular dynamics simulation of the apo-form are used as the kernel in the
linear response. We determine two residues whose perturbation equivalently
yields the experimentally determined displacement profiles of CaM, relevant
to the binding of the trifluoperazine (TFP) ligand. They reside on
structurally equivalent positions on the N- and C-terminus lobes of CaM, and
are not in direct contact with the binding region. The direction of the
perturbation that must be inserted on these residues is an important factor
in recovering the conformational change, implying that highly selective
binding must occur near these sites to invoke the necessary conformational
change.
Thermo-Mechanical behavior at Nano-Scale and Size Effects in Shape Memory Alloys
Authors: San Juan Jose , Nó Maria L. , Schuh Christopher A. 
Published: April 2011

ABSTRACTShape Memory Alloys (SMA) undergo reversible martensitic transformation in response to changes in temperature or applied stress, exhibiting specific properties of superelasticity and shape memory. At present there is a high scientific and technological interest to develop these properties at small scale, to apply SMA as sensors and actuators in MEMS technologies. In order to study the thermo-mechanical properties of SMA at micro and nano scale, instrumented nano indentation is being widely used for nano compression tests. By using this technique, superelasticity and shape memory at the nano-scale has been demonstrated in micro and nano pillars of Cu-Al-Ni SMA. However the martensitic transformation seems to exhibit a different behavior at small scale than in bulk materials and a size effect on superelasticity has been recently reported. In the present work we will overview the thermo-mechanical properties of Cu-Al-Ni SMA at the nano-scale, with special emphasis on size effects. Finally, the above commented size effects will be discussed on the light of the microscopic mechanisms controlling the martensitic transformation at nano scale.
Strengthening effect of twin boundaries in bcc crystal evaluated through a micro-bending test
Authors: Karasawa Yuki , Mark Chang Tso-Fu , Shibata Akinobu , Sone Masato 
Published: April 2011

ABSTRACTIn the present study, the strengthening effect of nano-scale twins in body-centered cubic (bcc) crystal was evaluated using micro-sized cantilever type specimen which contained the nanotwinned region (midrib) in ferrous lenticular martensite. The SEM observations of the micro-sized specimen after bending deformation indicated that midrib can act as barriers against dislocations, resulting in slip localization and non-localization across midrib. The load-displacement curve obtained by bending test showed that twin boundaries significantly enhance the critical resolved shear stress of bcc.
Observation of Large, Anomalous Pyroelectric Response in AlN Thin Films
Authors: Crisman Everett , Vasilyev Vladimir , Drehman Alvin , Webster Richard 
Published: April 2011

ABSTRACTWe have observed a pyroelectric effect (PE) in reactively sputtered aluminum nitride (AlN) thin films that is typically a factor of twenty greater than commercial pyroelectric materials such as triglycine sulfate (TGS). This is most likely due to an extrinsic effect since the known crystalline structures of AlN are too symmetric to allow such high values for the PE response. Preliminary annealing studies support the assumption that residual strains remaining from the AlN thin film deposition are the most likely source of the anomalously high PE response. The results of these studies are presented along with some measurements that indicate a still higher PE response might be obtainable.
Piezoelectric Multimaterial Fibers
Authors: Chocat Noémie , Wang Zheng , Egusa Shunji , Ruff Zachary M. , Stolyarov Alexander M. , Shemuly Dana , Sorin Fabien , Rakich Peter T. , Joannopoulos John D. , Fink Yoel 
Published: April 2011

ABSTRACTHere we report on the design, fabrication, and characterization of fiber containing an internal crystalline non-centrosymmetric phase enabling piezoelectric functionality over extended fiber lengths [1]. A ferroelectric polymer layer of 30 μm thickness is spatially confined and electrically contacted by internal viscous electrodes and encapsulated in an insulating polymer cladding hundreds of microns in diameter. The structure is thermally drawn in its entirety from a macroscopic preform, yielding tens of meters of piezoelectric fiber. Electric fields in excess of 50V/μm are applied through the internal electrodes to the ferroelectric layer leading to effective poling of the structure. To unequivocally establish that the internal copolymer layer is macroscopically poled we adopt a two-step approach. First, we show that the internal piezoelectric modulation indeed translates to a motion of the fiber’s surface using a heterodyne optical vibrometer at kHz frequencies. Second, we proceed to an acoustic wave measurement at MHz frequencies: a water-immersion ultrasonic transducer is coupled to a fiber sample across a water tank, and frequency-domain characterizations are carried out using the fiber successively as an acoustic sensor and actuator. These measurements establish the broadband piezoelectric response and acoustic transduction capability of the fiber. The potential to modulate sophisticated optical devices is illustrated by constructing a single-fiber electricallydriven device containing a high-quality-factor Fabry-Perot optical resonator and a piezoelectric transducer.
Thermoelectric Properties of New Thallium Tellurides
Authors: Sankar Cheriyedath Raj , Bangarigadu-Sanasy Savitree , Kleinke Holger 
Published: April 2011

ABSTRACTTernary thallium chalcogenides of the formula Tl4MQ4, whereM= Zr and Hf andQ= S, Se, and Te were synthesized and characterized. Our X-ray diffraction studies on suitable single crystals reveal that the sulphides and selenides are isostructural, with monoclinic space groupP, whereas the corresponding tellurides crystallize in the rhombohedral crystal system (R). The structures of the sulphides and selenides are comprised of zigzag chains of edge-sharingMQ6octahedra, whereas theMTe6octahedra are interconnected via common faces to form linear trimeric units. In all cases, the atoms adopt common oxidation states, namely Tl+,M4+, andQ2–. The electronic structure calculations using the linear muffin tin orbital (LMTO) method predicted band gaps of 1.7 eV, 1.3 eV and 0.3 eV for the sulphides, selenides and tellurides, respectively, implying sulphides and selenides are large band gap materials, and the tellurides narrow gap semiconductors. Their electronic transport properties are also evaluated with respect to the thermoelectric energy conversion.
The observation of the lattice defect formation during hydrogenation and dehydrogenation in La(Ni,Sn)5 by in-situ positron lifetime measurement
Authors: Sakaki Kouji , Nakamura Yumiko , Shirai Yasuharu , Bowman Robert C , Akiba Etsuo 
Published: April 2011

AbstractTo clarify the effect of Sn substitution for Ni of LaNi5 on the lattice defect formation during the hydrogenation and dehydrogenation processes, in-situ positron lifetime measurements were per-formed in LaNi4.93Sn0.27. During the hydrogenation, the mean positron lifetime, τm, monotonically increased up to 175 ps which is almost same as calculated positron lifetime for vacancy. This shows vacancy introduction by hydrogenation. The τm mean positron lifetime decreased down to 135 ps with hydrogen content during the dehydrogenation. It shows that the vacancies are removed from the lattice during the dehydrogenation. These results show that vacancies in LaNi4.93Sn0.27 are intro-duced and removed reversibly during the hydrogenation and dehydrogenation. The concentra-tions of vacancy and dislocation were 1 × 10−5 and 6 × 109 cm−2, respectively. These values are two orders lower than those in LaNi5.