bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal stability of magnetite (Fe3O4) nanoparticles
Authors: Ong B.H. , Devaraj N. K. , Matsumoto M. , Abdullah M. H. 
Published: August 2010

ABSTRACTMagnetite (Fe3O4) nanoparticles are prime candidates for biomedical applications due to their biocompatibility and good magnetic properties. However, magnetite is highly susceptible to oxidation when exposed to the atmosphere. In order to preserve their properties, it is important for the particles to maintain their magnetite phase. In this study, magnetite nanoparticles were prepared using the conventional co3precipitation of ferrous (Fe2+) and ferric (Fe3+) chloride salt solutions with sodium hydroxide (NaOH). Thermogravimetric analysis (TGA) was subsequently carried out to identify the transition temperatures. Energy Dispersive X3Ray (EDX) spectrum shows the presence of impurities, such as sodium (Na) and chloride (Cl) ions in the as3synthesized magnetite nanoparticles. The as3synthesized samples were then calcined in a chamber furnace according to TGA data. The calcined samples were next characterised by X3ray Powder Diffraction (XRD), Transmission Electron Microscopy (TEM) and Vibrating Sample Magnetometer (VSM) to determine the changes in phase and magnetic properties of the nanoparticles as a function of different calcination temperatures.
Magnetic and Transport Properties of Ni Doped Pr0.5Ca0.5Mn1-xNixO3-δ
Authors: Damari L. , Pelleg J. , Gorodetsky G. , Korn C. , Markovich V. , Shames A. , Wu X. , Mogilyansky D. , Fita I. 
Published: August 2010

ABSTRACTStructural, magnetic and transport properties of Pr0.5Ca0.5Mn1-xNixO3 (x =0, 0.04, 0.07, 0.1) series have been investigated. The substitution of Mn ions by Ni induces drastic changes in the magneto-transport properties of Pr0.5Ca0.5MnO3. The physical behavior depends drastically on O stoichiometry. For the low Ni doping x=0.04, 0.07, spin glass configuration is rather favored than ferromagnetism; while for x=0.10, the ferromagnetic phase is significantly suppressed. Pronounced irreversibility between zero-field cooled (ZFC) and field cooled (FC) magnetization and a kink in the ZFC curve observed for x=0.04 and 0.07 are indicative of spin-glass-like state. Applied hydrostatic pressure of about 10 kbar reduces the temperature of charge ordering in an x=0 sample by about 10 K indicating a pressure induced suppression of the Jahn-Teller distortions and of the electron-phonon coupling. Electron magnetic resonance (EMR) unambiguously evidences appearance of FM phase in Ni doped manganites. Temperature dependence of EMR spectra parameters allow us to speculate on the effect of magnetic inhomogeneities.
Fluorite and Pyrochlore Phases in the HfO2 -La2O3 -Gd2O3 Systems: Characterization and Calorimetric Study of Samples Quenched From Melts Formed by Laser Heating and Aerodynamic Levitation
Authors: Ushakov Sergey V. , Navrotsky Alexandra , Tangeman Jean A. 
Published: August 2010

AbstractNew experimental results on pyrochlore and defect fluorite phases in HfO2-La2O3 and HfO2-Gd2O3 systems are summarized. Fluorite Hf0.5Gd0.5O1.75 was formed by containerless melting and quenching. Melts with 25-65 mol% La2O3 did not produce any fluorite-type phases, but pyrochlores with cell parameters 10.74 to 10.86 Å. The fluorite phase of Hf0.5La0.5O1.75 can be formed on crystallization of an amorphous precursor from aqueous precipitation. Both La- and Gd- fluorite phases transform to ordered pyrochlore on annealing at 1450 °C. The enthalpies of formation from oxides are −107 ±5 kJ/mol for Hf2La2O7 and −49 ±5 kJ/mol for Hf2Gd2O7 as measured by high-temperature solution calorimetry. Further experiments are needed to elucidate the nature of stabilization of fluorite phase in thin films and powders. Occurrence of disordered phases in thin films, nanoparticles and radiation damaged materials is discussed.
Study of defects and structural transformations induced by ion irradiation of Y2O3 thin films deposited by Ion Beam Sputtering
Authors: Lacroix Bertrand , Paumier Fabien , Jublot Michael , Pacaud Jérôme , Gaboriaud Rolly J. 
Published: August 2010

AbstractY2O3 thin films deposited by Ion Beam Sputtering (IBS) deposition technique exhibit a particular disordered microstructure. In order to obtain a better knowledge on phase transition mechanisms occurring during irradiation, thin films with different microstructures have been implanted with xenon ions at different energies and different doses. This work established two types of transition (cubic-amorphous or cubic-monoclinic) depending mainly on the ion energy with a possibility to control the damaging kinetic via the pre-existing oxygen disorder.
Effects of Ion Irradiation on the Microstructure of an ODS/Fe12Cr Alloy
Authors: Castro V. de , Lozano-Perez S. , Jenkins M. L. 
Published: August 2010

ABSTRACTThis study describes the microstructures of an ODS/Fe12Cr alloy before and after Fe+ irradiation at 500°C to a dose of 2.5 dpa and compares these microstructures with those of a reference Fe12Cr alloy produced following the same pulvimetallurgical route. The grain and dislocation structures of the alloys did not seem to change after irradiation. The main difference after irradiation was the appearance of small loops, which had similar sizes, distribution and densities in the ODS and reference alloys. The size distributions and chemical compositions of the ODS particles were similar to those found before irradiation.
Effect of growth rate on microstructure and microstructure evolution of directionally solidified Nb-Si alloys
Authors: Sekito Yoshihito , Miura Seiji , Ohkubo Kenji , Mohri Tetsuo , Sakaguchi Norihito , Watanabe Seiichi , Kimura Yoshisato , Mishima Yoshinao 
Published: August 2010

AbstractIn the present work, Nb-18.1Si-1.5Zr alloy rods are produced with a growth rate ranging from 1.5 to about 1500 mm/h using the optical floating zone (OFZ) furnace. A part of each specimen is heat-treated at 1650 oC for 100 h. The microstructure was observed using SEM and TEM and analyzed using EPMA and EBSD.Eutectic-cells are observed in as-grown specimens with a growth rate of 150 mm/h or higher. It is found by EBSD analysis that the solidification direction of Nb is along <113> and that of Nb3Si is along <001], and {112} of Nb and {110) of Nb3Si are parallel. The present crystallographic orientation relationship between Nb and Nb3Si is different from that found in previous reports by several researchers. It was also confirmed that the heat-treated microstructure in the specimen grown by OFZ with a growth rate of 150 mm/h is similar to that in the heattreated specimen prepared by arc-melting.
Erbium Alloyed Aluminum Nitride Films for Piezoelectric Applications
Authors: Kabulski A. , Pagán V. R. , Korakakis D 
Published: August 2010

AbstractAluminum nitride (AlN) films have been explored for sensor and actuator applications, but the resultant piezoelectric coefficient is still too low to make the films more competitive with more commonly used piezoelectric materials such as lead zirconate titanate (PZT). While AlN does have the disadvantage of a lower piezoelectric response, it does have the ability to maintain its piezoelectric properties above 400°C, something that is not possible with other piezoelectric materials. It is desirable to achieve a larger piezoelectric response for AlN in order to facilitate the integration of nitride based devices into existing technologies but conventional methods of improving the response by growing higher quality film only result in slight improvements in the piezoelectric response. A method of improving the d33 piezoelectric coefficient beyond any values found in literature may be possible by exploring methods of improving PZT films.Rare earth doping has been reported to improve the piezoelectric properties of PZT resulting in significant increases in the piezoelectric coefficient. Research has been conducted using rare earth dopants to improve upon the optical properties of AlN, but the impact on piezoelectric effect has never been considered.Thin, 250-1000 nm, AlN:Er films have been reactively sputtered using erbium (Er)/aluminum alloyed targets to explore any improvement in piezoelectric properties of the AlN:Er films as compared to AlN films. AlN films with 0.5 and 1.5% Er concentrations have been found to have piezoelectric coefficients that are larger than comparable ‘Er-free’ AlN films. AlN films with only 0.5% Er quantities were found to increase the d33 coefficient compared to a similar AlN film depending on the thickness of the film. This increase results in d33,f values greater than 7pm/V which is larger than most values found in literature. By increasing the Er content to 1.5%, values of d33,f were found to be as large as 15 pm/V. This enhanced piezoelectric response is still lower than that of PZT, but can be used to create superior actuator devices than that of typical AlN films.
Ferroelectric Random Access Memory as a Non-Volatile Cache Solution in a Multimedia Storage System
Authors: Jung Dong Jin , Kim Kinam 
Published: August 2010

AbstractWe demonstrate that ferroelectric memory is very eligible to become a non-volatile cache solution, in particular, in a multimedia storage system such as solid-state disk. It could provide benefits both of performance and of reliability. In performance, a FRAM cache allows us to rid overhead of power-off recovery. Random WRITE performance has been improved by 250%. In assertion of endurance, we investigate acceleration factors to evaluate cycle-to-failure of the ferroelectric memory both in device-level and in capacitor-level. What has been found is that ferroelectric memory cells have 6.0×1014 of the cycle-to-failure at the operational condition of 85 o C and 2.0V. This cycle-to-failure is well above lifetime READ/WRITE cycles of 9.5×1013 in such system. From 2-dimensional stress simulation, it has also been concluded that the number of dummy cells plays a critical role in qualifying the high temperature life tests.
Piezoelectric Response of Lanthanum Doped Lead Zirconate Titanate Films for Micro Actuators Application
Authors: Iijima Takashi , Lee Bong-Yeon , Fukuyama Seiji 
Published: August 2010

AbstractLa doped lead zirconate titanate (PLZT) films are prepared using a chemical solution deposition process. The effect of La substitution on the piezoelectric response was investigated to clear the possibility of the micro actuator application for the PLZT films. Nominal compositions of the 10% Pb excess PLZT precursor solutions were controlled like La/Zr/Ti= 0/65/35, 3/65/35, 6/65/35, and 9/65/35. These precursor solutions were deposited on the Ir/Ti/SiO2/Si substrates, and the thickness of the PLZT films was 2μm. 10 to 20- μm- diameter Pt top electrodes are formed with a sputtering and a photolithography process. The polarization- field (P-E) hysteresis curves and the longitudinal displacement curves were measured with a twin beam laser interferometer connected with a ferroelectric test system. With increasing La substitution amount, theP-Ehysteresis curves became slim shape, and remnant polarization (Pr) decreased. The hysteresis of the piezoelectric longitudinal displacement curves also decreased with increasing La substitution amount. The amount of the displacement under unipolar electric field showed a peak at La/Zr/Ti= 3/65/35. The calculated effective longitudinal piezoelectric constant (d33eff) is 129.2 pm/V at 3/65/35. This amount was relatively higher than that of PZT films at morphotropic phase boundary (MPB: 0/53/47) composition prepared the same film preparation process.
Potential of Hot Wire CVD for Active Matrix TFT Manufacturing
Authors: Schropp Ruud E.I. , Houweling Zomer Silvester , Verlaan Vasco 
Published: August 2010

AbstractHot Wire Chemical Vapor Deposition (HWCVD) is a fast deposition technique with high potential for homogeneous deposition of thin films on large area panels or on continuously moving substrates in an in-line manufacturing system. As there are no high-frequency electromagnetic fields, scaling up is not hampered by finite wavelength effects or the requirement to avoid inhomogeneous electrical fields. Since 1996 we have been investigating the application of the HWCVD process for thin film transistor manufacturing. It already appeared then that these Thin Film Transistors (TFTs) were electronically far more stable than those with Plasma Enhanced (PE) CVD amorphous silicon. Recently, we demonstrated that very compact SiNx layers can be deposited at high deposition rates, up to 7 nm/s. The utilization of source gases in HWCVD of a-Si3N4 films deposited at 3 nm/s is 75 % and 7 % for SiH4 and NH3, respectively. Thin films of stoichiometric a-Si3N4 deposited at this rate have a high mass-density of 3.0 g/cm3. The dielectric properties have been evaluated further in order to establish their suitability for incorporation in TFTs. Now that all TFT layers, namely, the SiNx insulator, the a-Si:H or μc Si:H layers, and the n-type doped thin film silicon can easily be manufactured by HWCVD, the prospect of “all HWCVD” TFTs for active matrix production is within reach. We tested the 3 nm/s SiNx material combined with our protocrystalline Si:H layers deposited at 1 nm/s in ‘all HW’ TFTs. Results show that the TFTs are state of the art with a field-effect mobility of 0.4 cm2/Vs. In order to assess the feasibility of large area deposition we are investigating in-line HWCVD for displays and solar cells.
Correlation Between On/Off Ratio and Electron Traps in Hole-Only Carbon-Nanotube-Enabled Vertical Field Effect Transistors
Authors: McCarthy Mitchell Austin , Liu Bo , Rinzler Andrew Gabriel 
Published: August 2010

AbstractSingle wall carbon nanotube enabled vertical field effect transistors (VFETs) are studied and the dependence of the on/off ratio on the relative number of electron traps is investigated. Current versus voltage measurements on several VFETs with varying interfacial trap densities in the vicinity of the nanotube network/polymer active layer junction are taken. It is found that the on/off ratio of the VFET changes from 1600 to 20 for typical operational currents as the onset gate voltage in the off-to-on transfer curve shifts from 94 V to 72 V. Such a strong dependence on trapped charge motivates future work to uncover the mechanism of charge trapping.
Formation and Electrical Interfacing of Nanocrystal-Molecule Nanostructures
Authors: Barrett Claire , Lévêque Gaëtan , Doyle Hugh , Lydon Donocadh P , Redmond Gareth , Spalding Trevor R , Quinn Aidan J 
Published: August 2010

AbstractThe formation of nanocrystal-molecule-nanocrystal nanostructures via controlled mixing of Au nanocrystals and bifunctional Re linkers is reported. UV-visible absorbance data, coupled with histogram analysis of nanostructures measured using Scanning Electron Microscopy has shown a characteristic optical response at wavelengths close to 600 nm following formation of dimer and trimer nanostructures. Directed assembly processes based on dielectrophoretic trapping have also been developed for electrical interfacing of these nanostructures between top-down nanoelectrode pairs for electrical characterization.
Application of UV Irradiation in Removal of Post-etch 193 nm Photoresist
Authors: Le Quoc Toan , Kesters Els , Prager L , Lux Marcel , Marsik P , Vereecke Guy 
Published: August 2010

AbstractThis study focused on the effect of UV irradiation on modification of polymethyl methacrylate-based photoresist, and then on wet photoresist (PR) removal of patterned structure (single damascene structure). Three single-wavelength UV sources were considered for PR treatment, with λ = 172, 222, and 283 nm. Modification of blanket PR was characterized using Fourier-transform infrared spectroscopy (FTIR; chemical change), spectroscopic ellipsometry (SE; thickness change), and dissolution in organic solvent (solubility change). While for patterned samples, scanning electron microscopy (SEM) was used for evaluation of cleaning efficiency. In comparison to 172 nm, the PR film irradiated by 222 nm and 283 nm photons resulted in formation of higher concentration in C=C bond. Immersion tests using pure N-methyl pyrrolidone (NMP) at 60 °C for 2 min showed that some improvement in PR removal was only observed for PR films treated by 283 nm UV for short irradiation times. Irradiation by photons at the other two wavelengths did not result in an enhancement of removal efficiency.The PR film treated by 222 nm photons was chosen for further study with O3/H2O vapor at 90°C. Experimental results showed a complete PR and BARC removal for UV-treated PR, which can be explained by C=C bond cleavage by the oxidizer.
VSS-induced NiSi2 Nanocrystal Memory
Authors: Li Bei , Liu Jianlin 
Published: August 2010

AbstractNiSi2 nanocrystals were synthesized and used as the floating gate for nonvolatile memory application. Vapor-solid-solid mechanism was employed to grow the NiSi2 nanocrystals by introducing SiH4 onto the Ni catalysts-covered SiO2/Si substrate at 600°C. The average size and density of the NiSi2 nanocrystals are 7∼10nm and 3×1011 cm-2, respectively. Metal-oxide-semiconductor field-effect-transistor memory with NiSi2 nanocrystals was fabricated and characterized. Programming/erasing, retention and endurance measurements were carried out and good performances were demonstrated.
Development of Novel Multiferroic Composites Based on BaTiO3 and Hexagonal Ferrites
Authors: Karpinsky D. V. , Selezneva E. K. , Bdikin Igor , Figueiras F. , Kamentsev K. E. , Fetisov Yuri , Pullar R. C. , Krebbs J. , Alford N. M. , Kholkin A. L. 
Published: August 2010

AbstractA new multiferroic composite ceramics with the general formula (x)Ba(Sr)Fe12O19-(1-x)BaTiO3 (x=0.1, 0.5) was synthesized via a simple solid-state reaction technique. Crystal structure analysis performed for both materials revealed the presence of two crystalline phases pertinent to the initial composite components. X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to testify the crystallinity, microstructure, and local magnetoelectric interactions between ferroelectric and ferromagnetic grains. Magnetic measurements revealed that the saturation magnetization is proportional to the volume fraction of ferrite phase. Dielectric studies demonstrated strong frequency relaxation due to space charge polarization and high conductivity loss making macroscopic magnetoelectric measurements difficult. Novel nanoscale magnetoelectric effect observed by AFM is discussed.
Sharp Absorption and High Temperature Thermal Emission from Simple Metallic Photonic Crystals
Authors: Biswas Rana , Zhou Dayu , Puscasu Irina , Johnson Edward , Taylor Andrew , Zhao Weijun 
Published: August 2010

AbstractWe design and fabricate metallic photonic crystals with sharp absorption peaks in the infrared regime. We have fabricated a metallic photonic crystal consisting of a triangular lattice of holes in a silicon layer conformally coated with gold at a lattice pitch of 3.8 microns. Conventional lithographic and deep reactive ion etching was used. The photonic crystal exhibits a deep reflection minimum and sharp thermal emission peak near the lattice spacing. Measurements agree well with rigorous scattering matrix simulations. This simple single-layer structure with a single patterned exposure has no emission sidebands and can be scaled to other lattice spacings.
Impurity Study of Optical Properties in Fluorine-Doped Tin Oxide for Thin-Film Solar Cells
Authors: Li Xiaonan 
Published: August 2010

AbstractTin oxide (SnO2) is a durable, inexpensive transparent conducting oxide (TCO) material used for thin-film photovoltaic devices. However, the optical properties of conducting SnO2:F are generally not as good as in other conducting TCO materials such as ITO and ZnO:Al. Our previous analyses indicate that for thin-film solar cells, improving the optical properties of SnO2-coated glass could enhance photon collection and gain up to 10% additional photocurrent. Previously, we showed that some commercial SnO2 samples could have much higher optical absorption than others [2]. In this work, we continue our study on causes that could contribute to the high optical absorption of SnO2 films. The SnO2:F samples are fabricated by low-pressure metal-organic chemical vapor deposition or atmospheric-pressure chemical vapor deposition with tin precursors that includes different amounts of chlorine. Optical, electrical, and compositional analyses were performed. In addition to the free-carrier-introduced optical absorption, the non-active dopant also impacts the optical absorption. Among the SnO2 films fabricated with different precursors, the optical properties show a relationship based on the level of chlorine in the precursors and films. With a low-optical-absorption SnO2 layer, the solar cell could have better photon collection and a higher short-circuit current density.
Long-Term performance of a commercial Thermoelectric Power Generator
Authors: Hatzikraniotis Euripides , Zorbas Konstantinos , Kyratsi Theodora , Paraskevopoulos Konstantinos M 
Published: August 2010

AbstractIn this work, thermoelectric device was made, using a commercially available ThermoElectric Generator (TEG), in order to measure the gained power and efficiency for long-term performance. The module was subjected to sequential hot side heating at 200°C (392 0F), and cooling for 6000 cycles, in order to measure the TEG's power and EMF change. A 14% increase in the TEG’s material resistance was found, as well as a 5% reduction in the Seebeck coefficient. After the experiment, the module was disassembled and thermoelectric p- and n- legs were examined using IR spectroscopy.
InGaP Layers Grown on Different GaAs Surfaces for High Efficiency Solar Cells
Authors: Martínez Oscar , Hortelano Vanesa , Parra Vicente , Jimenez Juan , Prutskij Tatiana , Pelosi Claudio 
Published: August 2010

AbstractInGaP layers grown on non-polar and polar GaAs substrate faces are investigated by Raman spectroscopy, microphotoluminescence and cathodoluminescence. The growth on polar faces benefits disorder respect to the layers grown on non polar (001) faces. It is shown that both (111)Ga and (111)As faces result in disordered InGaP layers. However, the layers grown on (111)As faces present inhomogeneous composition. The layers grown on (111)Ga faces present homogeneous composition close to lattice matching and are almost disordered.
Structural, Optical and Luminescent Properties of ZnO:Eu3+ Nanocrystals Prepared by Modified Sol-Gel Method
Authors: Jauregui-Rosas Segundo R. , Perales-Perez Oscar , Tomar M. S. , Jia Wei-Ji , Vasquez O. , Angelats-Silva Luis 
Published: August 2010

AbstractHighly monodisperse ZnO:Eu3+ nanocrystals have been synthesized by modified sol-gel method from ethanolic solutions. The effect of Eu3+ ions (x=0.05-0.30) concentration on the structural, optical and luminescent properties has been evaluated. No other than the ZnO-wurtzite phase was observed at all dopant levels, which was confirmed by FT-IR and Raman spectroscopy techniques. A blue shift of the exciton peak and the increase on the corresponding band gap were observed at increasing Europium contents, which would indicate an interaction between Eu3+ ions and the development of the ZnO host structure. The luminescence properties were also dependent on Europium contents; a systematic blue shift and enhancement of the intensity of visible luminescence peak, attributed to an increment of surface defects, was observed by a rising Europium concentration. The red luminescence band, representing the 5D0→7F0 transition, was clearly observed in nanocrystals after annealing at 300OC for one hour. The presence of this band could be considered as an evidence of the effective energy transfer from ZnO to Eu3+ ions.