bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electro-Optic and Magneto-Optic Photonic Bandgap Materials Kevin
Authors: Zou Y. , Wang Yanyun , Li Kewen , Jiang Hua , Mondal Samir K. , Hills Bethanie J. 
Published: April 2011

ABSTRACTThis work presents a study of electro-optic and magneto-optic films made by a Metal-Organic Chemical Liquid Deposition (MOCLD) method. Electro-optic thin film, La-modified Pb(Mg1/3Nb2/3)O3-PbTiO3 (PLMNT) and magneto-optic thin film, rare earth doped yittrium iron garnet (YIG) have been grown at different conditions. Low temperature growth on buffered semiconductor substrates has been studied for semiconductor device integration. High quality PLMNT film with EO coefficient of 1x10-16 (m/V)2 was obtained with MOCLD. Doped and undoped YIG onto MgO and glass substrates and also onto buffered semiconductors were successfully deposited using MOCLD method. Several of these films had successful rotations that were of device quality. Based on these high quality functional films, two dimensional photonic bandgap waveguide structures were designed and simulated.
Superprism effect in magneto-photonic crystals
Authors: Vinogradov A. P. , Merzlikin A. M. , Granovsky A. B. , Inoue M. , Khanikaev A. B. 
Published: April 2011

ABSTRACTIn frame of computer simulation we study for the first time the magnetic superprism effect. We employ a simple square lattice model and restrict ourselves to lossless case. The photonic band structure for 2D PC built up of magneto-optical matrix with square holes is calculated. It is shown that an external magnetic field applied perpendicularly to the holes changes 2D PC band structure and thus propagation of light through PC.The effect exists even for a weak magneto-optical activity of the matrix but only for the definite set of model parameters. Thus, it makes possible to deflect a light beam by applying magnetic field without variation of frequency or initial angle of incidence.
Three-Dimensional Magneto-Optical Recording
Authors: Itoh Akiyoshi 
Published: April 2011

ABSTRACTIn this report, the newly developed three-dimensional magneto-optical (MO) recording scheme and the experimental results are reported. A part of this work has been done as the national project of 3D-MO (3-dimensional MO) project. It started at September 1998 and ended March 2002 as a part of the national project “Nanometer-Scale Optical High Density Disk Storage System” and aimed at achieving 100 Gb/in2 in storage density. Three-dimensional MO recording is one of the prosperous candidates of next generation ultra high density recording. Magnetic amplifying MO system (MAMMOS) is employed for achieving the novel three-dimensional MO recording. Double-MAMMOS scheme consists of 2-recording layers of differing compensation temperature (Tcomp ) and one readout layer was proposed and discussed.With write/read test it is succeeded to show the results corresponding to a 100 Gb/in2 (50 Gb/in2 × 2) recording density. We also proposed and showed results of simulations of a new type of Double-MAMMOS in which the recording layers can hold quadri-valued information by single writing process.
Temperature Dependence Free Magneto-Optical (Tb,Bi)Fe Garnet Films Grown By LPE Method
Authors: Imaizumi Nobuo , Fukuhara Takashi , Kuwano Yasuhiko , Shiroki Kenichi 
Published: April 2011

ABSTRACTBi-substituted TbFe Garnet films grown by Liquid-Phase Epitaxial (LPE) method are demonstrated as a candidate for the temperature dependence free Faraday rotator in the telecom devices or the optical sensors applications. Several types of substituted GdGaGarnet (SGGG) substrates are applied in the tests. At X=0.48 o 0.56 in the Tb(3-X)BiXFe5O12, a series of very low temperature dependence garnet films are fabricated on the lattice constant of 12.465Å (GdCa)3(GaZrMg)5O12 substrates through the LPE-grown processing with optimized flux compositions. A couple of device applications are also demonstrated using these suppressed temperature dependence garnet films.
Experiments Towards the Realisation of a Monolithically-Integrated Optical Isolator Incorporating Quasi-Phase Matched Magneto-Optical Effects
Authors: Holmes Barry. M. , Hutchings David. C. , Bregenzer Josef. J. 
Published: April 2011

ABSTRACTExperiments towards the realisation of the necessary components for future integrated waveguide optical isolators have been conducted. The design, fabrication and characterisation of GaAs/AlGaAs reciprocal mode converters, realised through the use of three novel approaches, is reported. These devices have been tested at λ=0.9m and 1.3m, producing TE-TM conversion efficiencies up to 70%. Initial investigations into the inclusion of magneto optic materials with III-V semiconductor structures for non-reciprocal mode conversion are also discussed.
Cd1-xMnxTe Magneto-Optical Waveguide for Monolithical Integration of Optical Isolator into Optoelectronics Circuits
Authors: Zayets Vadym 
Published: April 2011

ABSTRACTDiluted magnetic semiconductor Cd1-xMnxTe was proposed as a magneto-optic material for waveguide optical isolator. Waveguide propagation loss below 1 dB/cm, complete magneto-optical mode conversion and optical isolation of 20 dB were demonstrated with Cd1-xMnxTe waveguides grown on GaAs substrate. The high isolation ratio, high magneto-optic effect and low propagation loss achieved in the magneto-optical waveguide grown on the semiconductor substrate shows the feasibility of monolithical integration of an optical isolator with semiconductor optoelectronic devices.
Hybrid semiconductor-ferromagnetic-metal active optical isolator.
Authors: Zayets Vadym , Ando Koji 
Published: April 2011

ABSTRACTThe effect of non-reciprocal loss/gain in semiconductor-ferromagnetic-metal hybrid was studied. It is shown that the optical loss/gain of this semiconductor-ferromagnetic-metal hybrid differs for the forward and backward propagation when the magnetization is perpendicular to the light propagation and lies in the film plane. Using this effect a new design of optical isolator is proposed, which is beneficial for monolithic integration of optical isolator with laser diode. The non-reciprocal loss was experimentally observed in Ga1-xAlxAs waveguide covered by Co for the first time.
Fabrication of a TE Mode InGaAsP Active Waveguide Optical Isolator Based on the Nonreciprocal Loss shift
Authors: Shimizu Hiromasa , Nakano Yoshiaki 
Published: April 2011

ABSTRACTWe have fabricated a TE mode InGaAsP active waveguide optical isolator based on the nonreciprocal loss shift in an optical fiber telecommunication wavelength of 1550nm. We demonstrated a TE mode nonreciprocal loss shift of 9.3dB/mm under a magnetic field of +/-1kG in the facricated InGaAsP active waveguide with Fe on an InP substrate at a wavelength of 1560nm. This result opens a way to the monolithic integration of semiconductor-waveguide-type optical isolators with edge emitting semiconductor lasers.
Application of Magnetic Garnet Films for Magnetooptical Imaging of Magnetic Field Distributions
Authors: Dötsch H. , Holthaus C. , Trifonov A. , Klank M. , Hagedorn O. , Shamonin M. , Schützmann J. 
Published: April 2011

ABSTRACTRare-earth iron garnet films of high quality can be grown by liquid phase epitaxy on paramagnetic substrates of gadolinium galliumgarnet. Such films are currently used for imaging of the spatial distribution of magnetic fields. This application is based on the Faraday rotation which can strongly be enhanced by bismuth incorporation.The physical properties of the films can be controlled by the chemical composition, the growth conditions and the crystallographic orientation. The sensor properties like sensitivity, dynamic range, signal linearity and unambiguity must be optimized according to the application desired. These properties, however, are not independent of each other. In addition, they strongly depend on the optical wavelength. Thus, it is necessary to find compromises.The influence of Faraday rotation, Faraday ellipticity, optical absorption, magnetic anisotropies and film thickness on the performance of a magnetooptical indicator film is investigated. Based on the swing of the photoresponse, a new optimization process is introduced. The process is experimentally verified and application examples are demonstrated.Furthermore, two methods are presented to enhance the sensitivity of magnetooptical sensors. Using specific crystallographic orientations, an easy plane of magnetization can be induced which is inclined with respect to the film plane. If the magnetization lies in this plane a very high sensitivity is achieved. The dependence of the geometrical orientation of the easy plane on the growth direction is calculated and the sensitivity and dynamic range are derived. Experimental results of a [112] oriented garnet film are in good agreement with calculations.Garnet films which are magnetized along the film normal due to a strong induced uniaxial anisotropy support magnetic domains. If the collapse field perpendicular to the film plane is small, such films can be used as very sensitive indicator films. Such films are easier to prepare than sensitive in-plane films. However, the spatial resolution is limited by the size of the domains. This disadvantage can be avoided by applying a bias field in the film plane. Directly at the in-plane collapse field the sensor film is in-plane magnetized yielding high spatial resolution at still high sensitivity. The variation of magnetooptical images with in-plane induction is demonstrated. Experimental results are in agreement with calculations.
Growth and Characterization of Magnetooptic Garnet Films with Planar Uniaxial Anisotropy
Authors: Fratello Vincent J. , Mnushkina Irina , Licht Steven J. , Abbott Robert R. 
Published: April 2011

ABSTRACTThick film garnet Faraday rotators with perpendicular anisotropy have limited utility for variable polarization rotation applications because multi-domain effects result in large effective insertion losses in device applications. Thick film growth of (BiGdLu)3(FeGaAl)5O12 on (100) substrates yields growth-induced anisotropies ranging from positive anisotropy perpendicular domains to negative anisotropy in-plane domains. Planar domains show variable magnetization by domain rotation with a uniform projection of magnetization along the axis of light propagation. This can produce low-loss devices when operated in sub-saturation applications such as magnetic field sensors, variable optical attenuators and polarization controllers.
Clamped Ferroelectric and Magnetic Domain Walls and their Application to Memory Engineering
Authors: Hanamura Eiichi , Tanabe Yukito 
Published: April 2011

ABSTRACTA family of rare-earth metal manganites are antiferromagnetic (AFM) ferroelectrics and some of these may show also weak ferromagnetism. First we will show how to observe the ferroelectric (FEL) and AFM domain structures by the interference effects of second harmonic generation (SHG). Second, the observed clamping of the AFM domain wall (DW) to the FEL domain boundary (DB) is intuitively explained by the group theoretical consideration of the magnetic anisotropy energy depending upon the sign of the FEL polarization. Third, the application of these clamped DW-DB to the memory engineering will be briefly discussed.
Characterization of Li insertion mechanisms in negative electrode materials for Li-ion batteries by Mössbauer spectroscopy and first-principles calculations
Authors: Lippens P.E. , Aldon L. , Ionica C.M. , Robert F. , Olivier-Fourcade J. , Jumas J.C. 
Published: April 2011

ABSTRACTThe Mössbauer spectroscopy is an efficient experimental tool to study lithium insertion mechanisms in negative electrodes of Li-ion batteries at the atomic scale. However, a quantitative interpretation of the experimental data is often difficult due to the complexity of the spectra and we propose to use first-principle calculations of the hyperfine parameters. Three different types of negative electrode materials are considered. First, the experimental 119Sn Mössbauer spectrum obtained for the insertion of 3.5 Li into SnO is compared to the theoretical spectrum, which clearly establishes the existence of Li-Sn stable phases. Then, the analysis of the 121Sb Mössbauer spectra for metal antimonides at the end of the first discharge shows different behaviours depending on the lithium rate. Finally, tin and iron doped titanates are considered to study changes in Ti local environments during lithium insertion.
Reversible electrochemical extrusion of copper by lithium. Role of the initial structure
Authors: Morcrette M. , Leriche J.B. , Chevalier F. , Rozier P. , Dupont L. , Poizot P. , Laffont L. , Tarascon J.M. 
Published: April 2011

AbstractThe reversible Li-driven copper extrusion/insertion mechanism into Cu2.33V4O11 electrode has been studied and a new ion-exchanged assisted electrochemical process was unravelled. This process, entails during the charging of “Lix V4O11 + Cu0” composite electrodes vs. Li, the oxidation of Cu metal into copper ions that concomitantly exchanged for lithium ions to produce back Cu2.33V4O11. The electrochemical performances of such cells, namely in terms of capacity retention and power rates, are explained on the basis of the electrochemically generated Cu ions that can either being ion-exchanged with Li within the Li-V-O host or released in the solution. When the former does occur we show, owing to excellent kinetic of both, the ion-exchanged reaction between Cu2+ and Li+ together with a fast charge transfer between Cu0 and Cu2+, that high rate performances electrodes can be achieved whereas when the latter prevails the cells rapidly fail. It appears then that Cu+ ions should be removed. Thus, a new copper vanadate Cu1.1V4O11 phase has been isolated by both chemical and electrochemical removal of Cu from the mother Cu2.33V4O11 phase, and its electrochemical performance in Li cells studied. The removal of copper was shown to occur in a topotactic manner resulting in a stacking of [V4O11]n layers linked by differently coordinated copper ions. This new phase reversibly reacts with 5 Li, leading to a capacity of about 260 mAh/g, through a process involving a reversible displacement reaction entailing to the growth/disappearance of Cu dendrites.
Synthesis, Characterization and Properties of New Vanadia-Alumina and Vanadia-Silica Composites Prepared by Interpenetrating Polymer Network Approach
Authors: Zampronio Elaine C. , Barbosa Glauciane N. , Graeff Carlos F.O. , Lassali Tânia A.F. , Oliveira Herenilton P. 
Published: April 2011

ABSTRACTIn this study, we incorporated vanadium pentoxide xerogel into an alumina matrix and into a silica matrix in order to improve the structural stability by incorporating the electroactive material into an inert matrix which provides structural stability to the electrode. The novel materials were characterized by powder X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectrometry, cyclic voltammetry and impedance spectroscopy. V2O5/SiO2 and V2O5/Al2O3 xerogel composites prepared by soft chemistry present conductivity almost five orders of magnitude higher than other related systems. The electrochemical behavior is quite similar to that found for V2O5 xerogel. In addition, the cyclic voltammetric and electrochemical impedance spectroscopy studies demonstrated that the alumina and silica matrices provide an improvement of the electrochemical properties mainly in relation to the kinetics of the lithium electroinsertion into the oxide matrix with little decrease of total charge during successive redox cycles. Overall, the synthetic approach applied in this study is extremely attractive due to its simplicity and can provide new strategies for tailoring new materials and future family members for electrochromic devices, batteries and chemical sensing.
Co-Sintering of Dense Electrophoretically Deposited YSZ Films on Porous NiO-YSZ Substrates for SOFC Applications
Authors: Savo Giuseppe , Rainer Alberto , D'Epifanio Alessandra , Licoccia Silvia , Traversa Enrico 
Published: April 2011

ABSTRACTAn original process for the preparation of YSZ dense films with a thickness lower than 10 μm over NiO-YSZ substrates is presented. This process involves the preparation of a green membrane of NiO-YSZ and subsequent electrophoretic deposition (EPD) of commercial YSZ powder on this polymer-rich membrane. A single thermal treatment allowed removal of the organic compounds, sintering of the layers and full densification of the electrolyte.
A Titania Nanotube-Array Room-Temperature Sensor for Selective Detection of Low Hydrogen Concentrations
Authors: Varghese Oomman K. , Mor Gopal K. , Paulose Maggie , Grimes Craig A. 
Published: April 2011

ABSTRACTA tremendous variation in electrical resistance, from the semiconductor to metallic range, has been observed in titania nanotube arrays at room temperature, ≈25°C, in the presence of low ppm hydrogen gas concentrations (≤ 1000 ppm). The nanotube arrays are fabricated by anodizing titanium foil in an aqueous fluoride containing electrolyte solution. Subsequently, the arrays are annealed in an oxygen ambient, then coated with a 10 nm layer of palladium by evaporation. Electrical contacts are made by sputtering a small (e.g. 1 mm diameter) platinum disk atop the Pd coated nanotube-array. These sensors exhibit a resistance variation of the order of over 107 (1,000,000,000%) in the presence of 1000 ppm hydrogen at 23°C. To the best of our knowledge this dynamic change in electrical resistance the largest known response of any material, to any gas, at any temperature. The sensors demonstrate complete reversibility, repeatability, high selectivity, no drift and wide dynamic range. The nanoscale geometry of the nanotubes, in particular the points of tube-to-tube contact, is believed to be responsible for the outstanding hydrogen gas sensitivities.
Composite Inorganic Filler Based Electrolyte Membranes for Fuel Cells Applications
Authors: Aricò Antonino S. , Baglio Vincenzo , Blasi Alessandra Di , Antonucci Vincenzo 
Published: April 2011

ABSTRACTVarious recast Nafion® composite membranes containing ceramic oxide fillers with different surface characteristics (SiO2, SiO2-PWA, Al2O3, ZrO2) have been investigated for application in high temperature direct methanol fuel cells (DMFCs). Cell resistance at 145 °C increases as a function of the pH of slurry of the inorganic filler indicating a strong influence of the acid-base characteristics on the electrolyte conductivity. This effect has been attributed to the different water retention capabilities of the various membranes. Fuel cell performance at 145 °C, expressed as both maximum power density and current density at 0.5 V cell potential, increases almost linearly as the pH of slurry of the oxide materials decreases. Appropriate selection of the surface properties for the inorganic fillers allows to enhance the proton conductivity and extends the operating temperature range of composite membranes. An infrared spectroscopic investigation of inorganic fillers employed in composite membranes has been carried out. The surface acidity of the fillers appears to influence the bending and stretching vibrational frequencies of the water physically adsorbed on the filler surface. Inorganic fillers characterised by acidic properties undergo a strong interaction with water and enhance the DMFC performance at high temperature.
Influence of the grain boundaries on conductivity of yttrium stabilized zirconia
Authors: Petrovsky V. , Jasinski P. , Anderson H.U. , Petrovsky T. 
Published: April 2011

ABSTRACTThe influence of the grain boundaries on the ionic conductivity of yttrium stabilized zirconia (YSZ) was investigated. The initially nanocrystalline samples were prepared using a tape casting process. The samples were annealed at different temperatures in the range from 1000 to 1400°C to overlap the grain size from 100nm to ∼10μm and investigated using impedance spectroscopy. Two distinct semicircles were found on all YSZ samples corresponding to the influence of the grain and grain boundary on the resistance. The activation energies for both resistances are very close (1.00 and 1.03eV correspondingly). The grain resistance does not change significantly during the annealing process, but the grain boundary resistance decreases after high temperature annealing which causes a decrease in the overall resistance of the material. The calculations show that the decrease in the grain boundary resistance is connected only with the increase in the grain size and the specific grain boundary resistance (per unit surface area of grain boundary) does not change with annealing.
Preparation and characterization of lead ruthenate based composite cathodes for SOFC applications
Authors: Esposito Vincenzo , Traversa Enrico , Wachsman Eric D. 
Published: April 2011

ABSTRACTNanometric pyrochlore lead ruthenate (Pb2Ru2O6.5) powders were prepared using a new chemical route as a possible candidate for cathode materials in solid oxide fuel cells (SOFCs). Pb2Ru2O6.5 was mixed with yttria-stabilized zirconia (YSZ) and erbia-stabilized bismuth oxide (ESB) to fabricate porous composite electrodes. Pure pyrochlore or composite electrodes were deposited as thick films onto YSZ and ESB electrolytes. Powders and films were analyzed using X-ray diffraction (XRD) analysis and field emission scanning electron microscopy (FE-SEM). Electrochemical features of the electrodes were investigated using electrochemical impedance spectroscopy (EIS) measurements at different temperatures in air for symmetric cells. The composite electrodes were compared to single Pb2Ru2O6.5 phase electrodes to evaluate the effect on polarization of the addition of the pure ionic conductor phase in the electrodes.
Synthesis, spectroscopic and electrochemical characterization of hybrid membranes for Polymer Electrolyte Membrane Fuel Cells.
Authors: Vona Maria Luisa Di , Marani Debora , D'Epifanio Alessandra , Traversa Enrico , Trombetta Marcella , Licoccia Silvia , Caldarelli Stefano , Knauth Philippe 
Published: April 2011

ABSTRACTCommercial polyether-etherketone was sulfonated and reacted with SiCl4 to obtain a hybrid polymer. Polymers having different inorganic content were characterized by 29Si NMR, ATR/FTIR spectroscopies and mass spectrometry (FAB-MS) demonstrating the formation of covalent bonds between the organic and inorganic components and the absence of dispersed inorganic silicon. The physicochemical properties of the hybrids were suitable for the preparation of membranes which showed sufficiently high conductivity values to make them promising candidates for application in PEMFCs.
Progress in Producing Large Area Flexible Dye Sensitized Solar Cells
Authors: Mandal Krishna C. , Choi Michael , Noblitt Caleb , David Rauh R. 
Published: April 2011

ABSTRACTDye sensitized nanocrystalline TiO2 solar cells have been reported with over 11% efficiency and are extremely promising as very low cost and lightweight photovoltaic sources. However, most reports are for cells of low area fabricated on glass, which withstands processing temperatures of ∼450°C. In this paper, we describe the fabrication and performance of cells made on flexible ITO-coated polyethylene terephthalate (PET) substrates with 6” × 3” dimensions. To improve the efficiency in the cells, we enhanced the ITO current collection efficiency with metallization fingers. The fingers resulted in a >10 fold increase in short-circuit current under normal solar illumination compared to cells without metallization. Further improvements were realized by passivating the metallization fingers at the metal/polymer electrolyte interface.