bluuebunny/crossref_metadata_2025_split huggingface dataset:
Response of the Electric Field Gradient in Ion implanted BaTiO3 to an External Electric Field
Authors: Dietrich Marc , Bartels Jörn , Deicher Manfred , Freitag Kristian , Samokhvalov Vyacheslav , Unterricker Sepp 
Published: April 2011

AbstractSingle crystalline, ferroelectric BaTiO3 as material with the highest piezoelectric constants among the perovskites with ordered sublattices was implanted with 111In(111Cd). The electric field gradient at the Ti position was measured with perturbed γγ-angular correlation spectroscopy (PAC) while the crystal was exposed to an external electric field. A quadratic dependence could be observed: νQ(E) = (34.8(1) + 0.16(4) E/kV/mm + 0.080(2) E2/kV2/mm2) MHz. Point charge model calculations reproduce the linear change of Vzz, but not the quadratic term. The polarizability of the host ions of BaTiO3 is known to be nonlinear with respect to an electric field. The resulting quadratic shift of the electron density is reflected in the strength of the EFG.
Preparations and Characterizations of Epitaxial SrBi2Ta2O9 Thin Films
Authors: Saito Keisuke , Mitsuya Masatoshi , Suzuki Toshimasa , Nishi Yuji , Fujimoto Masayuki , Nukaga Masanori , Yamaji Isao , Akai Takao , Funakubo Hiroshi 
Published: April 2011

AbstractEpitaxial (001)-, (116)- and pseudo (103)-oriented Sr0.35Bi2.2Ta2O9 (SBT (0.35/2.2/2.0)) films were successfully grown on (001), (110) and (111) SrTiO3 substrates, respectively. High-resolution X-ray diffraction reciprocal space mapping (HRXRD-RSM) measurements and pole figure measurements clearly indicated that the (116)-oriented SBT (0.35/2.2/2.0) film consisted of two growth domains those c-axis are separated 180° apart in in-plane and pseudo (103)-oriented SBT film consisted of three growth domains those c-axis are separated 120° apart in in-plane. Moreover, lattice parameter measurements indicated that SBT films grew in fully relaxed state.
Use of an External Electric Field to Convert the Paraelectric Phase to the Ferroelectric Phase in Ultra-thin Copolymer Films of P(VDF-TrFE)
Authors: Poulsen Matt , Adenwalla S. , Ducharme Stephen , Fridkin V.M. , Palto S.P. , Petukhova N.N. , Yudin S.G. 
Published: April 2011

AbstractX-ray diffraction was used to probe the structural changes associated with the conversion of the paraelectric phase to the ferroelectric phase that results from the application of a large external electric field. The samples under study are ultrathin (150 to 250 Å) Langmuir-Blodgett films of the copolymer vinylidene fluoride (70%) with trifluoroethylene (30%) deposited on aluminum-coated silicon. Theta-2theta X-ray diffraction was used to measure the change in inter-layer spacing perpendicular to the film surface. Upon heating at zero external electric field, the crystalline films undergo a structural phase transition, at 100± 5°C, from the all-trans ferroelectric phase to the trans-gauche paraelectric phase. [1,2] Above the phase transition temperature, the non-polar paraelectric phase can be converted back to the polar ferroelectric phase, in a smooth continuous process, using a large external electric field (∼1 GV/m). For example, at 100° C the ferroelectric phase first appears above 0.2 GV/m and increases steadily in proportion while the paraelectric phase decreases until complete conversion to the ferroelectric phase is achieved at approximately 0.6 GV/m.
The Physics of Electric Field Effect Thermoelectric Devices
Authors: Sandomirsky V. , Butenko A. V. , Levin R. , Schlesinger Y. 
Published: April 2011

AbstractWe describe here a novel approach to the subject of thermoelectric devices. The current best thermoelectrics are based on heavily doped semiconductors or semimetal alloys. We show that utilization of electric field effect or ferroelectric field effect, not only provides a new route to this problem, bypassing the drawbacks of conventional doping, but also offers significantly improved thermoelectric characteristics. We present here model calculation of the thermoelectric figure of merit in thin films of Bi and PbTe, and also discuss several realistic device designs.
Crystalline and Electrical Properties of Ferroelectric Silver Niobate-tantalate thin Films
Authors: Koh Jung-Hyuk , Khartsev S.I. , Grishin Alex , Petrovsky Vladimir 
Published: April 2011

AbstractFor the first time AgTa0.38Nb0.62O3 (ATN) films have been grown on the La0.7Sr0.3CoO3 (LSCO)/LaAlO3 single crystal as well as onto Pt80Ir20 (PtIr) polycrystalline substrate. Comprehensive X-ray diffraction analyses reveal epitaxial quality of ATN and LSCO films on the LaAlO3(001) substrate, while ATN/PtIr films have been found to be (001) preferentially oriented. Dielectric spectroscopy performed for ATN films and bulk ceramics in a wide temperature range 77 to 420 K shows the structural monoclinic M1-to-monoclinic M2 phase transition occurs in films at the temperature 60 °C lower than in ceramics. The tracing of the ferroelectric hysteresis P-E loops indicates the ferroelectric state in ATN films at temperatures below 125 K and yields remnant polarization of 0.4 μC/cm2 @ 77 K. Weak frequency dispersion, high temperature stability of dielectric properties as well as low processing temperature of 550 °C make ATN films to be attractive for various applications.
Thin Film Superlattices of Lead Based Relaxors
Authors: Corbett M. H. , Gregg J. M. , Bowman R. M. 
Published: April 2011

AbstractThin film capacitor structures in which the dielectric is composed of superlattices of the relaxors [0.2Pb(Zn1/3Nb2/3)O3 – 0.8BaTiO3] and Pb(Mg1/3Nb2/3)O3 have been fabricated on MgO {100} substrates by Pulsed Laser Deposition. Structural studies show dielectrics to be 100% perovskite, with strong chemical distinction between individual relaxor layers. The dielectric properties of the superlattices were investigated as a function of periodicity. Significant enhancement of the dielectric constant was observed in relatively fine-scale superlattices, consistent with previous studies. However, unlike previous work, in these relaxor superlattices dielectric enhancement is not associated with increased loss. Rather tan δ is low across the entire superlattice series. Polarisation measurements as a function of temperature suggest that the observed enhancement in dielectric constant is associated with the onset of coupled behaviour. The thickness of the individual layers in the superlattice at which coupled functional behaviour becomes apparent is ∼10nm and is comparable to that found in literature for coupled structural behaviour.
Etching Characteristics of Noble Metal Electrode
Authors: Schneider St. , Kohlstedt H. , Waser R. 
Published: April 2011

AbstractThe objective of this work was to develop a process to pattern noble metal electrodes. To systematically investigate possible reactive etch process regions, characterized by volatile etch products, we used a reactive ion beam etching (RIBE) tool with a filament free ICP source. This configuration gives us exact control over the beam energy and the current density, and allows to use reactive gases. An energy dispersive quadrupole mass spectrometer is fitted to the chamber for in situ monitoring.We study the influence of the beam energy and the beam current impinging on the wafer surface as well as it's angular dependence. Several additives to the chlorinated process chemistry are investigated and characterized in terms of their role to help to increase the etch rate, maintain a vertical profile, or to enhance process selectivity.The main focus of the study is on Platinum. Blanket films were used to describe the influence of the material, and analysis were carried out to characterize the process in terms of etch rate, residues and selectivity.
New Pt/(Bi,La)4Ti3O12/Si3N4/Si MFIS Structure for FET-Type Ferroelectric Memories by the Sol-Gel Method
Authors: Kijima Takeshi , Fujisaki Yoshihisa , Ishiwara Hiroshi 
Published: April 2011

AbstractThe well c-axis-oriented Bi3.25La0.75Ti3O12 films with good crystallinity and good surface morphology were obtained at temperatures higher than 600°C It was also found in a Pt / 100nm-Bi3.25La0.75Ti3O12 / 3nm-Si3N4 / Si ( metal / ferroelectric / insulator / semiconductor ) structure that C-V characteristics showed a hysteresis loop with a memory window of about 1V and both the high and low capacitance values kept at zero bias voltage did not change for more than 3 hours.
Preparation and Characterization of Ba and Nb Substituted SrBi2Ta2O9 Compounds
Authors: Das Rasmi R. , Dobal P. S. , Dixit A. , Perez W. , Tomar M.S. , Melgarejo R. E. , Katiyar Ram S. 
Published: April 2011

AbstractBi-layered ferroelectric compounds are considered most promising for non-volatile memory applications due to their high fatigue endurance. We have prepared SrBi2Ta2O9 powders with Ba (A sites) and Nb (B sites) substitutions using a novel solution based route. The powders were pressed and sintered at 1050°C to obtain high quality targets. Thin films were prepared using these ceramic targets on Pt/TiO2/SiO2/Si substrates using pulsed laser deposition (PLD) technique. The effects of growth conditions on phase formation as well as structural and electrical properties in films are studied. Initial results on films show good hysteretic characteristics. Though phase formation begins at much lower temperature, these films crystallize in a complete layered perovskite phase when prepared at 700°C. Optical phonon modes in these materials exhibit systematic variations with changing compositions. The changes in the Raman spectra are explained in terms of Ba and Nb substitutions at A and B sites, respectively. The temperature dependence of Raman spectra exhibits the substitution induced changes in the transition temperatures of these materials.
Improved Deposition Process of CVD-(Ba,Sr)TiO3 on Ru
Authors: Tarutani M. , Sato T. , Yamamuka M. , Kawahara T. , Horikawa T. , Takenaga T. , Yoneda Y. , Kuroiwa T. , Matsuno S. , Shibano T. 
Published: April 2011

Abstract(Ba,Sr)TiO3 [BST] films were deposited by the flash vaporization CVD method with a unique liquid delivery system. An inductively coupled plasma mass spectrometry [ICP-MS] analysis revealed the decline of (Ba+Sr)/Ti molar ratio of the initial BST-layer on Ru. By readjusting the flow ratio of liquid sources and using a two-step deposition method, we obtained 30-nm-thick BST films with uniform composition profile, exhibiting good electrical properties. The leakage property, however, was severely deteriorated in BST films less than 24 nm thick. A SEM observation showed the presence of micro-roughness or micro-hillocks in these films, which were confirmed to be caused by Ru oxidation. Therefore, an annealing process of the Ru electrode was added for its planarization, and the CVD process was also improved. As a result, we obtained smooth and finely crystallized ∼ 20-nm-thick BST films with good electrical properties of equivalent SiO2 thickness (teq) ∼ 0.45 nm and leakage current < 1 × 10−7 A/cm2. We also measured properties of BST films deposited on the 3-D Ru electrode. The results are briefly discussed.
Transient Behavior of the Polarization in Ferroelectric Thin Film Capacitors
Authors: Lohse Oliver , Grossmann Michael , Bolten Dierk , Boettger Ulrich , Waser Rainer 
Published: April 2011

AbstractThe understanding of the polarization switching process of ferroelectric capacitors is highly relevant for the development and optimization of FeRAM devices. We report on the characterization of Pb(Zr,Ti)O3 thin films which have been studied by means of dedicated rectangle pulse measurements. Decreasing the voltage level of the excitation pulses decelerates the polarization switching significantly to the range of milliseconds and reduces the switchable polarization. In this work the influence of niobium (Nb) doping on the switching properties of PZT thin films prepared by CSD are investigated to reach the aspired conditions of low voltage operation, read and write access pulses in the range of nanoseconds. For the implementation of the transient behavior of ferroelectric capacitors in circuit design and simulation tools it is necessary to develop a model which precisely describes the polarization hysteresis, the pulse switching behavior as well as the small signal capacitance. The fundamental considerations for this model are presented, based on an ideal ferroelectric capacitor, taking into account the Curie-von Schweidler behavior. The latter is observed in non-ferroelectric high-K materials as well as in ferroelectric thin films.
Deformation Mechanisms of a Micro-Sized Austenitic Stainless Steel with Fine Grains
Authors: Zhang G. P. , Takashima K. , Shimojo M. , Higo Y. 
Published: April 2011

ABSTRACTIn this study, deformation behavior of fine-grained austenitic stainless steel micro-cantilever beams was investigated using a newly developed testing machine for micro-sized specimens. The microbeams were deformed to different strain hardening stages of the material, and then the detailed deformation behavior on the specimen surface at the corresponding strain hardening stage was examined by scanning electron microscopy. Two deformation mechanisms corresponding to different strain hardening stages were found in the micro-sized austenitic stainless steel with fine grains. The dislocation slip mechanism characterized by the extensive dislocation slips and their interaction with grain boundaries resulted in the stage I strain hardening. With increasing deformation, the grain boundary sliding (GBS) mechanism at the stage II and subsequently intergranular cracking occurred. The differences in stress condition and work-hardening behavior on the top tension-side and rear compression-side surfaces of the micro-cantilever beam resulted in the different deformation behavior.
Corrosion Fatigue Tests of Micro-Sized Specimens
Authors: Mizutani Y. , Higo Y. , Ichikawa Y. , Morita A. , Takashima K. , Swain M.V. 
Published: April 2011

ABSTRACTCorrosion fatigue properties of micro-sized materials are extremely important to design MEMS devices and micro-machines used in corrosive environments. However, there have been few studies that investigate corrosion fatigue properties of micro-sized materials. Thus, it is necessary to develop a corrosion fatigue test method for micro-sized materials. However, there are several difficulties in corrosion fatigue tests on micro-sized specimens. It is also necessary to clarify the problems for the method and to find their solutions. In this investigation, a corrosion fatigue test method for micro-sized specimens has been developed and corrosion fatigue tests for micro-sized Ni-P amorphous alloy specimens have been carried out in a 0.9% NaCl solution. Specimens of cantilever-beam-type with dimensions of 10 × 12 × 50 μm3 were prepared from a Ni-P amorphous thin film by focused ion beam machining. Corrosion fatigue tests on the micro-sized specimens were succeeded, and environmental effects on fatigue properties of micro-sized specimens were clearly observed. Several problems and solutions for the method were described.
Curvature Model for an Ion-Machined Free-Standing Thin Film MEMS Device
Authors: Johnson H.T. , Bierden P. , Bifano T. G. 
Published: April 2011

ABSTRACTThe connection between processing effects and curvature of a free-standing poly-Si thin film MEMS structure is analyzed theoretically and compared to experimental data. Estimates are made for the strain resulting from processing and post-processing effects including Phosphorus implantation and chemically neutral ion-beam machining. The inferred strain distribution is used to predict the curvature of the free-standing structure upon release from its host substrate. Curvature predictions agree closely with experimental measurements for particular choices of the processing strain magnitudes. The analysis procedure is proposed as a means to determine the through-thickness stress distribution in a free-standing structure. The ion-beam machining procedure is found to be a useful method for planarizing free-standing thin film structures with undesirable curvature due to process-induced stress.
Asymmetrical Polysilicon Electrothermal Microactuators for Achieving Large In-Plane Mechanical Forces and Deflections
Authors: Kolesar Edward S. , Allen Peter B. , Boydston Noah C. , Howard Jeffery T. , Ko Simon Y. , Ruff Matthew D. , Wilken Josh M. , Wilks Richard J. 
Published: April 2011

ABSTRACTThis research focuses on the design and experimental characterization of two types of asym- metrical MEMS electrothermal microactuators. Both MEMS polysilicon electrothermal microac- tuator designs use resistive (Joule) heating to generate thermal expansion and movement. Deflection and force measurements as a function of applied electrical power are presented.
Phenomenological Model of Non-Evaporated Getter for Micro-electromechanical Systems (MEMS) Applications
Authors: Kondoleon Caroline A. , Marinis Thomas F. 
Published: April 2011

ABSTRACTThere has been increasing interest in the development and use of micro-electromechanical systems (MEMS) for various applications. Some MEM devices such as gyroscopes, accelerometers and bolometers, must be sealed under vacuum, at pressures below 10 millitorr, for efficient operation. A gas absorbing material (getter) is placed in the packages of these devices, to help maintain vacuum levels over service lives of many years. Heating under vacuum, just prior to sealing the package, activates getter, of this type. This study was undertaken to develop a model that could be used to estimate the quantity of getter needed as well as optimize the activation process subject to process constraints on time and temperature.The material studied was a titanium and zirconium-based alloy (7:3 by weight) non-evaporable getter in the form of strips produced by SAES Getters. The zirconium alloy consisted of zirconium (70.0%), vanadium (24.6%) and iron (5.4%) by weight. The getter was analyzed under different ambient conditions of temperature, time and atmospheric pressure. Auger electron spectroscopy (AES) depth profiling was used to analyze the diffusion depth of the contaminant gases absorbed by the getter material under each condition. The data acquired from the depth profiles were fit to a simple diffusion model. This model is currently being validated, by activating the getter material under various ambient conditions, and measuring pressures and gas compositions inside packages using a residual gas analyzer (RGA). The utility of this model for optimization of getter activation and estimating package vacuum levels over time will be discussed.
R&D of Coated Conductors in Japan
Authors: Shiohara Yuh , Izumi Toru 
Published: April 2011

ABSTRACTThe recent achievements of critical current densities in excess of 1MA/cm2 at 77K in YBCO films deposited over appropriate bi-axially textured buffer layers/metal substrates have stimulated interest in the potential future applications of coated conductors at liquid nitrogen temperature and high magnetic fields, which are called as the next/second generation tape conductors. Several different processes for obtaining the bi-axially textured buffer layers/metal substrates as well as thicker film deposition processes and non-vacuum processes are reviewed. This paper reviews the research goals of the project including the recent development of the related research by individual research group in Japan.
Trapped Magnetic Field of a Mini - Bulkmagnet using YBaCuO Superconductors
Authors: Fujimoto Hiroyuki , Kamijo Hiroki 
Published: April 2011

ABSTRACTWe fabricated a mini-superconducting bulk magnet of 200 mm × 100 mm, consisting of 18 square bulks, 33 mm on a side and 10 mm in thickness, and magnetized the mini-magnet by field cooling. The mini-magnet showed the trapped magnetic field of larger than 0.1 T on the surface of the outer vessel of the magnet. The present preliminary study discusses the possibility of superconducting bulk magnets for the Maglev system, and trapped magnetic field properties of the mini-bulkmagnet using YBaCuO superconductors at 77K.
Fabrication of Large Melt-textured RE-Ba-Cu-O (RE = Gd, Dy) Superconductors and Their Trapped Magnetic Fields
Authors: Nariki Shinya , Sakai Naomichi , Murakami Masato 
Published: April 2011

ABSTRACTWe have succeeded in synthesizing RE-Ba-Cu-O (RE = Gd and Dy) bulk superconductors with excellent field trapping properties. Large c-axis oriented single-domain Gd-Ba-Cu-O bulk samples with Ag addition were melt-textured under controlled oxygen partial pressure of 1.0%. The Gd-Ba-Cu-O sample 50 mm in diameter could trap a high flux density of 2.4 T at 77 K. In addition, we measured the trapped field between two Gd-bulks in order to minimize the demagnetizing effect and found that it reached 3.3 T. The single-domain Dy-Ba-Cu-O/Ag bulk 48 mm in diameter was also fabricated in air and its trapped field was 1.9 T at 77 K.
High Pressure Synthesis of RuSr2MeCu2O8 (Me = Ho or Y)
Authors: Ruiz-Bustos R. , Gallardo-Amores J. M. , Morán E. , Attfield J. P. , Sáez-Puche R. , Alario-Franco M. A. 
Published: April 2011

ABSTRACTThe synthesis at high pressures ( ∼60 Kbar) and high temperatures (∼1100 °C) of the title new ruthenates has been achieved and the materials compared to the gadolinium analogue. The structure remains tetragonal (S.G. P4/mmm) and the cell parameters linearly decrease following the lanthanide contraction. Preliminary results concerning the complex magnetic properties of these materials, where superconductivity, antiferromagnetism and a superimposed ferromagnetic ordering coexist, are presented.
La2-xSrxCuO4-σ ceramics: synthesis, oxygen mobility and perspectives of catalytic applications
Authors: Mazo Galina N. , Shlyakhtin Oleg A. , Savvin Stanislav N. 
Published: April 2011

ABSTRACTTwo special processing procedures based on freeze-drying synthesis have been developed in order to obtain fine (100nm) single phase LaSrCuO4−σ powders and dense ceramics. The rate of phase formation is strongly influenced by the composition of the salt precursor while the most crucial factors are heating rate and PO2 during decomposition. Studies of oxygen mobility in La2−xSrxCuO4−σ performed by dynamic-thermal O18-isotope exchange method revealed that all ceramic samples possess substantial catalytic activity in the isotope exchange reaction between oxygen molecules 32O2 and 36O2. Besides, substitution of La for Sr in La2−xSrxCuO4−σ (x =1) results in the decrease of oxygen release onset temperature from 460 to 380°C. Such a dependence correlates quite well with data on diffusion coefficients calculated for various x from the results of coulometric titration experiments. Samples with x=1 demonstrated also good catalytic activity in the reaction of CO oxidation.
Proton Beam Texturing of Superconducting YBaCuO Ceramics
Authors: Kalanov Makhmud , Ibragimova Elvira M. 
Published: April 2011

ABSTRACTResistive superconducting (SC) transition, current-voltage characteristics, and X-ray diffraction (XRD) of YBaCuO ceramics have been studied after exposure to 18 MeV proton beam at 300 K. In the interval of 1013 −5×1014 cm−2 the irradiation induced oxygenation of weak intergrain contacts and grain alignment, anisotropy and broadening of SC-transition measured along and across the proton beam, and residual magnetization were found. The proton induced anisotropic texture is responsible for the critical current increase at 77 K and the resistivity decrease at 90–200 K. In a higher dose interval of 1013 −1015 cm−2 the SC-transition parameters degrade and the resistivity increases, depending on a texture degree, weak intergrain links become deoxygenated and no texture occurs. The magnetization (pinning) and the anisotropy of SC-transition can be due to localization of charges at the proton induced defects (mostly in oxygen sublattices).