bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of Oxygen Vacancies on the Ferroelectric Properties of Pzt Thin Films
Authors: Kwok Chi Kong , Desu Seshu B. 
Published: March 2011

AbstractThe properties of ferroelectric thin films can be significantly influenced by the presence of point defects. The concentration of vacancies presented in these thin films is known to be one of the key parameters causing the degradation of these films when these films are subjected to polarization reversals.To study the effects of the vacancy concentration on the ferroelectric properties, sol gel PZT films and powders were annealed in different oxygen partial pressures. For the PZT films, the reduction of oxides to pure metals was not observed even with films annealed at 2×10−5 atmosphere of oxygen partial pressure. Samples annealed at low oxygen partial pressure (for instance, 10−3 and 2×10−5 atmosphere), which has more Pb and O2 depletions and consequently has more Pb and O2 vacancies, cannot be switched easily. The ratios of coercive field after and before fatigue increase as the defect concentrations of the annealed samples increase.
Crystallographic Aspects of Ferroelectric Pzt Thin Films Prepared by Laser Deposition Technique
Authors: Wong-Ng Winnie , Huang Ting C. , Cook Lawrence P. , Schenck Peter K. , Vaudin M.D. , Chiang Chwan K. , Brody P.S. 
Published: March 2011

AbstractX-ray diffraction techniques were used to study the crystallography of PZT thin films prepared by the laser deposition technique. This investigation included identification of phases formed during the annealing process and also the analysis of the profiles of selected diffraction peaks. The PZT films annealed below 800°C typically showed powder x-ray diffraction patterns corresponding to a cubic structure (i.e no peak splitting) instead of the tetragonal patterns characteristic of the target materials. The upper bound contribution of the macro and micro strain to the observed X-ray peak profile and positions was estimated. It was believed that the combined effect of small crystallite size together with residual strain, and possible local inhomogeneity gave rise to the broadening and displacement of the x-ray peaks, which subsequently masked off the splittings. At this stage the physical effect of high temperature annealing is not known. It is possible that as the annealing temperature increased, grain growth took place along with relaxation of residual strain, allowing peak splitting to be observed.
Undoped and Doped Perovskite Films: Sol-Gel Processing and Characterization
Authors: Klee Mareike , Waser Rainer 
Published: March 2011

AbstractThin undoped Pb(ZrxTi1−x)O3 (x=0.2-0.75), BaTiO3, SrTiO3 as well as acceptor (Mn, Ni) and donor (La, Ce) doped films with thicknesses of 0.2-1 μm have been deposited by a modified sol-gel process. The crystal structure and the morphology of the films as a function of the processing and composition were analyzed. The films were characterized with respect to their ferroelectric and dielectric properities e.g. permittivity, remanent polarization, coervice field strength, insulation resistance.
Lead Zirconate Titanate Stannate Thin Films for Large Strain Microactuator Applications
Authors: Brooks Keith G. , Chen Jiayu , Udayakumar K.R. , Cross L. Eric 
Published: March 2011

AbstractThin films of antiferroelectric tetragonal (Pb.97 La.02 )(Zr1-x-yTixSny)O3 have been synthesized from acetate and alkoxide precursors via a sol-gel process. A multiple layer spin coating procedure was used to prepare 0.4 gtm films on platinized silicon wafers. Crystallization of the films as confirmed by x-ray diffraction was achieved by rapid thermal annealing at 700°C for 20 seconds. Antiferroelectric to ferroelectric phase switching threshold fields were determined from P-E hysteresis curves. Longitudinal strain is reported as a function of applied electric field, with a maximum strain of 1.6×10-3 measured at an applied dc bias field of 120 kV/cm on a film of composition Pb.97 La.02 (Zr.60Ti.l0Sn.30 )O3. These films show promise for micromechanical actuator applications due to the high strain associated with field forced antiferroelectric to ferroelectric phase switching.
Chemical Vapor Deposition of Strontium-Barium-Niobate
Authors: Greenwald A. , Horenstein M. , Ruane M. , Clouser W. , Foresi J. 
Published: March 2011

AbstractSpire Corporation has deposited strontium-barium-niobate by chemical vapor deposition at atmospheric pressure using Ba(TMHD), Sr(TMHD), and Nb ethoxide. Deposition temperature as 550°C in an isothermal furnace. Films were deposited upon silicon (precoated with silica), platinum, sapphire, and quartz. Materials were characterized by RBS, X-ray diffraction, EDS, electron, and optical microscopy. Electrical and optical properties were measured at Boston University.
Cross-Sectional Tem Studies of Barium Strontium Titanate Deposited on Silicon by Pulsed Laser Ablation
Authors: Pinizzotto Russell F. , Jacobs Elizabeth G. , Yang Hong , Summerfelt Scott R. , Gnade Bruce E. 
Published: March 2011

AbstractBarium strontium titanate films were deposited onto silicon substrates using pulsed laser ablation deposition. The films were characterized using conventional and high resolution cross-sectional TEM. It was found that the grains were columnar with an average width of approximately 23 nm. An amorphous interfacial layer formed between the Si and BST in all cases. The interfacial layer thickness increased as the sample exposure to O2 increased. TiSi2 was also observed in all the films, although its location at the interface was not directly verified. There are no systematic effects of O2 overpressure on either the film thickness or film microstructure. However, the film which was fabricated with the greatest exposure to O2 may contain TixOy, and contains more equiaxed grains than the other samples. An interfacial layer was also observed at the Au-Pd/BST interface in a metal/ferroelectric/silicon capacitor. The significance of the results is the observation that BST may never come in direct contact with either capacitor electrode, which may explain why the fatigue behavior and electrical characteristics of ferroelectric capacitors depend so strongly on the interfaces.
Oxide Ferroelectric /Cuprate Superconductor Heterostructures: Growth and Properties
Authors: Ramesh R. , Chan W.K. , Gilchrist H. , Wilkens B. , Sands T. , Tarascon J.M. , Keramidas V.G. , Evans J.T. , Gealy F. Dan , Fork D.K. 
Published: March 2011

AbstractFerroelectric PbZr0.2Ti0.8O3/YBa2Cu3O7 heterostructures have been grown on single crystal LaAIO3 and on buffered [100] Si. The cuprate superconductors are used as metal-like bottom electrodes for the subsequent growth of the ferroelectric PZT thin film. Structural studies using x-ray diffraction, and transmission electron microscopy show that the PZT layer is free of large angle grain boundaries (i.e., single crystal-like). Rutherford backscattering studies reveal the composition of the PZT layer to be close to that of the target. Ferroelectric hysteresis measurements using both pulsed measurements and a variable frequency Sawyer-Tower circuit yield remnant polarization values (at 5V) in the range of 15-45μC/cm2 (depending on deposition conditions) with a coercive field in the range of 80-120kV/cm. At a cycling voltage of 5V, these heterostructures exhibit a fatigue lifetime of better than 2x1010 at 40kHz (the polarization decays by only 20% of the initial value). Pulsed poling experiments before and after show that the loss of polarization is reversible. These heterostructures also show excellent aging and logic state retention characteristics.
Piezoelectric Thin Film Ultrasonic Micromotors
Authors: Udayakumar K. R. , Chen J. , Brooks K. G. , Cross L. E. , Flynn A. M. , Ehrlich D. J. 
Published: March 2011

AbstractThin films of lead zirconate titanate have been fabricated for application to a new family of flexure-wave piezoelectric micromotors that are characterized by low speed and high torque. The high relative dielectric constant and breakdown strength of the films lead to high stored energy densities. Evaluation of the film as a bimorph yielded a value of -88 pC/N for the transverse piezoelectric strain coefficient, d31; the relevant electromechanical coupling factor, k31, calculated thereupon was 0.22. The development of the piezoelectric ultrasonic micromotors from the PZT thin films, and the architecture of the stator structure are described. Nonoptimized prototype micromotors show rotational velocities of 100-300 rpm at drives of 3-5 V.
Post-Processing of Pulsed Laser-Deposited Pzt Thin Films
Authors: Chiang C. K. , Wong-Ng W. , Cook L. P. , Schenck P. K. , Lee H. M. , Brody P. S. , Bennett K. W. , Rod B. J. 
Published: March 2011

AbstractPZT thin films were prepared by pulsed laser deposition on unheated Ptcoated Si substrates. As deposited, the films were amorphous. Films crystallized at 550 - 600 °C to produce predominantly crystalline ferroelectric PZT. Crystallization of the amorphous material was accompanied by a linear shrinkage of ∼2 %, as manifested in development of cracks in the film. Spacing, width and morphology of larger cracks followed a regular progression with decreasing film thickness. For film thicknesses less than 500 runm, much of the shrinkage was taken up by small, closely-spaced cracks of local extent. Implications for measurement of PZT thin film ferroelectric properties and processing are discussed.
Dynamics of Laser Ablation and Vaporization of PbZr0.54Ti0.66O3: Laser Fluence and Ambient Gas Effects
Authors: Leuchtner R.E. , Horwitz J.S. , Chrisey D.B. 
Published: March 2011

AbstractA systematic study of the gas phase products observed from the pulsed laser vaporization of a PbZro.54Ti0.46O3target was performed as a function of laser fluence and ambient gas pressure. At low fluences, ≤0.3 J/cm2, only Pb and PbO were observed, while at higher fluences, between 0.3 - 1.3 J/cm2, neutral atomic species Pb, Zr, and Ti were detected. Small oxide molecules and atomicions were also observed. These regimes are associated with two ejection mechanisms: thermal evaporation and ablation, respectively. No direct evidence of chemical reactions was found over the gas pressure range explored (0-5 mTorr). Within the 25 cm reaction cell distance however, the addition of both inert and reactive gases greatly changed the velocity distributions of the ejected species. The decrease in velocity (energy) as a function of gas pressure was due to physical scattering and could be modeled as a pseudo-first order bimolecular collision process. The scattering rate increased linearly with the physical cross-section of the background gas and was independent of the kinetic energy of the ablated species.
Microstructural Characterization of Epitaxial Bottom Electrodes, Buffered Layers, and Ferroelectric thin Films
Authors: Rou Shang Hsien , Graettinger T. M. , Chow A. F. , Soble C. N. , Lichtenwalner D. J. , Auciello O. , Kingon A. I. 
Published: March 2011

AbstractThree subjects are covered in this paper. First, a set of criteria are established to explain how epitaxial growth can be achieved for sol-gel processed ferroelectric thin films. These criteria describe the conversion of amorphous films to epitaxial films. Second, we report the microstructures of ion beam sputtered buffer layers, (100) MgO on (100) Si, and epitaxial bottom electrodes, (100) Pt on (100) MgO and (111) Pt on (0001) A12O3, for the integration of ferroelectric films with various types of substrates. Third, microstructures of the multilayered epitaxial films, (001) YBa2Cu307-δ on (100) KNbO3/(100) MgO and (100) KNbO3 on (100) MgO/(100) Si, are characterized. The results indicate that high quality epitaxial multilayered films can be obtained under the proper processing conditions.
Ferroelectricity of Lanthanum-Modified Lead-Titanate Thin Films Deposited on Nickel Alloy Electrodes
Authors: Ogawa Toshio , Shindou Satoshi , Senda Atsuo , Kasanami Tohru 
Published: March 2011

AbstractLanthanum-modified lead-titanate (Pbo.85Lao.1Ti03) thin films were fabricated by rf magnetron sputtering on various kinds of substrates such as single-crystal MgO (100), r-plane sapphire and SI (100) with an MgO thin film layer. All the films were able to be evaluated using nickel alloy electrodes which possess low reactivity with PbO, excellent heat-resistance and oxidation-resistance. The quality of these films was affected by the kind of substrate and crystal orientation of nickel alloy electrode used. Furthermore, by controlling the crystal orientation of the alloy electrode, films on Si (100) with an MgO (100) layer showed good ferroelectricity.
Yb3+ Sensitised Er3+ Doped Silica Optical Fibre with Ultra High Transfer Efficiency and Gain
Authors: Townsend J. E. , Barnes W. L. , Crubb S. G. 
Published: March 2011

ABSTRACTEfficient 1.54 μm emission under 1064nm excitation of Er3+/Yb3+ codoped silica fibre is reported. The energy transfer efficiency from Yb3+ to Er3+, of at least 85%, even under high inversion, is comparable to that in multicomponent glass fibres. Fibre design parameters are discussed and results presented. Small signal gain of ˜ 45dB is also measured and a power amplifier giving 145mW output power demonstrated.
Optical Properties of Materials for Optical Amplifiers at 1.3 μM
Authors: Hessen B. , Sunshine S. A. , Schneemeyer L. F. , Neeves A. E. , Reed W. A. 
Published: March 2011

ABSTRACTWe describe the preparation and near Infra-Red fluorescence characteristics of a series of transition metal (V2+, Ni2+, Cr4+) doped crystalline inorganic materials. Within isostructural series, the effect of changes in the host lattice on the transition metal fluorescence has been investigated. This allows selection and fluorescence tuning of transition metal ion/crystalline host combinations of possible use for optical amplification in the 1.31 μm telecommunication window
Site-Selective Specirdsmpy of Thulium-Doped Glasses
Authors: Pearson A. , Lincoln J. R. , Brocklesby W. S. , Carte J. N. 
Published: March 2011

ABSTRACTLaser operation has been demonstrated in Tm3+-doped optical fibres at several useful wavelengths, including 2.3μm, 2μm, 1.47μm and 800nm, and visible upconversion fluorescence observed in silica and ZBIAN hosts. The ground-state Stark structure is ∼600cm−1 wide, resulting in broad tuning ranges for the lasers studied so far. As several of these laser are operated quasifour level using the ground state multiplet, the structure of this multiplet influences the laser transitions significantly. We Ipresent site-selective line-narrowed fluorescence studies of thulium in ZBLAN1 and silica-based hosts at low temperatures, which show detail of Stark levels not present in the room-temperature luminescence spectrum. Comparison of these data for Tmi: ZBLAN with the performance of fibre lasers and amplifiers based on the 800nm transition explains aspects of the laser performance such as tuning range, and optimum pump wavelength for amplifiers. In addition these data give information about the site-to-site disorder within the inhcmogeneous line.
Optical properties of silica glasses having O2 and Cl2 molecules
Authors: Awazu Koichi , Kawazoe Hiroshi , Muta Ken-ichi 
Published: March 2011

ABSTRACTOxygen or chlorine was incorporated into silica glasses by sintering porous soot rods under 02/He or C12/He atmosphere. In case of oxygen, the Schumann-Runge band of 02 molecule was found in VUV region. An absorption band at 4. 8eV having 1. 9eV emission was generated with irradiation of excimer laser. We proposed that such optical properties were due to 02 molecule trapped in glass because they were similar to photochemistry of 02 molecule in the gas phase which could be shown as:When silica glasses were fabricated under chlorine ambient, a minor fraction was found to be present as Cl2 molecule trapped in the glass, which gives the absorption band at 3.8eV.
Glasses for Nonlinear Optics
Authors: Newhouse M. A. 
Published: March 2011

ABSTRACTOur work, in which we have studied optical nonlinearity trends in oxide glasses and the fabrication of optical fibers from high nonlinearity glasses, is reviewed. An oxide glass with a nonresonant nonlinearity Kerr coefficient g equal to 125 × 10−20 cm2/W, which is approximately fifty times larger than that of silica, was identified. Single-mode optical fibers have been fabricated from such high nonlinearity glasses. The predicted enhanced nonlinear properties of the fibers have been demonstrated without any significant degradation due to the nonlinear resonant process of two-photon absorption.
Fused Coupler Optical Switch Using a Photochromic Material
Authors: Kobayashi Yuji , Hosoya Toshifumi , Nonaka Tsuyoshi , Matsuda Yasuo 
Published: March 2011

ABSTRACTAn optical switch based on a single-mode fused coupler has been fabricated. The switch is worked by light induced refractive index change of an organic photochromic compound as cladding material in the coupling region. The splitting ratio of optical output at 1.3 μ m wavelength light can change 44.5%. The optical loss in the switch is less than 0.4
Synthesis, Characterization, and Optical Properties of Inorganic Polymer Films
Authors: Exarhos Gregory J. , Samuels William D. , Burton Sarah D. 
Published: March 2011

ABSTRACTThe linear and non-linear optical response of phosphazene and siloxane polymers and cyclic precursors is influenced by the nature of chemical groups substituted onto the heteronuclear backbone chains. Polymer mechanical properties, chemical stability, and solubility also are affected. Significant variations in both second and third order susceptibilities have been measured for various substituted phosphazene materials. The electron donating tendency of substitutional groups appears to correlate with the measured non-linear optical properties determined by SHG and DFWM experiments in these systems where d¦-p¦ bonding along the polymer chain is important. Approaches to the synthesis, and deposition of these materials as thin films will be discussed. Variations in optical properties are highlighted for several model systems in terms of substitutional group perturbation to the chemical bonding between the chain heteroatoms.
Local structure around Er in MeV Er-implanted silica
Authors: Polman A. , Marcus M. A. , Jacobson D. C. , Poate J. M. 
Published: March 2011

ABSTRACTAmorphous SiO2 films, 10 μm thick, were grown on Si(100) substrates and subsequently implanted with 5.0×1015 Er ions/cm2 at an energy of 3.5 MeV. When optically pumped at λ = 488 nm, the implanted films show a sharply peaked photoluminescence spectrum centred around λ. = 1.54 μm, corresponding to an intra-4f transition of Er3+. Thermal treatment at temperatures above 700 °C is needed to anneal out the implantation-induced defects and attain a maximum PL intensity and luminescence lifetime (15 ms). Extended x-ray absorption fine structure (EXAFS) spectra of Er-implanted bulk silica samples (3.4×1016 ions/cm2, 2.9 MeV) indicate that the Er has six O first neighbours at a distance around 2.25 Å. The results are similar to those for bulk samples doped with Er in the molten phase.
Optical Characteristics of Planar Waveguides in Simox Structures
Authors: Reed G T , Rickman A G , Weiss B L , Namavar F , Cortesi E , Soref R A 
Published: March 2011

ABSTRACTResults are presented for the propagation loss of planar optical waveguides fabricated in SIMOX structures with Si overlayers whose thickness varies from 0.57 μm to 6.0 μm. The results demonstrate that thick Si overlayers are required to produce propagation losses below 1 dB/cm. In addition, the results of the coupling between two vertically integrated waveguides formed using two buried SiO2 layers are also reported.
Investigations on Hydraulically Reactive Glasses in the system CaO-AL2O3-SLO2
Authors: Hommertgen C. , Odler I. 
Published: March 2011

ABSTRACTA series of glasses in the system CaO-Al2O3-SiO2 was synthetized and studied with respect to their hydraulic reactivity. Generally, the initial reactivity is greater but the developed maximum strength is lower in glasses yielding a hydrogarnet phase, as compared to those yielding gehlenite hydrate. Another factor that determines initial reactivity appears to be the cooling rate of the glass melt. After longer hydration times the strength of glass cement pastes starts to decline, apparently due to a recrystallization of the hydrates formed initially.
Synthesis and Properties of Poly(Vinyl Alcohol)/Calcium Aluminate Nanocomposites
Authors: Messersmith Phillip B. , Stupp Samuel I. 
Published: March 2011

ABSTRACTThis paper describes the synthesis, structure and properties of a new layered nanocomposite which may have applications in cementitious systems. This material is one example of a new class of materials which consist of inorganic crystals containing intercalated organic polymer. The nanocomposite is synthesized by precipitating Ca2Al(OH)6[X]·nH2O (X=OH−, CO3−2) in the presence of poly(vinyl alcohol) (PVA). X-ray diffraction analysis indicates that the nanocomposite consists of calcium aluminate layers separated by interlayers containing anions, water and PVA. The intercalation of PVA can only be accomplished during crystal growth and is accompanied by an expansion in layer spacing from ˜8 Å to ˜18 Å. The nanocomposite exhibited enhanced thermal stability and when compacted into a cylinder was found to have more than twice the compressive strength than the pure calcium aluminate.
Multivariate Statistical Analysis of the Wfarddc North American Fly Ash Database
Authors: Pietersen Hans S. , Vriend Simon P. , Mccarthy Gregory J. 
Published: March 2011

ABSTRACTThe database of chemical, mineralogical and physical characteristics of North American Fly ashes, assembled by the WFARDDC in North Dakota, was analyzed using multivariate statistics. Prior to the multivariate analysis, the data were rearranged in subgroups containing information on bulk-chemistry, glass chemistry, mineralogy and ASTM physical test results. These groups were analyzed individually. The multivariate technique used was Fuzzy C-Means Cluster Analysis, combined with Non-Linear Mapping. Analysis of the data-set indicates a relation between glass network former and network modifier content. The database shows that a subdivision on the basis of bulk CaO (< 11%; 11–20%; >20%) correlates well with the ASTM C618 Σ(SiO2 +Al2O3 +Fe2O3) and/or specific gravity. Mineralogical data indicate a subdivision into clusters containing varying amounts of mullite, quartz and/or ferrite spinel and a variety of Ca-containing minerals; high CaO ashes usually have high Ca-mineral contents. Of the CaO containing minerals, only portlandite contributed slightly to the compressive strength as defined by ASTM C618. Analysis of glass chemistry reveals smaller differences in absolute amounts of major oxides than would be expected on the basis of bulk chemistry alone. Surprisingly, the total glass content does not contribute significantly to 28 day compressive strength; multiple regression analysis only indicates a significant relation of particle size and specific gravity with the ASTM Pozzolanic Activity Index (portland cement). The Pozzolanic Activity Index with lime seems to be of limited importance in evaluating the performance of fly ashes as mineral admixtures in concrete. On the basis of the statistical analysis, suggestions for selection of important classifying variables are made.
Magnetic Properties of Low-Ca Fly Ash: A Rapid Tool for Fe-Assessment and a Survey for Potentially Hazardous Elements
Authors: Dekkers M.J. , Pietersen H.S. 
Published: March 2011

ABSTRACTBetween 20 and 50 per cent of the total iron in low-Ca fly ashes resides in low-substitution magnetite spinel with Curie temperatures in between 565 and 590°C. A TEM study reveals that the spinel consists of aggregates of closely spaced spherules of 10 – 30 nm in diameter, which is in complete agreement with rock magnetic determinations. The low-field magnetic susceptibility correlates extremely well with total iron and fairly well with specific heavy metals. Measurement of the magnetic susceptibility may serve as a rapid tool for the evaluation of the speciation of these heavy metals in fly ash.