bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analyses of Pt/Ti Electrodes for Plzt Capacitors
Authors: Olowolafe J. O. , Jones R. E. , Campbell A. C. , Maniar P. D. , Hegde R. I. , Mogab C. J. 
Published: March 2011

AbstractA suitable choice of an electrode material is important for an acceptable electrical contact to a high-permittivity dielectric, such as PLZT. A material which does not form a low-permittivity oxide is necessary, since these dielectrics generally require high temperature deposition or annealing in an oxidizing environment. Platinum, which is one of the few metals that satisfy this requirement, has been widely employed for contacting PLZT. However, for integrated circuit applications, an adhesion layer must be superposed between Pt and the substrate, and Ti is used frequently. Therefore, we have investigated the Pt/Ti combination to determine its suitability as an electrode for contacting PLZT. Using x-ray diffraction, Rutherford backscattering spectrometry, Auger electron microscopy, and scanning electron microscope techniques, interdiffusion of Pt/Ti bilayers has been investigated. Pt/Ti films with or without PLZT overlay were annealed in either O2 or N2 ambients or in N2 followed by O2. Annealing temperatures varied from 500 to 800 °C. It was observed that the anneal ambient has a marked effect on the interdiffusion processes, the reaction products, the morphology of the structures, and the crystallization of PLZT.
Integrated Piezoelectric and Pyroelectric Devices from Thin Film Ferroelectrics
Authors: Sayer M. , Kumar C.V.R. Vasant , Barrow D. , Zou Li , Amm D.T. 
Published: March 2011

AbstractThin PZT films 1-4 μm in thickness prepared by sputtering or sol gel methods allow PZT films to be integrated with silicon technology to achieve piezoelectric or pyroelectric structures having small size or mass. Design criteria, materials and processing techniques for such devices are discussed, and the implementation of small size devices on silicon substrates is demonstrated. Factors of importance are the piezoelectric and pyroelectric characteristics achievable in the films, mechanical strength and fatigue, and the stability and compatibility of the films and electrodes with device fabrication procedures and operating conditions.
Ferroelectricity of Lead-Zirconate-Titanate Thin Films Prepared by Laser Ablation
Authors: Ogawa Toshio , Kidoh Hideo , Yashima Hideyuki , Morimoto Akiharu , Shimizu Tatsuo 
Published: March 2011

AbstractLead-zirconate-titanate films were prepared by excimer laser ablation. The coercive field of films deposited on MgO substrates with an electrode was lower than that of films deposited on sapphire substrates. Laser fluence influenced the grain and crystalline size, resulting in a change in the Ec. Film thicknesses were varied over a range from 0.3 to 2.41μm, with the thinnest film showing a large remanent polarization even at an applied effective voltage of 5V.
Preparation of Epitaxial BaTiO3 Thin Films by Plasma-Enhanced Metalorganic Chemical Vapor Deposition (Pe-Mocvd)
Authors: Chern C.S. , Zhao J. , Norris P. E. , Li Y.Q. , Gallois B. , Kear B. , Luo L. , Maggiore C. J. , Wilkens B. J. 
Published: March 2011

AbstractThe plasma-enhanced metalorganic chemical vapor deposition (PE-MOCVD) process has been successfully used to achieve high quality epitaxial growth of BaTiO3 thin films on (001) LaA103 and (001) NdGaO3 substrates at a substrate temperature of 680°C. The PEMOCVD system, which incorporates a 300-Watt microwave cavity, introduces excited species from an oxygen plasma to lower the required deposition temperature, as compared to thermal MOCVD growth of BaTiO3. X-ray diffraction (XRD) θ-20 scan patterns indicate that there are few randomly oriented grains and impurity phases in the epitaxial BaTiO3 films. Results of XRD ϕ-scans of the BaTiO3 (202) reflection show a modulation pattern of peaks every 90°, which demonstrates that the BaTiO3 thin films have no misorientation along the [100] and [010] directions of the substrates. An XRD ω rocking curve of the BaTiO3 (200) reflection had a narrow FWHM of 0.25°, indicating that the films have a high degree of preferred orientation of <100> perpendicular to the substrates. The high degree of epitaxial crystallinity is further confirmed by Rutherford Backscattering Spectrometry which gives a minimum yield of 7.5% and 11% for the films deposited on LaAIO3 and NdGaO3, respectively. Scanning electron micrographs show that these films have very smooth surface morphologies, which are desirable for device applications.
Lead Scandium Tantalate Thin Films for Thermal Detectors
Authors: Patel A. , Shorrocks N.M. , Whatmore R.W. 
Published: March 2011

AbstractThin films of lead scandium tantalate (Pb(Sc½Ta½)03) (PST) have been prepared by a novel modified sol-gel process. The process involves two deposition steps. In the first, layers of amorphous ScTaO4 are deposited by spin coating a solution of metallorganic compounds of scandium and tantalum. A film of lead oxide is then deposited onto the surface using a solution of lead acetate, and the process repeated to obtain thicker films. After firing the composite film, a pale yellow transparent film of PST is obtained. The films are highly orientated and 100% perovskite.The film's electrical properties have been measured against field and temperature, showing a strong induced pyroelectric response (peak value of 3.8 x 10−3C/m2K), peak permittivities of 4500 and low loss. The figure-ofmerit of these films (11 x 10−5Pa−½) indicates a performance equivalent to conventional bulk ceramic pyroelectric wafers prepared by slicing, lapping and polishing of ceramic blocks.
Quantitative Determination of Er in Silica-Based Matrices
Authors: Oblas Daniel W. , Pink Francis , Singh Mahendra P. , Connolly Joseph , Dugger Donald , Wei T. Michael 
Published: March 2011

ABSTRACTThe distribution and concentration of dopants in the core of an optical fiber, at low concentrations, particularly the rare earth dopants, are difficult to measure quantitatively. However, such information is critical to the determination of absorption cross sections of rare earth dopants in fiber amplifiers and the optimization of their performance. A number of different analytical techniques, such as secondary ion mass spectrometry (SIMS) and the electron probe microanalyzer (EPMA) were used here, along with prepared glass standards, to determine the Er concentration and distribution in optical fiber preforms containing Al, Ge and P. These results were compared with data obtained by neutron activation analysis (NAA) and x-ray fluorescence (XRF) which measure the average concentration of Er in the core. It has been shown that SIMS (and EPMA), in conjunction with NAA data can be used to establish, quantitatively, the Er concentration in the preform core, without the need for glass standards.
Excited State Absorption in Pr3+ Doped Fluorozirconate Glass
Authors: Quimby R. S. , Zheng B. 
Published: March 2011

ABSTRACTThe excited state absorption (ESA) spectrum for Pr3+ doped ZBLAN glass is determined using a new technique based on the McCumber theory [D.E. McCumber, Phys. Rev. 136, A954 (1964)]. ESA peaks at 1380 and 840 nm are found, corresponding to transitions from the 1G4 to the 1D2 and 1I6 levels, respectively. ESA at the fiber amplifier pump wavelength 1.017 μm is found to be very small. The new method is also applied to Er+ doped glass, and good agreement is obtained between the resulting ESA spectrum and previous measurements using a traditional pump-probe technique.
The Role of Glass Composition in the Performance of Er3+-, Nd3+-, and Pr3+-Doped Fiber Amplifiers
Authors: Miniscalco W. J. , Pedersen B. , Zemon S. , Thompson B. A. , Lambert G. , Hall B. T. , Folweiler R. C. , Wei T. , Dakss M. L. , Andrews L. J. 
Published: March 2011

ABSTRACTThe role of glass composition is examined theoretically and experimentally for fiber amplifiers. Simple analysis procedures can be used to set limits on performance and identify more favorable glass types for detailed investigation.
Polymeric Integrated Optics
Authors: Lösch Kurt H. , Kersten Peter , Wischmann Wiltraud 
Published: March 2011

ABSTRACTSince the realization of first polymer channel waveguides in the early 70ths and the market introduction of polymer fibres research work is aiming to increase the integration level of photonic circuits. This paper reports the state of the art in passive and active polymeric integrated optics in view of the requirements for practical applications in telecom and data processing systems.
Segmented proton exchange waveguide on LiNbO3 for SHG using simultaneous modulation of the indices and nonlinear coefficients
Authors: He Q. , Chen S. , Micheli M. P. De , Ostrowsky D. B. , Armani F. , Delacourt D. , Lallier E. , Papuchon M. 
Published: March 2011

ABSTRACTWith proton exchange on LiNbO3 or LiTaO3 it is possible to fabricate waveguides presenting simultaneous modulation of the refractive indices and nonlinear coefficients. This allows us to realize a new kind of Quasi Phase Matching, and we will describe the first experimental results.
Low Loss Rib-Waveguides in SOI
Authors: Schmidtchen J. , Schüppert B. , Splett A. , Petermann K. 
Published: March 2011

ABSTRACTThe realization of single-mode rib-waveguides with dimensions of several micrometers in Silicon-On-Insulator (SOI) is reported. The predicted monomode behaviour is confirmed by comparison of a simulated and a measured nearfield intensity distribution. Waveguide losses below 0.5dB/cm were obtained at wavelengths of 1.3μm and 1.55μm, respectively, independent of the polarization state.
A General Analytical Solution for the Concentration Profiles of Ion-Exchanged Planar Waveguides
Authors: Li Xiaoming , Johnson Paul F. 
Published: March 2011

ABSTRACTDuring the recent years, a great variety of ion-exchange processes, including one-step or two-step electric field assisted ion-exchange processes, have been developed to fabricate different kinds of passive planar glass waveguides, e.g., surface waveguides, which correspond to surface maximum concentration, or buried waveguides, which correspond to inside maximum concentration [1,2,3]. Theoretical calculation of ionic concentration distribution has been of interest since refractive index is generally a linear function of concentration. A general analytical solution to calculate both surface and buried concentration distributions from different ion-exchange processes, however, has not yet been presented. In addition, traditional ion-exchange has been carried out only with constant surface concentration boundary conditions. Little attention has been paid, either experimentally or theoretically, to ion-exchange processes with variable boundary conditions. In fact, the time-dependent surface concentration is experimentally observed for the ion-exchange of GRIN glass in molten salt bath [4]. Very recently, a novel one-step technique [5,6] involving electric field assisted ion-exchange of Na+ in glass by Ag+ from molten AgNO3 bath with decaying silver concentration has been developed to produce buried Ag+ concentration profiles in glass. As the accurate and reproducible processes are very important for fabricating ion-exchanged glass waveguides, theoretical modeling and analysis on the new process are needed.In this paper, the one-dimensional field-assisted linear diffusion equation has been analytically solved by Laplace transformation to theoretically calculate concentration profiles produced by field enhanced ion-exchange process with exponentially decaying surface concentration boundary conditions. The applications of the solution to a variety of ion-exchange processes with different boundary or processing conditions for optical waveguide fabrication have been discussed. The theoretical results prove that the solution is a general analytical solution which can be used to calculate either surface concentration profiles or buried concentration profiles.
Picosecond Nonlinear Optical Response of Copper Clusters Created by Ion Implantation in Fused Silica
Authors: Magruder R. H. , Haglund R. F. , Yang L. , Wittig J. E. , Becker K. , Zuhr R. A. 
Published: March 2011

ABSTRACTWe have embedded nm-size Cu clusters in optically dense, thin (∼ 150 nm) layers using standard ion implantation techniques. The size and size distribution of the clusters can be altered by varying such ion-implantation parameters as total dose and current density. The layers exhibit both a thermo-optic and an electronic nonlinear optical response, depending on the mode of laser excitation. The electronic nonlinearity has a response time no longer than 5 ps.
Optical Waveguides in Thermally Grown SiO2 on Si Using Nitrogen Ion Implantation
Authors: Wong S. P. , Pun E. Y. B. , Lam W. T. , Chung P. S. 
Published: March 2011

ABSTRACTMulti-energy nitrogen implantation into thermally grown SiO2 on silicon substrates has been performed and the optical wave-guiding properties of this structure has been studied. The implantation energy used was in Ie range of 40 KeV to 150 keV, and the doses used were typically 2×1016 to 2×10−2. The energies and doses were chosen to achieve relatively flat implanted nitrogen profiles. It is found that optical waveguides can be formed when the implanted nitrogen concentration is sufficiently high. Both prism-coupling technique and end-fire coupling technique were used to test the implanted waveguides fabricated. Many m-lines including dark modes were observed by the prism-coupling method. This structure is found to be very stable against thermal annealing and there is no significant change observed in the waveguiding properties even after annealing at 1000 °C for four hours. The waveguide loss was found to be typically 0.6 dB/cm before annealing and can be further reduced to about 0.3 dB/cm after annealing.
Cold Cap Grout Formulation for Waste Containment at DOE Site, Hanford, Washington
Authors: Wakeley Lillian D. , Ernzen James J. 
Published: March 2011

ABSTRACTWES developed a grout to be used as a cold (non-radioactive) cap or void-fill material between the solidified low-level waste and the cover blocks of near-surface disposal vaults at the U.S. Department of Energy (DOE) Hanford Facility. The project consisted of formulation and evaluation of candidate grout, followed by a physical scale-model test to verify grout performance under project-specific conditions and provide data to verify numerical models of stresses and isotherms inside the Hanford demonstration vault. Evaluation of unhardened grout included segregation, bleed, flow, and working time. For hardened grout, strength, volume stability, thermal heat rise, and geochemical compatibility with surrogate wasteform grout were examined.The grout was formulated to accommodate unique environmental boundary conditions (vault temperature = 45 °C) and exacting regulatory requirements (mandating less than 0.1% shrinkage with no expansion and no bleeding); and to remain pumpable for a minimum 2 hr. A grout consisting of API Class H cement, an ASTM C 618 Class F fly ash, sodium bentonite clay, and a natural sand from the Hanford area met all performance requirements in laboratory studies.
Degradation of Portland Cements Exposed to Evaporite Brine at Hydrothermal Temperatures
Authors: Krumhansl James L. , Lambert Steven J. 
Published: March 2011

ABSTRACTThe long-term integrity of cementitious materials is of interest where cement is used as part of the isolation system in underground workings sited in evaporite rocks. However, the slow rates of cement/fluid interactions at room temperature provide minimal guidance for predicting long-term cement behavior. To accelerate reactions that degrade cement, hydrothermal brine/cement interaction experiments were carried out at temperatures between 100° and 250° C. The pastes used in these experiments were two batches containing 65 (weight) % Class H cement and 35 % fly ash (one with Class C and one Class F, both with 10 mass equivalent % plaster), and one batch of Type K expansive cement, all with NaCl-saturated mix water. The brine used in testing was based on a composite representation of groundwaters from the Rustler formation of southeastern New Mexico, a mixed evaporite/clastic rock sequence. This brine was sufficiently concentrated that its use afforded an opportunity to study several mechanisms likely to degrade cement performance. At the conclusion of each experiment solid products were characterized and the coexisting fluids analyzed. In general, the cement was extensively altered by the brine at all temperatures assessed. In addition to the expected sulfate attack, it was found that magnesium effectively displaced calcium from the CSH gels that impart strength to cementitious materials. Sodium and potassium did not play a role in altering the cement.
Uptake of Metal Ions by Autoclaved Cement Pastes
Authors: Shi Caijun , Day Robert L. , Wu Xuequan , Tang Mingshu 
Published: March 2011

ABSTRACTThis paper deals with the hydration products and pore structure of Portland cement (PC) and alkali-phosphorus slag cement (APSC) pastes, and the uptake of metal ions (Sr2+, Co2+, Cd2+, and Cu2+) in pastes which have been hydrated at 150°C for 25 days. Results indicate that the hydration products of PC are crystalline Ca(OH)2 and C2SH(A); for APSC the products are poorly crystallized low-basic CSH(B) and crystalline tobermorite. The PC pastes have a lower total porosity than APSC pastes, but the PC pastes consist mainly of larger pores with r> 1000Å, while the APSC pastes consist mainly of smaller pores with r< 100Å. The two types of paste were immersed for 19 days at room temperature in Sr2+, Co2+, Cd2+ and Cu2+ solutions with concentrations of 100, 200, 500 and 1000 ppm. It was found that all Ca(OH)2, in the PC pastes was dissolved. Except for Sr2+, the uptake of metal ions by PC paste is mainly due to the formation of insoluble hydroxides. The uptake of metal ions by APSC pastes is due to physical adsorption and the formation of some insoluble compounds. The APSC pastes show a stable structure after immersion in these metal ion solutions.
The Influence of Moisture on the Expansion of Macro-Defect-Free Cements
Authors: Igarashi H. , Takahashi T. 
Published: March 2011

ABSTRACTMDF(Macro-Defect-Free ) cement pastes, which consist of portland cement and polyvinyl alcohol/acetate, were prepared by varying the temperature during pressing and drying operations. We then examined the expansion of MDF cement pastes at various constant humidities. There was a large difference in expansion above 60%R.H. between samples prepared varying temperature at which samples were pressed. Samples pressed at 90 °C showed less expansion than samples pressed at 40 °C.The pore structure of MDF cement pastes before exposure to moisture was measured by nitrogen adsorption, mercury intrusion porosimetry and image analysis. The properties of a matrix containing polyvinyl alcohol/acetate and cemnt hydrates were also investigated by TEM, IR and XPS.There were not large differences in the result of IR and XPS measurement between the MDF cement pastes prepared at various temperatures. Calcium hydroxide crystal, lying perpendicular to cement particles, were often observed only in the MDF cement pastes pressed at 90 °C which occurs by water absorption, seems to be suppressed by calcium hydroxide crystal.
Processing-Property Interactions in Macro-Defect-Free Cements
Authors: McHugh A. J. , Tan L. S. 
Published: March 2011

ABSTRACTRelationships between mixing conditions, viscoelastic paste properties and flexural strength of hardened matrices have been investigated for an MDF cement. The correlation of paste relaxation times and matrix mechanical properties with mixing intensity suggests the build up and eventual breakdown of a network structure during mixing.
Gel-Cast Organic-Inorganic Systems
Authors: Maes K. , Silsbee M.R. , Roy D.M. , Adair J.H. , Scheetz B.E. 
Published: March 2011

ABSTRACTThe studies reported herein were designed to develop a better understanding of the influence of different crosslinking agents on the polymerization of acrylamide gel systems and upon the resulting physical properties of the composites. Specimens were developed via a gel-casting process for viscoelastic and diametral tensile strength testing and the chemical reactions were monitored by Raman spectroscopy and isothermal calorimetry. The studies have demonstrated the ability to tailor the properties of a gel-cast system over a relatively wide range of reaction rates and the resulting mechanical properties by utilizing small adjustments to the overall chemistry of the system.
New Experimental Techniques for Characterizing Cement-Based Materials
Authors: Jennings Hamlin M. , Sujata K. 
Published: March 2011

ABSTRACTMaterials science is the discipline of studying the relationships between structures and properties of materials. In the case of concrete as an engineering material most research has focussed on properties or on microstructure, but only modest progress has been made on establishing relationships between them. In other words a lot of work has been done in the area of strength, fracture toughness [1], shrinkage [2,3], creep and microcracking [2,4], and microstructure each as somewhat isolated subjects [5]. Microstructure has not been related to properties in a quantitative manner.
Investigation of Pozzolanic Binders Containing Calcined Laterites
Authors: Pera Jean , Ambroise Jean , Momtazi Ali Sadr 
Published: March 2011

ABSTRACTWhen heated at 750°C for five hours, African laterites show good pozzolanic activity. The kaolin content of the materials affects their pozzolanicity as indicated by lime reactivity. Blended cements containing 20, 30, 40, and 50% calcined laterite admixture were examined.The rate of hydration was studied from compressive strength up to 90 days of curing and the hydrates formed as measured by DTA and XRD. The burnt laterite addition considerably reduced calcium hydroxide content and contributed to the formation of hydrated gehlenite (C2 ASH8) and gismondine (CASH).The best compressive streng hs were obtained with blended cements containing 30% calcined laterite. In some cases, there was no more portlandite in binders where the replacement level of cement by burnt laterite was 50% by mass.
Impedance Spectroscopy and the Role of Admixtures in the Hydration of Portland Cement Pastes
Authors: Christensen Bruce J. , Mason Thomas O. , Jennings Hamlin M. 
Published: March 2011

ABSTRACTMeasurements of the bulk electrical properties of cement pastes were made using impedance spectroscopy (IS) and are useful for studying hydration. Normalization of these quantities by dividing out changes in the pore fluid reveals information pertinent to the microstructural development of these materials. In this study, observations are made on the influence of accelerators, retarders and silica fume (SF) on pastes of white and ordinary portland cements (OPC). All systems show variations in the normalized electrical properties at the same degree of hydration, as compared to a control. Changes in the microstructure that are implied by these measurements are consistent with the observations of others.