bluuebunny/crossref_metadata_2025_split huggingface dataset:
In Situ Studies of the Processing of Sol-Gel Produced Amorphous Materials Using Xanes, Saxs and Curved Image Plate XRD
Authors: Pickup DM , Mountjoy G , Newport RJ , Smith ME , Wallidge GW , Roberts MA 
Published: April 2011

ABSTRACTSol-gel produced mixed oxide materials have been extensively studied using conventional, ex situ structural techniques. Because the structure of these materials is complex and dependent on preparation conditions, there is much to be gained from in situ techniques: the high brightness of synchrotron x-ray sources makes it possible to probe atomic structure on a short timescale, and hence in situ. Here we report recent results for mixed titania- (and some zirconia-) silica gels and xerogels. Titania contents were in the range 8–18 mol%, and heat treatments up to 500°C were applied. The results have been obtained from intrinsically rapid synchrotron x-ray experiments: i) time-resolved small angle scattering, using a quadrant detector, to follow the initial stages of aggregation between the sol and the gel; ii) the use of a curved image plate detector in diffraction, which allowed the simultaneous collection of data across a wide range of scattering at high count rate, to study heat treatments; and iii) x-ray absorption spectroscopy to explore the effects of ambient moisture on transition metal sites.
Maximum Entropy Method Charge Density Distributions of Novel Thermoelectric Clathrates
Authors: Iversen B. , Bentien A. , Palmqvist A. , Bryan D. , Latturner S. , Stucky G.D. , Blake N. , Metiu H. , Nolas G. S. , Cox D. 
Published: April 2011

ABSTRACTRecently materials with promising thermoelectric properties were discovered among the clathrates. Transport data has indicated that these materials have some of the characteristics of a good thermoelectric, namely a low thermal conductivity and a high electrical conductivity. Based on synchrotron powder and conventional single crystal x-ray diffraction data we have determined the charge density distribution in Sr8Ga16Ge3Ousing the Maximum Entropy Method. The MEM density shows clear evidence of guest atom rattling, and this contributes to the reduction of the thermal conductivity. Analysis of the charge distribution reveals that Sr8Ga16Ge30contains mixed valence alkaline earth guest atoms. The Sr atoms in the small cavities are, as expected, doubly positively charged, whereas the Sr atoms in the large cavities appear negatively charged. The MEM density furthermore suggests that the Ga and Ge atoms may not be randomly disordered on the framework sites as found in the conventional leastsquares refinements.
Structure of the Near-Surface Waveguide Layers Produced by Diffusion of Titanium in Lithium Niobate
Authors: Avrahami Y. , Zolotoyabko E. , Sauer W. , Metzger T. H. , Peisl J. 
Published: April 2011

ABSTRACTTitanium-induced structural modifications in thin waveguide layers of lithium niobate have been investigated by grazing incidence diffraction and complementary thin film techniques. The study was focused on the high-temperature phase transformation in this system and its influence on the lattice parameter changes, depending on the annealing time.
Nondestructive Determination of the Depth of Different Texture Components in Polycrystalline Samples
Authors: Patterson C.R. , Ignatiev K.I. , Guvenilir A. , Haase J.D. , Morano R. , Rek Z.U. , Stock S.R. 
Published: April 2011

ABSTRACTThe surface and the center average textures (macrotexture) of plates of many alloys differ substantially, and nondestructive methods for determining the depth of different texture components would be very useful in various applications. This report evaluates one method based on recording microbeam transmission Laue patterns as a function of sample-detector separation and on tracing the diffracted rays back to their physical origin. Polychromatic synchrotron x-radiation and absorption edge filters are used. Results from sections of Al-Li 2090 T8E41 plates are reported, and limitations of the ray tracing technique are discussed
The Influence of Desulfovibrio Desulfuricans on Neptunium Chemistry
Authors: Soderholm L. , Williams C.W. , Antonio Mark R. , Tischler Monica Lee , Markos Michael 
Published: April 2011

ABSTRACTBiotic Np(V) reduction is studied in light of its potential role for the environmental immobilization of this hazardous radionuclide. The speciation of Np inDesulfovibrio desulfuricanscultures is compared with Np speciation in the spent medium and in the uninoculated medium. Precipitates formed in all three samples. Optical spectroscopy, x-ray diffraction, and x-ray absorption near edge structure (XANES) were used to determine the Np speciation. After 5 days of incubation, there was very little Np left in solution, which was present as Np(V). The precipitate that formed in all samples is an amorphous Np(IV) species, establishing that Np(V) is almost quantitatively reduced. These results demonstrate that the reduction of Np is independent ofDesulfovibrio desulfuricans.The underlying chemistry associated with these results is discussed.
Keys to the Enhanced Performance of Mercuric Iodide Radiation Detectors Provided by Diffraction Imaging
Authors: Steiner Bruce , van den Berg Lodewijk , Laor Uri 
Published: April 2011

ABSTRACTHigh resolution monochomatic diffraction imaging is playing a central role in the optimization of novel high energy radiation detectors for superior energy resolution at room temperature. In the early days of the space program, the electronic transport properties of mercuric iodide crystals grown in microgravity provided irrefutable evidence that substantial property improvement was possible. Through diffraction imaging, this superiority has been traced to the absence of inclusions. At the same time, other types of irregularity have been shown to be surprisingly less influential. As a result of the knowledge gained from these observations, the uniformity of terrestrial crystals has been modified, and their electronic properties have been enhanced. Progress toward property optimization through structural control is described.
x-ray Absorption Characterization of Diesel Exhaust Particulates
Authors: Nelson A. J. , Ferreira J. L. , Reynolds J. G. , Schwab S.D. , Roos J. W. 
Published: April 2011

ABSTRACTWe have characterized particulates from a 1993 11.1 Detroit Diesel Series 60 engine with electronic unit injectors operated using fuels with and without methylcyclopentadienyl manganese tricarbonyl (MMT) and overbased calcium sulfonate added. x-ray photoabsorption (XAS) spectroscopy was used to characterize the diesel particulates. Results reveal a mixture of primarily Mn-phosphate with some Mn-oxide, and Ca-sulfate on the surface of the filtered particulates from the diesel engine.
XANES Analysis of BCC/FCC Two-Phase Binary Alloys
Authors: Schilling P.J. , Tittsworth R.C. , Ma E. , He J.-H. 
Published: April 2011

ABSTRACTA critical factor in the characterization of two-phase binary alloy systems is the determination of the phase fractions and compositions of the two coexisting solid solutions for any given overall composition of the two-phase mixture. In some systems, for example nanocrystalline alloys formed by high-energy ball-milling, these parameters are difficult to attain by traditional techniques like x-ray diffraction. A new technique has been developed to obtain these quantities indirectly from x-ray absorption near edge structure (XANES) data collected at the two relevant absorption edges, with the formulation of this technique presented here in detail. The technique has been tested using Fe-Ni fcc and bcc standards and the results indicate that the method is accurate to within 5%. This method has been applied to two-phase (f.c.c. and b.c.c.) binary alloys formed by ball-milling of Cu100-xFex(x = 50-80).
Spectroscopic Characterization of Mixed Titania-Silica Xerogel Catalysts
Authors: Holland MA , Pickup DM , Mountjoy G , Tsang SC , Wallidge GW , Newport RJ , Smith ME 
Published: April 2011

ABSTRACTThe synthesis of high surface area (TiO2)0.18(SiO2)0.82xerogels has been achieved using the sol-gel route. Heptane washing was used before the drying stage to minimise capillary pressure and hence preserve pore structure and maximise the surface area. The as-prepared xerogels were tested for their catalytic activity using the epoxidation of cyclohexene with tert-butyl hydrogen peroxide (TBHP) as a test reaction. Surface areas up to 450 m2g-1 were achieved with excellent selectivities and reasonable percent conversions. SAXS data has identified that heptane washing during drying, in general, results in a preservation of the pore structure, and produces more effective catalysts with higher surface areas and larger pore diameters. Fr-IR spectroscopy has revealed that the catalytic activity is dependant upon the number of Si-O-Ti linkages, inferring intimate mixing of the precursors at the atomic level. XANES data reveals the presence of reversible 4/6-fold Ti sites that are thought to be ‘active’ catalytic sites. The most effective catalyst was produced with a calcination temperature of 500°C, and a heating rate of 5 °Cmin-l
An Inelastic Nuclear Resonant Scattering Study of Partial Entropies of Ordered and Disordered Fe3Al
Authors: Fultz B. , Sturhahn W. , Toellner T. S. , Alp E. E. 
Published: April 2011

ABSTRACTInelastic nuclear resonant scattering spectra were measured on alloys of Fe3Al that were chemically disordered, partially-ordered, and DO3-ordered. The phonon partial DOS for 57Fe atoms were extracted from these data, and the change upon disordering in the partial vibrational entropy of Fe atoms was obtained. By comparison to previous calorimetry measurements, it is shown that the contribution of the Fe atoms to the vibrational entropy is a factor of 10 smaller than that of the Al atoms. With the assistance of Born – von Kárán model calculations on the ordered alloy, it is shown that differences in the vibrational entropy originate primarily with changes in the optical modes upon disordering. The phonon DOS of 57Fe was found to change systematically with chemical short range order in the alloy. It is argued that changes in the vibrational entropy originate primarily with changes in the chemical short-range order in the alloy, as opposed to long-range order.
Quantitative Contact Spectroscopy and Imaging by Atomic-Force Acoustic Microscopy
Authors: Arnold W. , Amelio S. , Hirsekorn S. , Rabe U. 
Published: April 2011

ABSTRACTAtomic Force Acoustic Microscopy is a near-field technique which combines the ability in using ultrasonics to image elastic properties with the high lateral resolution of scanning probe microscopes. We present a technique to measure the contact stiffness and the Young's modulus of sample surfaces quantitatively with a resolution of approximately 20 rum exploiting the contact resonance frequencies of standard cantilevers used in Atomic Force Microscopy. The Young's modulus of nanocrystalline ferrite films have been measured as a function of oxidation temperature. Furthermore images showing the domain structure of piezoelectric lead zirconate titanate ceramics have been taken.
Precise Determination of Thin Metal Film Thickness With Laser-Induced Acoustic Grating Technique
Authors: Maznev A.A. , Banet M.J. , Gostein M. , Hanselman R.B. , Joffe M.A. , Sacco R. , Nelson K.A. 
Published: April 2011

ABSTRACTAn all-optical technique based on laser excitation and detection of surface acoustic waves is capable of precise, fast, noncontact and nondestructive measurements of metal film thickness. The technique is integrated into a compact and robust instrument. Applications to metal interconnect process control in integrated circuit technology are presented.
Characterization of nitrided silicon-silicon dioxide interfaces
Authors: Polignano M. L. , Alessandri M. , Brazzelli D. , Crivelli B. , Ghidini G. , Zonca R. , Caricato A. P. , Bersani M. , Sbetti M. , Vanzetti L. , Xing G. C. , Miner G.E. , Astici N. , Kuppurao S. , Lopes D. 
Published: April 2011

ABSTRACTA newly-developed technique for the simultaneos characterization of the oxide-silicon interface properties and of bulk impurities was used for a systematic study of the nitridation process of thin oxides. This technique is based upon surface recombination velocity measurements, and does not require the formation of a capacitor structure, so it is very suitable for the characterization of as-grown interfaces.Oxides grown both in dry and in wet enviroments were considered, and nitridation processes in N2O and in NO were compared to N2 annealing processes. The effect of nitridation temperature and duration were also studied, and RTO/RTN processes were compared to conventional furnace nitridation processes.Surface recombination velocity was correlated with nitrogen concentration at the oxide-silicon interface obtained by Secondary Ion Mass Spectroscopy (SIMS) measurements. Surface recombination velocity (hence surface state density) decreases with increasing nitrogen pile-up at the oxide-silicon interface, indicating that in nitrided interfaces surface state density is limited by nitridation. NO treatments are much more effective than N2O treatments in the formation of a nitrogen-rich interface layer and, as a consequence, in surface state reduction.Surface state density was measured in fully processed wafers before and after constant current stress. After a complete device process surface states are annealed out by hydrogen passivation, however they are reactivated by the electrical stress, and surface state results after stress were compared with data of surface recombination velocity in as-processed wafers.
Experimental Simulation of Contamination Arising From Electro Rocket Engine-Jet on Surface of Spacecraft Units
Authors: Chirov A. , Nadiradze A. , Shaposhniko V. , Egorov V. 
Published: April 2011

ABSTRACTUnder conditions of a vacuum simulation it was investigated how electric rocket thruster (ERT) SPT-70 contaminates space craft (SC) surfaces. The contamination content in the ERT jet was studied by using solid targets. The film composition was analysed by Rutherford backscattering spectroscopy (RBS) He+ ions and nuclear reaction analysis (NRA) with H+ ions methods. Using the results of this analysis a preliminary estimation of the composition and the angular distribution of contaminated components in the ERT jet were carried out.
Thermal Penetration Times as a Nondestructive Measure of Orientation in Polyimide Film
Authors: Chandler C. , Mathis N.E. , Samuels R.J. 
Published: April 2011

ABSTRACTMaterial properties depend on their fabricated structure and orientation. It is thus important to develop rapid nondestructive techniques that will both allow determination of the orientation fabricated, and identify any changes that occur over time as a result of subsequent in service environmental conditions.The present study examines the relationship between the thermal penetration time and planarity in polyimide films. Polyimides are advanced materials that have good high temperature stability, excellent dimensional stability, and excellent mechanical, electrical, and chemical resistance properties. The samples tested were specially prepared to range in orientation from three dimensionally random to highly planar. The molecular structure and orientation in the polyimide film was characterized by polarizing microscope techniques, while the thermal penetration time measurements utilized a new rapid nondestructive modified hot wire instrument.This correlation will be the first time thermal penetration time has been measured by modified hot wire techniques and related to the internal structure of a polyimide. The work contributes to a deeper theoretical understanding of heat transfer mechanisms as they relate to orientation. Thermal penetration time evaluation could provide a new tool in the arsenal of structural characterization techniques.This relationship between thermal penetration time and orientation is key for film manufacturers. Such a correlation has potential to speed the development cycles of new materials and assure properties during production and end-use applications.
IRS and ESR Characterizations of Nanocomposite Thin Films Derived From Alkanethiolates and Gold Nanoparticles
Authors: Zheng W. X. , Leibowitz F. L. , Maye M. M. , Gilbert D. C. , Doetschman D. C. , Zhong C. J. 
Published: April 2011

ABSTRACTA key to the ultimate technological applications of core-shell nanoparticle materials is the understanding of the structure-property correlation. This work focuses on the characterizations of the structural properties for composite thin films derived from gold nanoparticles and thiolates using infrared reflectance spectroscopic (IRS) and electron spin resonance (ESR) techniques. IRS provides information on molecular packing and ordering of the shell components in the films, which relates to the molecular interactions and interfacial reactivities. ESR probes the conduction electron spin resonance properties of the nanosized cores, which can be correlated with the network or environmental electronic effects on the crystal cores. Results are discussed in terms of their correlation with the nanoparticle core sizes and the organic shell functionality.
Characterization of Ni- and Ni(Pt)-Silicide Formation on Narrow Polycrystalline Si Lines by Raman Spectroscopy
Authors: Lee P. S. , Mangelinck D. , Pey K. L. , Ding J. , Osipowicz T. , Ho C. S. , Chen G. L. , Chan L. 
Published: April 2011

ABSTRACTThe formation and thermal stability of Ni- and Ni(Pt) silicide on narrow polycrystalline Si (poly-Si) lines have been investigated using the non-destructive micro-Raman technique. The presence of Ni or Ni(Pt)Si on poly-Si lines with linewidths ranging from 0.5 gtm to 0.25 μm has been monitored by a distinct Raman peak at around 215 cm−1. Ni(Pt)Si was clearly identified to be present up to a RTA temperature of 900°C on narrow poly-Si lines as compared to pure NiSi which was found only up to 750°C. Raman scattering from the 100×100 μm2 poly-Si pads showed the formation of NiSi2 at 750°C for pure Ni-salicidation and 900°C for Ni(Pt)-salicidation respectively. The difference in the stability of NiSi on the poly-Si pads and lines is discussed in terms of agglomeration, inversion and/or nucleation of NiSi2that could be due to difference in nucleation sites and/or stress. In addition, a correlation between the line sheet resistance and the presence of Ni silicide was found using micro-Raman mapping along single poly-Si lines.
Characterization of Copper Surfaces Used in Electronic Circuit Boards by Reflectance FT-IR
Authors: Sloan James M. , Pergantis Charles G. 
Published: April 2011

ABSTRACTOrganic and organo-metallic coatings are presently being applied over bare copper as an approach to improve the co-planarity of circuit boards. Conformal organic solderability preservative coatings (OSP) are environmentally and economically advantageous over the more commonly used lead based coatings [1-2]. Problems arise in assessing the solderability of the bare copper and the integrity of the organic coating.Specular reflectance Fourier transform infrared spectroscopy (FT-IR) was utilized to monitor and evaluate the formation of Cu oxides occurring on copper substrates used in the manufacturing of electronic circuit boards. Previous studies reported the utility of this technique[3,4]. By measuring the oxide and protective coating characteristics of these surfaces, their solderability performance can rapidly be evaluated in a manufacturing environment. OSP coated test specimens were subjected to hot-dry and hot-wet environmental conditions using MIL-STD-202F [5] and MIL-STD-883E [6] as guides.The resultant FT-IR spectra provided clear evidence for the formation of various Cu oxides at the Cu/OSP interface over exposure time, for the samples subjected to the hot-dry environment. IR spectral bands consistent with O-Cu-O and Cu202 formation appear, while very minimal deterioration to the OSP coating was observed. The appearance of the Cu oxide layers grew steadily with increased environmental exposure. Specimens subjected to the hot-wet conditions showed no significant signs of deterioration. The IR data can be directly correlated to solderability performance as evaluated by wet balance testing.
In Situ Monitoring of MOCVD of Aluminum Nitride by Optical Spectroscopies
Authors: Allen S.C. , Richardson H.H. 
Published: April 2011

ABSTRACTTrimethylaluminum and ammonia were used as precursors in the high temperature (900°C) deposition of AIN on silicon at vacuum pressure. The emitted radiation was collected in situ by a FTIR spectrometer. Film thickness was monitored in situ by interference oscillations in a red diode laser beam reflected off the sample. The thickness measurements were correlated with IR emission spectra from the emerging AIN film, and a principal component analysis (PCA) and principal component regression (PCR) were performed on the data.
High-Frequency Stroboscopic X-ray Topography Under Surface Acoustic Wave Excitation
Authors: Zolotoyabko E. 
Published: April 2011

ABSTRACTThe pulse structure of synchrotron radiation was used in order to carry out timeresolved x-ray diffraction imaging of high-frequency (up to 0.6 GHz) surface acoustic waves propagating through a single crystal. In x-ray topographs, recorded in the stroboscopic mode, the short wavelength (down to 6 μm) individual wave fronts are clearly visible, providing information on the acoustic scattering processes with participation of lattice defects.
Chemical and Structural Characterization of Ultrathin Dielectric Films Using AEM
Authors: Scott J.H.J. , Windsor E.S. 
Published: April 2011

ABSTRACTThe structure of ultrathin silicon oxynitride films, used as gate dielectrics in integrated circuits (ICs), is studied using analytical electron microscopy (AEM). Laterally homogeneous blanket films approximately 2 nm in thickness are characterized in cross section using a 300 keV field emission TEM/STEM. High resolution imaging (HRTEM) is used to investigate the accuracy and precision of film thickness measurements and their comparability to other techniques such as secondary ion mass spectrometry, spectroscopic ellipsometry, x-ray reflectivity, x-ray photoelectron spectroscopy, and medium energy ion scattering. A two dimensional magnification calibration scheme that fits a pair of basis vectors to experimental images is presented, and integrated intensity profiles are used to define film boundaries for measurement. These image processing tools simultaneously improve the repeatability of the measurements and remove subjective operator bias from the measurement process.
Analysis of MOS Device Capacitance-Voltage Characteristics Based on the Self-Consistent Solution of the Schrödinger and Poisson Equations
Authors: Raynaud C. , Autran J.L. , Masson P. , Bidaud M. , Poncet A. 
Published: April 2011

ABSTRACTThe one-dimensional Schridinger and Poisson equations have been numerically solved in metal-oxide-semiconductor devices using a three-point finite difference scheme with a non-uniform mesh size. The capacitance-voltage characteristic of the structure has been calculated via this self-consistent approach and results have been compared with data obtained from the resolution of Poisson equation using different approximated methods based on the Boltzmann statistic with and without a first order quantum effect correction or the exact Fermi-Dirac statistic. The present work permits to evaluate and quantify the errors made by these approximations in determining the thickness of ultra-thin oxides.