bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Model of Thermal Stress Development in Microelectronic Components
Authors: Scott Geoffrey C. , Astfalk Greg 
Published: March 2011

AbstractA model to characterize the development of thermal stresses in printed wiring board (PWB)-mounted multilayer ceramic capacitors (MLCC's) is presented. The model is developed analytically using uncoupled, quasi-static thermoelastic theory. Both the actual 2D geometry and mechanical and thermal properties of real MLCC-PWB structures are incorporated in the model. A particular method for solving the model equations is presented and implemented. Preliminary numerical results indicate that the values and spatial patterns of stress are in agreement with data available in the experimental literature.
Mechanisms for Conduction Pathway Formation in Polymer Encapsulants
Authors: Anderson J. E. , Hoffmann D. A. , Frank C. W. , Bousse L. J. 
Published: March 2011

AbstractThis article concerns physicochemical mechanisms leading to formation of local heterogeneous structures in bulk polymers. Previous experimental work suggests that such heterogeneities are related to ionic conduction and electrochemical attack on encapsulated microelectronics. Six mechanisms are discussed: (a) Macrosyneresis; (b) Osmotic swelling; (c) Liquid-liquid phase separation; (d) Microsyneresis; (e) Polymer fracture during solvent sorption/desorption; (f) Polymer-substrate interactions.
Preparation of Spherical Titania Particles from Inorganic Precursor by Homogeneous Precipitation
Authors: Kato A. , Takeshita Y. , Katatae Y. 
Published: March 2011

ABSTRACTSpherical titania particles can be prepared in a short time period from an aqueous solution of TiOSO4 by homogeneous precipitation using urea at 70–90°C. Although the hydrolysis of TiOSO4 continues to a considerable extent even in the absence of urea, the presence of urea is essential for the formation of spherical particles. The average particle size produced was l–4μm and changed mainly with the concentration of TiOSO4. As-synthesized powders are amorphous hydrates of titania containing sulfate group and crystallize by calcination into anatase(>500°C) and rutile(>900°C). In calcination, the particles shrink, but hold their original spherical shapes.
Sol-Gel Networks: Fundamental Investigations of the Chemistry of Sol-Gel Silicate Glasses and Poly(Siloxane) Toughened Silicates
Authors: Spinu M. , Mcgrath J. E. 
Published: March 2011

ABSTRACTThe low-temperature sol-gel process opens a number of new materials possibilities for generation of glasses with predetermined properties by the incorporation of organic modifiers into the network. Polysiloxanes are potentially interesting organic modifiers for toughening and possibly surface-modifying the silicate networks. Some fundamental studies of the hydrolysis and condensation processes in a tetramethylorthosilicate (TMOS) system, in the absence of added catalyst, have been conducted using 1H and 29Si NMR. The effects of some of the reaction parameters and processing conditions for the subsequent conversion of the gel to monolithic dried gels by heat treatment have been investigated by techniques such as thermal analysis and mass spectroscopy. Procedures which employ mild pressures have been established that permit the generation of monolithic products which show greatly reduced cracking tendencies. Finally, methoxy functionalized poly(dimethylsiloxane) oligomers that can react into the sol-gel network have been prepared. The intermediates are commercially accessible and the process is scaleable. Utilization of a catalyst-free system eliminates the tendency of the siloxane modifier to undergo undesired rearrangements that are known to occur in the presence of strong acids or bases.
Barriers to the Nucleation of Methyl Groups on the Diamond (111) Surface
Authors: Valone Steven M. 
Published: March 2011

ABSTRACTQuestions about the mechanism of diamond film growth by low-pressure, plasma-assisted chemical vapor deposition methods have persisted for some time now. As an attempt to explore one aspect of the problem, we examine the energetics of several adsorbed diamond (111) surfaces. The adsorbates are mixtures of methyl groups and hydrogen atoms. The model for these systems is the molecular orbital hamiltonian of Dewar and coworkers.From these calculations we find that H adsorbtion is preferred due both to bond energy and steric effects. Thus, nucleation of a cluster of three or more methyl groups, as assumed in earlier work, is energetically very demanding.
Processing of SiC-Whisker Reinforced Si3N4
Authors: Hoffmann M. J. , Nagel A. , Petzow G. 
Published: March 2011

ABSTRACTCold isostatic pressed (CIP) and slip cast Si3N4 composite materials containing up to 20 vol.% SiC-whiskers were densif led by pressureless
sintering and post-HIPing. The slips were characterized by viscosimetry and showed no influence of whisker loading on the rheology of the highly concentrated aqueous suspensions up to 15 vol.! whiskers. During casting the whiskers were preferentially aligned parallel to the mould surface and the CIPed samples showed a 3-dimensional random whisker distribution. The influence of the whisker length and orientation on the densification behaviour was studied in a high-temperature dilatometer. While the CIPed samples exhibit an isotropic shrinkage behaviour, the slip cast samples showed a strong shrinkage anisotropy with a maximum linear shrinkage of 21% perpendicular and only 7% parallel to the whisker plane for the samples with 20 vol.% whiskers. With increased whisker loading, the sintered densities decreased from 0.99 to 0.88 fractional density. The poor sinterability of the composites was attributed to the sintering stresses around the non-sintering SiC- whiskers and the formation of a whisker network which inhibits further shrinkage in the final stage of sintering. Thermodynamic calculations show the optimum fabrication conditions for SIC-whisker reinforced Si3N4-composites.
Structural Transitions induced by Colloidal Interactions in Ceramic Dispersions
Authors: Rajagopalan Raj 
Published: March 2011

ABSTRACTA discussion of the formation of periodic colloid structures, liquid-like ordering, and compact and fractal aggregates caused by colloidal forces in ceramic dispersions is presented. Construction of phase diagrams based on simple forms of repulsive potentials is often not adequate, and it is important to include appropriate attractive interactions in the theoretical analyses. Examples of radial distribution functions, osmotic prsueadphase diagrams are given for dispersions interacting through Derjaguin-Landau-Verwey-Overbeek potentials. Densification of colloidal aggregates dlue to positional relaxation and the effects of such densification on the structure of the aggregates are discussed.
Flow of Dispersions Near Close Packing
Authors: Marshall L. , Zukoski C. F. 
Published: March 2011

ABSTRACTThe flow of hard sphere-like suspensions near close packing is explored. The change in viscosity with stress and volume fraction shows that at volume fractions above 0.5 shear thickening occurs and that the characteristic shear rates for shear thinning and shear thickening decrease rapidly above this volume fraction. The creep compliance is well characterized by a stretched exponential relaxation time spectrum above volume fractions of 0.52. These results suggest that the limiting volume fraction where the zero shear rate viscosity diverges is determined by a liquid/glass phase transition very similar to that predicted for hard sphere liquids.
Electronic Properties of some Ternary and Quaternary Oxides of the VIII B and I B Transition Elements: Application to High TcSuperconductivity
Authors: Pouchard M. , Grenier J-C. , Doumerc J-P. , Demazeau G. , Chaminade J-P. , Wattiaux A. , Dordor P. , Hagenmuller P. 
Published: March 2011

ABSTRACTIn the scope of the Goodenough model, a brief review of the electronic properties of some 3d transition elements (M = Fe, Co, Ni and Cu ) is given; the main relevant electronic and structural parameters are emphasized. Then a special attention is focussed on N/(N−1) and N/(N−2) electron mixed valence compounds.Finally some particular features of copper are discussed and their relevance to high Tc superconductors is pointed out:-the srong covalency of Cu-O bondings involving a possible delocalization of the hole between trivalent copper and oxygen,-the existence of low and high spin electronic configurations for CuIII,-the disproportionation of Cu2+and its role in the formation of hole pairs,Cu-O distances very close for the three successive oxidation states of copper favouring the disproportionation process.
Annealing and Strain Effects on Tl-Ba-Ca-Cu-O Crystals and Ceramics
Authors: Venturini E. L. , Morosin B. , Ginley D. S. , Kwak J. F. , Schirber J. E. , Baughman R. J. , Graham R. A. 
Published: March 2011

ABSTRACTSuperconducting transition temperatures (Tc'S) in the Tl-Ba-Ca-Cu-O system are shown to be a function of processing for both single crystals and bulk ceramics. Crystals with the identical structural phase and nominal composition but slightly different lattice constants can have significant differences in Tc. We report the effects of high temperature annealing in vacuum or flowing oxygen on Tc for single crystal plates of two common phases with nominal stochiometries Tl2Ba2Ca1Cu2O8 and Tl2Ba2Ca2Cu3O10. Contradictory results on nominally similar crystals suggest that strain, Tl content and TI/Ca site disorder are as important as the oxygen stoichiometry in determining Tc This interpretation is supported by complementary annealing studies in bulk ceramic, including a powder where Tc increased by 5 K following high-pressure shock loading which introduced substantial residual strain.
Synthesis and Properties of the High Tc Bi-Pb-Sr-Ca-Cu-O Superconductors
Authors: Endo Utako , Koyama J. , Kawai T. , Okazaki N. , Kitazawa K. , Matsui Y. 
Published: March 2011

ABSTRACTA single high Tc phase of Bi-Pb-Sr-Ca-Cu-O superconductor was obtained by following proper synthetic conditions:(a)addition of Pb, (b)proper starting composition, (c)codecomposition method, (d)sintering under low oxygen partial pressure and (e)long sintering. The composition analysis showed that every atomic site might be occupied by some element and there might not be defects or excess atoms in the structure. The hole donor in these samples is considered to be Pb on the Bi site and hole concentration seems to be, to some extent, controlled by the Pb content. A phase with four CuO2 layers have possibly grown on the surface of the grains of thi high Tc phase.
Structural and Electronic Relationships in the High-Temperature Copper-Based Superconductors
Authors: Torardi C.C. , Jung D. , Kang D.B. , Ren J. , Whangbo M.-H. 
Published: March 2011

ABSTRACTAtomic displacements from the ideal rock-salt positions in the Tl-, Bi-, and Pb-O layers of the Cu-based high-Tc super-conductors affect the electronic nature of these oxides. When distortions in the Bi-O layers of Bi2Sr2CaCu2O8 are considered, the bottom of the Bi 6p band is found to lie more than 1 eV above the Fermi level. Displacements in the double Tl-O layers of Tl2Ba2Can−1CunO2n+4 places the bottom of the Tl 6s bands significantly below the Fermi level showing that electrons can be removed from the x2-y2 bands of the CuO2 layers. However, this is not the case for the thallium-oxygen single layers of Tl2Ba2Can−1CunO2n+3. Correlations between the superconducting transition temperatures, Tc, and the in-plane Cu-O bond lengths, rCu−O', of the Tl- and Bi- based copper-oxide super-conductors reveal Tc vs rCu−O characteristics similar to those found for La2−xSrxCuO4.
Barium Potassium Bismuth Oxide Synthesis and Physical Properties
Authors: Ott K. C. , Hundley M. F. , Kwei G. H. , Maley M. P. , McHenry M. E. , Peterson E. J. , Thompson J. D. , Willis J. O. 
Published: March 2011

ABSTRACTA series of compounds Ba1−xKxBiO3 have been prepared and characterized over the range of compositions ranging from x = 0.3 to 0.5. A neutron powder diffraction analysis has been carried out for the composition x = 0.4 at room temperature and at 10 K. Examination of the superconducting properties as a function of x indicates superconductivity occurs over a narrow range of compositions close to x = 0.4, with Tc of 29 K. Specific heat measurements indicate conventional electron-phonon interactions may play a role in promoting superconductivity in Ba.6K.4BiO3. Magnetization loops and examination of the time dependent magnetization indicate that Ba.6K.4BiO3 has a low value of Jc due to very weak pinning.
Some Aspects of the Nonstoichiometric and Thermodynamic Behavior of the YBa2Cu3Oz System
Authors: Tetenbaum M. , Curtiss L. , Czech B. , Tani B. , Blander M. 
Published: March 2011

ABSTRACTThe nonstoichiometric and thermodynamic behavior of the YBa2Cu3Ox system as a function of oxygen partial pressure and temperature is being investigated by means of a coulometric titration technique. The oxygen content of the superconductor can be varied coulometrically by well-defined small amounts and the equilibrium partial pressures determined from the EMF. The oxygen stoichiometry in YBa2Cu3Ox as a function of oxygen partial pressure shows a change of curvature around x = 6.55–6.75 and an inflection around x ≅ 6.65 at temperatures between 400–500°C. These new low temperature data are consistent with the presence of a miscibility gap at lower temperatures, which is similar to that postulated in several theoretical papers.
Oxygen Nonstoichiometry and Related Problems of High-TcOxide Superconductors Investigated by Thermogravimetry
Authors: Kishio K. , Hasegawa T. , Suzuki K. , Kitazawa K. , Fueki K. 
Published: March 2011

ABSTRACTThermogravimetry (TG) is a sensitive and powerful tool for investigation of oxygen nonstoichiometry and related properties in mixed-valence oxide systems and has been extensively applied to a series of high-Tcoxide superconductors. Nonstoichiometry, phase stability ranges, and oxygen diffusion as investigated mainly through the TG technique in several systems of high-Tcoxides are reviewed.
Preparation and Characterization of Ion Beam Assisted Aluminum Oxide Films
Authors: Hirvonen James K. , Tetreault T.G. , Parker G. , Revesz P. , Land D. , Price J. , Simons D. , Stern S. 
Published: March 2011

ABSTRACTThe ion beam assisted deposition (IBAD) technique has been employed to make aluminum oxide optical coatings. Deposition variables include aluminum oxide evaporant to oxygen ion beam flux ratios, substrate temperature, and ion energy. Characterization included optical ellipsometry, ion beam analysis, and adhesion tests. Films deposited with the aid of ions exhibited the highest refractive indices and best adhesion to their substrates.
Ion-Beam Synthesis of Buried Yttrium Silicide
Authors: Alford T.L. , Barbour J.C. 
Published: March 2011

ABSTRACTBuried single-crystal YSi1.7 layers have been synthesized using high fluence implants of 330 keV yttrium ions into (111) Si held at 450°C followed by post-implant anneals of 1000°C . Rutherford backscattering spectrometry showed that an implant fluence of 3.6 X 1017 Y/cm2 forms a continuous layer of uniform thickness. Whereas, implant fluences of 1 — 2 x 1017 Y/cm2 form a thin continuous YSi1.7 layer with what are believed to be Y-silicide precipitates above and below the YSi1.7 layer. Strains resulting from the YSi1-7 layers were evaluated from x-ray rocking curves using a double crystal diffractometer.
Formation of Buried Oxynitride Layer into Silica Glass using Ion Beam
Authors: Oyoshi Keiji , Tagami Takashi , Tanaka Shuhei 
Published: March 2011

ABSTRACTBoth silicon and nitrogen implanted silica glasses were characterized by SIMS, XPS and SEM. Bubbles appeared in the implanted region at the high dose implantation (the silicon to nitrogen dose ratio is 0.75 and the total dose is 4×10 ions/cm2). Suppression methods of bubble formation were discussed concerning about the nitrogen implantation.
Effect of Implantation Conditions on the Microstructure of High-Current, Oxygen Implanted Silicon-on-Insulator Material
Authors: Visitsemgtrakul S. , Cordts B.F. , Krause S. 
Published: March 2011

ABSTRACTConventional and high resolution electron microscopy were used to study structural development in silicon-on-insulator material produced by oxygen implantation at temperatures of 525 to 700°C, doses of 0.3 to 1.8 × 1018 cm-2, and current densities of 1 and 10 mA/cm2. Implantation temperature has the strongest effect on the microstructure and defect formation, both in as-implanted and annealed material. In the top silicon layer of as-implanted SIMOX, oxygen bubbles form near the surface when the wafer temperature is ≥ 550°C. A new type of defect, the multiply faulted defect (MFD), has been observed at the upper edge of the implantation region with a density of 108 cm-2 in the samples implanted at the temperature of ≥ 600°C. As dose increases from 0.3 to 1.8 × 1018 cm-2, the bubbles grow larger and the trails of bubbles lengthen while the character and density of MFDs remain the same. A continuous buried oxide layer forms at doses ≥ 1.5 × 1018 cm2. No significant difference in structure is observed when a current-density increases from 1 to 10 mA/cm2.
Mechanism of Ion-Induced Solid-Phase Crystallization and Amorphization
Authors: chaki T.k. 
Published: March 2011

ABSTRACTA mechanism is proposed to explain ion-induced solid-phase epitaxial growth (SPEG). It is argued that radiation-enhanced diffusion in amorphous solid is the cause of ion-induced SPEG at relatively low temperatures. The atoms in the amorphous solid near the crystalline/amorphous interface adjust their positions to lattice sites due to a free energy decrease associated with the transformation from amorphous to crystalline solid. An expression for the velocity of ion-induced SPEG is derived. At low temperatures and high irradiation dose rates, a large number of atoms in the lattice gets displaced and the free energy of the crystalline solid can increase to such a value that the crystalline/amorphous interface may remain stationary. It is shown that the dose rate at which the interface remains stationary increases with the temperature, following an Arrhenius dependence.
Adhesion Studies of Au Films on GaAs using Ion-Assisted Deposition Techniques
Authors: Kellock A.J. , Bardin T.T. , Wang P-W. , Baglin J.E.E. , Pronko J.G. 
Published: March 2011

ABSTRACTA series of experiments have been performed to examine the ability of ion beam assisted thermal deposition to produce good adhesion of Au metallization on GaAs <100> substrates. A study of the influence of Ar ion-assisted thermal deposition of the Au films as well as in situ pre-sputtering of the GaAs surface with low-energy Ar ions prior to thermal deposition, shows that strong adhesion can be achieved without resorting to chemical cleaning. The substrate temperature and the relative flux of Ar ions to incident Au atoms were varied in order to correlate these parameters with film adhesion. The interfaces of films processed under these various conditions were examined by XTEM, RBS and XPS. Orientation texture was studied by x-ray diffraction (XRD).
Ar+ Induced Interfacial Mixinc in the Pd/Cu Bilayer System
Authors: Kim H.K. , Song J.H. , Kim S.K. , Jeong K. , Whang C.N. , Smith R.J. 
Published: March 2011

ABSTRACTIon beam mixing of a Pd/Cu bilayer is studied using irradiation with 80 keV Ar+ ions at room temperature. RBS analysis shows that intermixing has occurred across the Pd/Cu interface, and that the mixing amount increases with increasing ion dose, which agrees well with a model for radiation enhanced diffusion. It is found that the Cu3Pd phase grows in a layer-by-layer manner.
Lead inclusions in aluminium
Authors: Johnson E. , Gråbaek L. , Bohr J. , Johansen A. , Sarholt-Kristensen L. , Andersen H.H. 
Published: March 2011

ABSTRACTIon implantation at room temperature of lead into aluminium leads to spontaneous phase separation and formation of lead precipitates growing topotactically with the matrix. Unlike the highly pressurised (∼ 1–5 GPa) solid inclusions formed after noble gas implantations, the pressure in the lead precipitates is found to be less than 0.12 GPa.Recently we have observed the intriguing result that the lead inclusions in aluminium exhibit both superheating and supercooling [1]. In this paper we review and elaborate on these results. Small implantation-induced lead precipitates embedded in an aluminium matrix were studied by X-ray diffraction. The (111) Bragg peak originating from the lead crystals was followed during several temperature cycles, from room temperature to 678 K. The melting temperature for bulk lead is 601 K. In the first heating cycle we found a superheating of the lead precipitates of 67 K before melting occurred. During subsequent cooling a supercooling of 21 K below the solidification point of bulk lead was observed. In the subsequent heating cycles this hysteresis at the melting transition was reproducible. The full width of the hysteresis loop slowly decreased to 62 K, while the mean size of the inclusions gradually increased from 14.5 nm to 27 nm. The phenomena of superheating and supercooling are thus most pronounced for the small crystallites. The persistence of the hysteresis loop over successive heating cycles demonstrate that its cause is intrinsic in nature, and it is believed that the superheating originates from the lack of free surfaces of the lead inclusions.
Charge States of Heavy Ions with Energy in the MeV Range in Crystalline Semiconductor Targets
Authors: Mazzone A.M. 
Published: March 2011

ABSTRACTIn this work a formalism for the evaluation of electronic losses of heavy ions with energy of few MeV in crystalline semiconductor targets is presented. The stopping values are used in a Monte Carlo simulation to calculate the ion range in silicon and in gallium arsenide for a random orientation of the target and under channelling conditions.
Internal Blackbody Emission Interferometry for Measurement of Crystallization Kinetics and Optical Properties of Amorphous Si and Ge
Authors: Roth J. A. , Olson G. L. 
Published: March 2011

ABSTRACTThe spectral emissivity of a semi-transparent thin film on a heated substrate varies with film thickness due to optical interference within the layer. This leads to oscillations in the emitted blackbody radiation intensity when the film thickness changes with time. We show how measurements of these oscillations have been used to determine the crystallization kinetics and optical constants of ion-implanted amorphous Si and Ge layers undergoing solid phase epitaxial crystallization. A comparision of emission and reflectivity data illustrates that the emission behavior can be understood in terms of a straightforward optical model.
Focused 0.5 MeV Ion Beam Line with Low Aberration Quadrupole Magnets
Authors: Inoue K. , Takai M. , Ishibashi K. , Kawata Y. , Suzuki N. , Namba S. 
Published: March 2011

ABSTRACTA microbeam line with precisely designed quadrupole magnets has been developed and installed at the Research Center for Extreme Materials, Osaka University. For the purpose of applying the beam line to microbeam RBS/channeling, the damage in <100>Si due to the irradiation of probe beams was studied as a function of incident ion dose from 1015 to 1018 /cm2 with a flux of 8 × 104 nA/cm2. It was found that the dose for channeling measurements should be less than several 1017 /cm2.