bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation of Powders and thin Films of Complex Oxides From
Metal Alkoxides
Authors: Yanovskaya M.I. , Kotova N.M. , Obvintseva I.E. , Turevskaya E.P. , Turova N.Ya. , Vorottlov K.A. , Lsolov'yova L. , Kovsman E.P. 
Published: April 2011

ABSTRACTPreparation of complex oxides in the form of powders and thin films from
metal alkoxides is discussed. Most attention is paid to ferroelectric and
related materials ‐ complex titanates and zirconates. Techniques for
preparation of high‐purity morphologically homogeneous powders
Ti2, ZrO2 barium titanate and
BaTiO3‐based solid solutions, MgTiO3,
Bi2WO6, Bi2MoO6 are proposed
and discussed wilh respect to their application in ceramics technology. The
solutions prepared electrochemically in methoxyethanol were widely used for
formation of thin films, e.g. Y2O3‐stabilized
ZrO2 and ρζγ solid solutions on Pt‐coated silicon
substrates.
Inorganic-Organic Hybrid Aerogels
Authors: Schubert Ulrich , Schwertfeger Fritz , Hüsing Nicola , Seyfried Elisabeth 
Published: April 2011

ABSTRACTOrganically modified silica aerogels were prepared by
NH4OH-catalyzed hydrolysis and condensation of
RSi(OMe)3 / Si(OMe)4 mixtures, followed by
supercritical drying of the alcogels with methanol or CO2.
Terminal alkyl or aryl groups, bridging groups or functional organic
(methacryloxypropyl or glycidoxypropyl) groups were employed for R. By the
proper choice of the organic groups, the RSi(OMe)3 /
Si(OMe)4 ratio and the drying conditions, hydrophobic
aerogels, being insensitive towards moisture, were obtained with no residual
Si-OH or Si-OMe groups left. The transparency and porosity of the
organically modified aerogels was only slightly diminished relative to
unmodified silica aerogels. The elastic constant of the aerogels was
significantly influenced by the kind of organic groups. By pyrolysis of the
phenyl-substituted aerogels, nanometer-sized carbon structures were
generated. They partly coat the primary aerogel particles and provide a very
high mass specific extinction in the wavelengths interval critical for
thermal radiative transport.
Synthesis of Hybrid Inorganic-Organic Sol-Gel Coatings for
Optics
Authors: Lebeau B. , Guermeur C. , Sanchez C. 
Published: April 2011

ABSTRACTThe synthesis of transparent hybrid organic-inorganic coatings obtained from
condensation between alkoxysilane containing grafted dyes (azo dyes or
phthalocyanines) and metal alkoxides precursors has been performed. The Red
17 azo dye, known for its high second order polarisability, was bonded to
the silicon oxide network following two procedures: a silylation reaction
between Red 17 and triethoxysilane; a coupling reaction between Red 17 and
3-isocyanatopropyltriethoxysilane. Silicon phthalocyanines (known for their
third order polarisability and inverse saturable absorption properties) were
incorporated into the silicon oxide network by a silylation reaction.
Phthalocyanine doped transparent hybrid organic-inorganic coatings were
obtained from condensation between diethoxymethylsilane and zirconium
propoxide precursors.
29Si NMR and XPS Investigation of the Structure of Silicon
Oxycarbide Glasses Derived from Polysiloxane Precursors
Authors: Corriu R.J.P. , Leclercq D. , Mutin P.H. , Vioux A. 
Published: April 2011

ABSTRACTTwo silicon oxycarbide glasses with different compositions (O/Si ratio 1.2
and 1.8) were prepared by pyrolysis at moderate temperature (900 °C) of
polysiloxane precursors. Their structure was investigated using quantitative
29Si solid-state NMR and X-ray photoelectron spectroscopy
(XPS). The environment of the silicon atoms in the oxycarbide phase
corresponded to a purely random distribution of Si-O and Si-C bonds
depending on the O/Si ratio of the glass only and not on the structure of
the precursors. At the light of the NMR results, the Si2p XPS spectra of the
glasses may be interpreted using the contribution of the five possible
SiOxC4-x tetrahedra. The Cls
spectra of these glasses indicated the presence of oxycarbide carbon in
CSi4 tetrahedra, similar to carbide
carbon, and graphitic-like excess carbon.
Influence of the nature of the R Group on the Hydrolysis and
Condensation Process of Trifunctional Silicon Alkoxides,
R-Si(OR')3
Authors: Delattre Laurent , Babonneau Florence 
Published: April 2011

ABSTRACTThe hydrolysis and condensation reactions of three trifunctional silicon
alkoxides, R-Si(OEt)3, with various R alkyl chains (R =
CH3, C2H5, C8H17),
was followed by 29Si and 1H Nuclear Magnetic
Resonance. The condensation reactions are faster for methyltriethoxysilane
and the degree of condensation of the system is higher. The other two
systems have similar behaviors during the first hours, with lowest degree of
condensation. The condensation reactions slow down for the
octyltriethoxysilane, due to the presence of the long alkyl chains which
prevent condensation reactions between oligomeric species. The influence of
the addition of tetraethoxysilane (TEOS) was studied: for all three systems,
the degree of condensation of the network is higher, indicating the role of
cross-linking played by TEOS.
Interactions Between Crystalline Si3N4 and
Preceramic Polymers at High Temperature
Authors: McGinn Joseph T. , Blum Yigal , Johnson Sylvia M. , Gusman Michael I. , McDermott Gregory A. 
Published: April 2011

ABSTRACTPolymeric precursors to Si3N4 were mixed with
Si3N4 powder, in various combinations, to form
coatings in Si3N4 and to control microstructure of
Si3N4. The microstructure of polymer-derived
ceramic and preceramic materials was examined by transmission electron
microscopy (TEM) after heat treatment at 900°C and 1200°C and sintering at
1650°C. The observed micro-structure suggests that the
polymer-derived-material properties will approach those of conventionally
formed Si3N4. With proper viscosity control, gaps
between α-Si3N4 powder particles as narrow as 5 to 10
nm are filled by the polymer-derived-material, ensuring full wetting of the
α-Si3N4. Voids as large as 0.3 μm between
(α-Si3N4 particles are filled by the ceramic
precursor, reducing the size of pores formed during subsequent sintering
processes. Intimate bonding between the amorphous, polymer-derived-material
and the crystalline Si3N4 grains is observed after
heat treatments or sintering, a necessary condition for achieving
high-quality properties similar to conventional material. Acicular grains of
α-Si3N4 formed from the equiaxed
β-Si3N4 powder/PCMS mixture upon sintering are also
observed.
The Influence of Morphological Aspects in the Reaction Pathway
and Superconductive Properties of Bi2223-Ca2CuO3
Ceramic Composites
Authors: Miao H. , Primo V. , Ibañez R. , Sapiña F. , Beltran A. , Beltran D. 
Published: April 2011

ABSTRACTA variation of the solid-state matrix technique has been developed as a
procedure for the preparation of 2223 bismuth superconducting phases
[(Bi,Pb)2Sr2Ca1-nCunO4+2n,
n=3]. The adequate processing of samples of nominal compositions 2223+x
0021, obtained both by this procedure and by the polymer matrix method, has
allowed the modification of the microstructure of the calcium copper excess,
with no noticeable change in that of the 2223 grains. The study of the phase
evolution in the processing of the samples has shown that the formation rate
of the 2223 phase is faster when the particle size of the calcium cuprate is
smaller. A dependence of the intergranular superconducting properties on the
secondary phase is observed, appearing as a maximum in
Jc0/μcer at x=0.2 and x=0.5 for samples prepared by
solid state matrix and polymer matrix methods, respectively.
Interphase Study By Xps of Sol-Gel ZrO2 Coatings On
Stainless Steel
Authors: Quinson Jean-Francois , Chino Chantal , De Becdelievre Anne-Marie , Guizard Christian 
Published: April 2011

ABSTRACTZrO2 coatings were obtained by the the alkoxide route and
deposited onto stainless steel using the dip coating technique. The starting
solutions were prepared by mixing zirconium tetrabutoxide, isopropanol,
acetylacetone. The water content for the hydrolitic reaction arose from the
atmosphere moisture.Useful information for the structural organization of the zirconia/steel
interphase is given by XPS analysis.It is found that during firing treatment, the main components (Fe, Cr, Ni)
of the stainless steel diffuse into the ceramic coating. XPS data allow to
describe the chemical composition variation from the bulk substrate to the
outer coating surface.
Thermal Stability Enhancement Of Rubbery
Ormosils
Authors: Kramer S. J. , Mackenzie J. D. 
Published: April 2011

ABSTRACTThermal stability of a novel rubbery ORMOSIL of condensed tetraethoxysilane
(TEOS) and polydimethylsiloxane (PDMS) was investigated along with methods
by which to improve this stability. Based upon literature review of siloxane
systems, modifications of the base ORMOSIL system was made which included
substitution of polydimethyldiphenylsiloxane (PDMDPS) for PDMS, adding
antioxidant, and adding iron compounds. Relative enhancement was
investigated in terms of resilience measurements, and was also analyzed with
thermo-gravimetric analysis (TGA) and differential thermal anaysis
(DTA).
Synthesis of (Alumino) Silicate Materials Using Organic
Molecules and Self-Assembled Organic Aggregates as Structure-Directing
Agents
Authors: Davis Mark E. , Chen Cong-Yan , Burkett Sandra L. , Lobo Raul F. 
Published: April 2011

ABSTRACTMicroporous zeolites can be synthesized using organic structure-directing
molecules whose function is to organize inorganic species into particular
topologies that then spontaneously self-assemble into the final crystalline
materials. Extension of the zeolite assembly process to the use of organic
molecular aggregates as structure-directing agents yields ordered mesoporous
materials like MCM–41 and MCM–48. A unifying picture of the assembly
processes ocurring in the syntheses of micro- and mesoporous materials is
presented.
29Si, 17O Liquid NMR and 29Si CP-MAS NMR
Characterization of Siloxane-Oxide Materials,
[(CH3)2SiO/TiO2,
(CH3)2SiO/ZrO2]
Authors: Babonneau Florence 
Published: April 2011

ABSTRACTSol-gel derived siloxane oxide materials are an entirely new family of
hybrid systems at the frontier between silicones and glasses or ceramics,
with a large variety of potential applications. Better control of the
chemistry involved in their preparation should lead to an improvement in
their properties, and this requires an investigation of the whole process,
from the solution to the final materials. Nuclear Magnetic Resonance is a
very suitable technique for this purpose, and this paper will give some
illustrations on model systems
(CH3)2SiO/TiO2,
(CH3)2SiO/ZrO2, prepared from
dimethyldiethoxysilane and titanium or zirconium alkoxides. It will be
focused mainly on the use of 170 solution NMR which clearly shows
the formation of Si-O-Ti or Si-O-Zr bonds, but also their disappearance
during the aging process. 29Si MAS-NMR spectra of dried gels
confirm that the difunctional units are mainly in polydimethylsiloxane
chains, and that the system is phase separated. However, the use of
cross-polarization techniques involving lK and 29Si
nuclei will allow the detection of small number of units in a more
constrained environment, certainly close to oxide-based particles.
Biochemical Processing of Materials: A Review
Authors: Hench Larry L. 
Published: April 2011

ABSTRACTMany biological systems have evolved means of controlling the architecture of inorganic-organic composites at a nanometer scale. The principles of biochemistry and materials science underlying the potential use of biochemical processing to develop new molecularly tailored materials are discussed, with emphasis on:methods of stereochemical control of the organic-inorganic interface,genetic and enzymic control of biosynthesis and biomineralization,molecular orbital modelling of bio organic-inorganic interfaces,barriers and limitations of biomimetic and hierarchical processing,examples of unique materials made with biochemical processing.needs and potential applications in human prostheses.
Theoretical and Experimental Investigations of Fullerene Derivatives: C60H2, C60H4, C70H2, AND C60(CH2)2
Authors: Jacobs S. Joshua , Gillen Kenneth T. , Cahill Paul A. , Henderson Craig C. , Rohlfing Celeste M. 
Published: April 2011

ABSTRACTHydroboration of C70 in toluene yields a 2:1 mixture of 1,9-C70H2 and 7,8-C70H2. Equilibration of these two isomers in the presence of a Pt catalyst reveals a free energy difference of 1.4 ± 0.2 kcal/mol. Whereas semiempirical calculations have been found to predict the energy ordering of many fullerene derivatives incorrectly, ab initio Hartree-Fock (HF) calculations have been found to yield quantitative predictions of experiment. The HF/6-31G* level energy separation of l,9-C70H2 and 7,8-C70H2 of 1.3 kcal/mol is in excellent agreement with experiment. Relative stabilities of isomers of bis(methano)fullerenes were found to parallel those of analogous C60H4 isomers. Density functional theory (DFT) methods have been tested and are equivalent in accuracy to HF methods if similar basis sets are used. C60H2 and C60H4 can be efficiently produced on larger (≥ 50 mg) scales with diimide generated from potassium azodicarboxylate and acetic acid in o-dichlorobenzene.
Structural and Electrical Characterization of Highly Tetrahedral-Coordinated Diamond-Like Carbon Films Grown by Pulsed-Laser Deposition
Authors: Siegal M. P. , Friedmann T. A. , Kurtz S. R. , Tallant D. R. , Simpson R. L. , Dominguez F. , McCarty K. F. 
Published: April 2011

ABSTRACTHighly tetrahedral-coordinated-amorphous-carbon (a-tC) films deposited by pulsed-laser deposition (PLD) on silicon substrates are studied. These films are grown at room-temperatures in a high-vacuum ambient. a-tC films grown in this manner have demonstrated stability to temperatures in excess of T = 1000°C, more than sufficient for any post-processing treatment or application. Film surfaces are optically smooth as determined both visually and by atomic-force microscopy. PLD growth parameters can be controlled to produce films with a range of sp2 - sp3 carbon-carbon bond ratios. Films with the highest yield of sp3 C-C bonds have high resistivity, with a dielectric permittivity constant s σ 4, measured capacitively at low frequencies (1 – 100 kHz). These a-tC films are p-type semiconductors as grown. Schottky barrier diode structures have been fabricated.
In-Situ Ellipsometric Monitoring of the Electron Cyclotron Resonance Etching of Diamond-Like Carbon
Authors: Ianno N.J. , Ahmer S. , Pittal S. , Woollam John A. 
Published: April 2011

ABSTRACTThe electron cyclotron resonance (ECR) etching of diamond-like carbon films in an oxygen plasma has been studied. The input variables were flow rate, pressure, power, and bias, while the output parameters were etch rate, and uniformity. In-situ ellipsometry, performed at 44 wavelengths simultaneously, was employed to monitor the etch process in real time. We will show that DLC films can be etched without an applied bias, but the application of an rf induced dc bias greatly enhances etch uniformity. Further, the etch rate is a strong function of the bandgap of the DLC film.
An Analysis of Densification Process of Carbon/Carbon Composites
Authors: Oh Seh-Min , Park Yang-Duk 
Published: April 2011

ABSTRACTAn analytical method was developed to calculate efficiency of densifying carbon/carbon (C/C) composite with pitch for each cycle. Three factors were defined in the densificationprocess: an impregnation efficiency, w, a retention efficiency, x, and an overall densification efficiency, E. The relationships developed were applied to the results for three cycles of densification of C/C composite to evaluate the factors which depend on the route of impregnation and carbonization. The impregnation efficiency increases as the process is repeated due to a decrease of porosity, and the retention efficiency shows a tendency to be in a reverse proportion to the impregnation efficiency. The overall densification efficiency depends on the carbonization yield of pitch impregnant. The carbonization route P+A+G is the most effective method in densifying C/C composites, in which pressure carbonization(P) increases the carbonization yield and the retention efficiency of pitch, and graphitization(G) increases the impregnation efficiency.
Properties of Ti1-xAlxN Deposited Using Dual Rotatable Magnetrons for Automotive Glass Privacy Coatings
Authors: Morley T. S. , Vyletel B. N. , Crawley R. L. , Nietering K. E. 
Published: April 2011

AbstractOptically thin films of Ti1-xAlxN were sputter deposited using dual rotatable cathodes in nitrogen and argon-nitrogen environments. The sputtering parameters and film properties were analyzed to develop predictive techniques for possible feedback control during deposition. Also, it was found that feedback control during deposition was suitable for controlling film composition in some magnet configurations.
Measurement of the Effect of Temperature on Stress Distribution and Deformation in Multilayer Optical Thin Film Structures
Authors: Madras Cynthia G. , Wong P. Y. , Miaoulis I. N. , Goldman L. M. 
Published: April 2011

AbstractThis study investigates methods of predicting the deformation and stress distribution in multilayer optical thin film structures. The thin film layers include materials of various thermal expansion coefficients, elastic moduli, and melting temperatures. Each layer is deposited at a different temperature, causing complex thermal and deposition stresses throughout the structure. In addition, since the deposition temperatures of some of the layers are high (>600°C), stress relaxation and plastic flow may occur in materials with low melting temperatures. A combination of theoretical predictions and experimental measurements is used to measure and quantify the deformation caused by residual and thermal stresses in the films as well as any plastic deformation that may have occurred. Results from a model using multilayer plate bending theory to determine the elastic deformation of the device due to thermal stresses are reported. These predictions, as well as a more common method of predicting film stress and curvature, are compared to experimentally measured curvature changes as a function of temperature in the samples. However, when plastic deformation begins to occur at high temperatures, the residual stress and degree of deformation are no longer predictable based on elastic theory alone, and have to be measured experimentally. Plastic deformation in the substrate is discussed as a cause of a high observed curvature following sample heating.
Electroplasticity and Electromigration
Authors: Baker Shefford P. , Knauss Michael P. , Möckl Ulrich E. , Arzt Eduard 
Published: April 2011

AbstractIt is known that an electric current can interact with dislocations in metals. Recent studies suggest that these interactions include current-induced dislocation motion and multiplication (electroplasticity) through both glide and climb mechanisms. Such interactions might be expected to effect both the mechanical properties and the electromigration behavior of the thin metal conductor lines used in integrated circuits. The mechanical properties would be directly modified through changes in dislocation density and mobility. Changes in microstructure and strength could affect electromigration lifetime and failure morphology. In order to investigate the effects of current-dislocation interactions, we conducted three sets of experiments in unpassivated aluminum conductor lines: First, a nanoindentation device was used to measure the mechanical properties of the lines during application of current densities up to 6 MA/cm2. Second, the mechanical properties of the lines were measured ex situ as a function of time in accelerated electromigration testing conditions. Third, the nanoindentation device was used to damage the lines at specific sites and damage morphology was examined during subsequent electromigration experiments by means of in situ scanning electron microscopy. To date we observe no direct effect of electric current on the mechanical properties of conductor lines and no clear correlation between mechanical damage and electromigration failure characteristics. Based on theoretical calculations and previous experiments on bulk samples, these results were not expected.
Strained Layer Epitaxy: A Microscopic Description of Stress Driven Surface Diffusion
Authors: Lefebvre I. , Priester C. , Allan G. , Lannoo M. 
Published: April 2011

AbstractThe origin of the crosshatched morphology very often observed, for instance in the case of InGaAs on GaAs, is studied theoretically. The calculations are performed on the basis of a microscopic valence force field model.The force on an adatom induced by a periodic array of widely spaced dislocations is first determined. This is found to be attractive, in agreement with a previous classical elasticity description. Total energies of ridges are then calculated showing increased stability due to the misfit dislocations. The importance of the surface tension for the shape of the ridges is discussed. The results are finally compared to experimental evidence.
Relationship Between Stress and Surface Roughness in Krypton Implanted MgO
Authors: Gea Laurence , Loubet Jean-Luc , Brenier Roger , Thevenard Paul 
Published: April 2011

Abstract(001) MgO single crystals were implanted with 150 keV krypton ions (Kr+) at a fluence of 5.1016 ions.cm-2 . The implanted surface, observed with an Atomic Force Microscope (AFM) exhibits striking features that can be described as undulations with a wavelength of 0.5 [μm. We correlate these features to the decrease in density and the stresses induced by the implantation damage. As a matter of fact, a model of surface instabilities provides a relationship between the wavelength of the ondulations and internal stresses. Using this model, implantation stresses are calculated to 2.2 GPa. This is in good agreement with the value of 2 GPa obtained with the help of the microindentation technique and the literature data. Some effects of an ionizing post-irradiation on stress and surface roughness are described.
Cracking During Nanoindentation and its Use in the Measurement of Fracture Toughness
Authors: Harding D. S. , Oliver W. C. , Pharr G. M. 
Published: April 2011

AbstractResults of an investigation aimed at developing a technique by which the fracture toughness of a thin film or small volume can be determined in nanoindentation experiments are reported. The method is based on the radial cracking which occurs when brittle materials are deformed by a sharp indenter such as a Vickers or Berkovich diamond. In microindentation experiments, the lengths of radial cracks have been found to correlate reasonably well with fracture toughness, and a simple semi-empirical method has been developed to compute the toughness from the crack lengths. However, a problem is encountered in extending this method into the nanoindentation regime with the standard Berkovich indenter in that there are well defined loads, called cracking thresholds, below which indentation cracking does not occur in most brittle materials. We have recently found that the problems imposed by the cracking threshold can be largely overcome by using an indenter with the geometry of the corner of a cube. For the cube-corner indenter, cracking thresholds in most brittle materials are as small as 1 mN (∼ 0.1 grams). In addition, the simple, well-developed relationship between toughness and crack length used for the Vickers indenter in the microindentation regime can be used for the cube-corner indenter in the nanoindentation regime provided a different empirical constant is used.
Ultra-Thin Carbon Coatings for Head-Disk Interface Tribology
Authors: Glosli J. N. , Belak J. , Philpott M. R. 
Published: April 2011

AbstractMolecular dynamics computer simulations of the growth processes and microstructural properties of amorphous carbon (a:C) and amorphous hydrogenated carbon (a:CH) ultra-thin films have been performed. Films 1 to 10 nm thick were grown on a diamond (100) surface using Brenner’s[1–2] bond-order potential for hydrocarbons. The stoichiometry, radial distribution function, chemical bonding (amount of sp2 and sp3 hybridization) and residual stress are presented.