bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of Molecular Precursors of Group iv Metal Oxides by
Tga-Ftir Coupling
Authors: Poncelet Olivier , Guilment Jean , Truchet Sylvie 
Published: April 2011

ABSTRACTHalogenoalkoxides are promising molecular precursors useable in sol-gel
technology. They exhibit a lower sensitivity towards hydrolysis than common
alkoxides and so appear to be easier to handle. Some data about the
structure of titanium chloroalkoxides, pure and with the addition of a
controlled amount of water, were obtained using FT-Raman, while the effect
of thermal treatment under nitrogen or oxygen was studied using TGA-IR
coupling. Finally the oxide products were characterized by Raman and by
ED-XRMA, proving mat chloroalkoxides could be used as molecular precursors
of oxide by sol-gel process. We showed that TGA-FTIR coupling is a powerful
tool in order to study a thermal treatment and could be used to optimize
it.
Glass-Ceramics In The Systems La-Pb-Mn-B-O And
La-Pb-Mn-Te-O
Authors: Gattef E. , Staneva A. , Dimitriev Y. 
Published: April 2011

ABSTRACTCompositions from the systems Pb-Mn-B-O and Pb-Mn-Te-0 are used to
synthesize glass-ceramics obtained by solid state reactions and from
supercooled melts. By casting on a metal plate or by quenching with the aid
of twin rollers the melts are cooling. The glass-crystalline materials are
obtained after heating glasses from the combination of
PbO-MnO-B203 and PbO-MnO-TeO2 with the
addition of La203 from 10 to 50 wt.% and the formation
of the crystalline phases is determined.
Soft Hydrothermal Synthesis of New Microporous Materials Based
on Phosphate-Like Species
Authors: Beltran D. , Marcos M. D. , Amoros P. , Roca M. , Beltran A. 
Published: April 2011

ABSTRACTFactors controlling hydrothermal synthetic procedures are not well
understood. A good knowledge of the solution chemistry of precursor species
is the best reference for the design of rational procedures. Examples of the
predictive character of simple models in order to rationalize complex
syntheses are discussed in detail.
Preparation of Centimeter-Sized Zeolite Crystals by Hydrothermal
Seeded Growth
Authors: Klemperer Walter G. , Marquart Todd A. 
Published: April 2011

ABSTRACTCentimeter-sized crystals of pyridine dodecasil 3C (all silica zeolite
ZSM-39) have been prepared using hydrothermal seeded growth techniques and
characterized by differential scanning calorimetry, nuclear magnetic
resonance, optical microscopy and powder X-ray diffraction.
Dsc Study in Situ on Copolymerization of C60with Paracyclophane
Authors: Huang Shaoming , Yu Xuhai , Yang Changzheng 
Published: April 2011

ABSTRACTCopolymerization of C60with paracyclophane at high temperature was investigated by DSC in situ. Situ DSC profiles of mixed solids with different mole ratio of C60/paracyclophane(2:1, 1:1; 1:2; 1:4; 1:10) were determined. Experimental results show that C60first dissolves in melting paracyclophane (280-330°C) then reacts with paracyclophane at 400-520°C. Copolymerization reaction is a stepwise and continued process. The reaction does not take place when the temperature is lower than 400 °C. The ratio of C60/paracyclophane affects the copolymerization process which is the reaction of C60with p-xylylenediradical and also affects the structure of the resulting product. Semi-quantitative analysis of DSC profiles indicates every C60molecule reacts with about 4-5 paracyclophane molecules to form crosslinking elastic copolymer. The structure of the copolymer may be like starburst dendrimer polymer. The copolymer was also characterized by IR, UV-VIS, and ESR.
Electronic Properties of C58Bn Fullerenes
Authors: Esfarjani Keivan , Gu Bing-Lin , Maruyama Yutaka , Ohno Kaoru , Kawazoe Yoshiyuki 
Published: April 2011

ABSTRACTRecent studies of electronic structure of solid fullerenes have revealed many interesting properties of these systems. In the present paper, the effects of substitution of carbon atoms by nitrogen and/or boron. We have modified our C60 fcc band-structure program to calculate the electronic properties of the C58BN fcc crystal, where we adopt the mixed-basis approach in which the Is, 2s, and 2p orbitals in addition to about 2000 plane waves are included. The band structure and the charge density distribution are calculated for the first time. When B and N are substituted in places of two C atoms sharing a double bond in C60, we found that there is no donor nor accepter level, and no net charge transfer between B and N. This character is considerably different from the boron-substituted fullerenes.
Growth Phenomena of Carbon Nanotubes Produced by Arc-Discharge
Authors: Zhou Dan , Seraphin Supapan , Wang Su 
Published: April 2011

ABSTRACTBased on the high resolution TEM observations, we report here on the nonconcentric growth phenomena of carbon nanotubes from the arc-discharge. We also report on a novel form of carbon nanoclusters - the strings of carbon nanobeads - produced by the catalytic arc-discharge with Ni as the catalyst, and on the bundles of single-walled carbon nanotubes, synthesized with YC2 as the catalyst, growing radially out from YC2 particles.
Photoluminescence by Hydrogenated Carbon Solids in Interstellar Space
Authors: Witt Adolf N. 
Published: April 2011

ABSTRACTWe review the observational evidence for the widespread existence of hydrogenated carbon dust in astronomical environments. Photoluminescence by such materials appears strongly enhanced in regions where additional hydrogenation becomes possible, e.g. through the photodissociation of abundant molecular hydrogen. Recent laboratory experiments have demonstrated that rehydrogenation of previously annealed hydrogenated amorphous carbon (HAC) does indeed restore the photoluminescence, and furthermore, hydrogenation of pure amorphous carbon leads to characteristic HAC photoluminescence, which can be further enhanced by UV irradiation. Present evidence suggests that hydrogenated amorphous carbon may represent a significant fraction of the interstellar dust mass in the Milky Way Galaxy.
Special C44 Isomers
Authors: White C.T. , Lyons M. , Brenner D.W. , Mintmire J.W. , Robertson D.H. , Mowrey R.C. , Dunlap B.I. 
Published: April 2011

ABSTRACTO'Keefe, Ross, and Baronavski, using laser vaporization of graphite and time-of-flight mass spectrometric detection have observed enhanced abundances of C+N cluster ions not only for n=50 and 60 but also for N = 44. Stimulated by this experimental result we have carried out a search for unusually stable C44 fullerene isomers. In this search, all possible 87 fullerene isomers of C44 were first generated and then classified according to the number of bonds, p, shared by abutting pentagons. We found that for C44 the minimum value of p is 8 and that there are only two C44 fullerenes with this value of p. Self-consistent geometry optimized calculations at the AM1 level show that these two special C44 fullerene isomers—although differing from one another by only about 0.1 eV in total energy—are over 1.0 eV more stable than any of the other possible 85 fullerene isomers of C44. These self-consistent-field calculations not only single out these two C44 fullerenes for special attention, but also further confirm the instability of abutting pentagons for lower fullerenes (those fullerenes with less than 60 carbon atoms).
A Photoluminescence Detected Magnetic Resonance (PLDMR) Study of C70 Films, Glasses and Photopolymerized and Oxidized Fullerenes
Authors: Lane P. A. , Shinar J. 
Published: April 2011

ABSTRACTThe X-band PLDMR of C70 films and C70 molecules isolated in a toluene/polystyrene glass matrix (C70:T/PS) is described. The PLDMR of C70:T/PS strikingly differs from that observed in C60:T/PS due to much longer triplet lifetimes. The PLDMR of C70 films indicates that the delocalized triplet is distorted by intermolecular interactions and shows a half-field resonance due to triplet-triplet fusion. In addition, a broader powder pattern and a narrow enhancing line at g=2.0029 are observed. The former is attributed to a localized triplet exciton of size similar to a 5- or 6-membered ring. The latter is believed to result from enhanced polaron recombination. The PLDMR of oxidized and photopolymerized films quenches the localized triplet and reveals the possibility of an even more delocalized exciton.
Synthesis, Characterization and Properties of Ionic Metal—Fullerene Adducts
Authors: Huang Shaoming , Yang Changzheng , Yu Xuehai 
Published: April 2011

ABSTRACTIonic metal-fullerene adducts C60M ( M = Li+, Mg2+, Ca2+, Sr2+, Ba2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, A13+ Ag+, Ce3+ ) are synthesized by reaction of watersoluble C60Lin with metal salt. 13C NMR of C60Li in D20 gives a sharp peak at 171.44 ppm which is much higher than the chemical shift of C60 in benzene ( 142.98 ppm ). Elemental analysis suggests the state of C60 in the adducts is C605-. ESR spectra of the adducts show a strong narrow peak at 9=2.001. UV-Vis and IR spectra of those adducts are completely different from those of C60. Magnetic measurement indicates that C60Li, C60Ce are antiferromagnetism and C60Fe adducts is ferromagnetism in the range of 150–300 K. But C60Fe adduct becomes paramagnetism when temperature is lower than 150 K. Mossbauer spectroscopy indicates Fe3+ in C60Fe adduct is Fe3+ (I.S.=0.30 mm/s, Q.S.=0.67 mm/s). The experimental results strongly suggest that C605- is a stable single free radical polyanion of fullerene which is a weak acid radical and possesses the similar properties with general inorganic anion. This is the first report on the synthesis and properties of air-stable and water-soluble polyanion of fullerene( C605-). A method for preparing metal-fullerene adducts has been developed, and many unusual properties of the adducts are found.
Nucleation Enhancement and Growth Of Diamond Films Using An Enclosed Combustion Flame
Authors: Morrison P. W. , Somashekhar A. , Glass J. T. , Prater J. T. 
Published: April 2011

ABSTRACTThis research investigates the growth of diamond thin films using an enclosed oxyacetylene torch. Using statistical experimental design, we have systematically explored the parameter space to construct maps of nucleation density, film quality, and growth rate as functions of growth conditions. The deposition process is divided into nucleation enhancement and growth, and each step is optimized separately. In the study of the nucleation enhancement, we vary R = O2/C2H2, substrate-flame distance (z), and pretreatment time and determine the nucleation density and nucleation uniformity using electron microscopy. For the growth study, the variables are R, z, and substrate temperature, and we employ two different Raman scattering measurements to assess film quality. In one case, we determine a quality ratio β = diamond peak/(diamond peak + nondiamond peak); the second indicator is the luminescence determined from the baseline of the spectrum. In the growth study, the best film quality is comparable to the best films grown in an atmospheric flame in which R is cycled. We also find that the growth rate is a factor of 10 less than in the atmospheric flame.
Relationship Between Crystal Structure, Internal Stress and Properties in the Naturally Occurring Supportless Thin Films of Chrysotile Asbestos
Authors: Denes Georges , Le Van Mao R. , Vaillancourt A. 
Published: April 2011

AbstractChrysotile asbestos (empirical formula: Mg3Si2O7.2H2O, structural formula: Mg3Si2O5(OH)4) crystallizes in a sheet structure so thin that it is equivalent to a thin film that has no support. The magnesium ions are too large to fit comfortably in their octahedral sites, the size of which is determined by the network of SiO4 tetrahedra. The squeezing of the magnesium ions in sites that are too tight forces the thin layers to bend and coil around themselves. The bending of the unit-cells results in the presence of an enormous amount of highly directional stress, which has been analyzed by X-ray diffraction. The carcinogenic properties of chrysotile asbestos are a direct consequence of this stress.
Dependence of Stress on Background Pressure in Sputtered Mo/Si Multilayer Films
Authors: Windt David L. , Brown W. L. , Volkert C. A. , Waskiewicz W. K. 
Published: April 2011

AbstractWe have measured the stress in Mo/Si multilayer films deposited by magnetron sputtering, using the wafer-curvature technique, and find a strong dependence on background pressure. For multilayers containing 40 bilayers of ˜4.3 nm Si layers and ˜2.6 nm Mo layers, the stress increases from approximately −280 MPa (compressive) to −450 MPa as the background pressure in the deposition chamber (i.e., measured just prior to deposition) decreases from 1.0 } 10−5 to 6.0 } 10−8 torr. For multilayers of the same period but with thicker Mo layers, the dependence on background pressure is even stronger. X-ray (λ = 0.154 nm) diffraction measurements reveal a slight increase in interfacial roughness for films deposited at high background pressure. Atomic concentrations of incorporated oxygen and carbon, measured with Auger electron spectroscopy, were found to be less than ˜0.5 at.% for all samples. However, the average hydrogen concentration, as determined from forward-recoil-scattering measurements, was found to vary from ˜0.3 at.% to ˜1.6 at.%, increasing with both background pressure and Mo layer thickness. We discuss possible mechanisms for the observed dependence of film stress on background pressure, including gas incorporation and the affect of residual gas atoms on adatom mobility.
Mechanical Properties of Alumina Films Sputtered Over Steps
Authors: Ross C. A. , Barrese J. J. 
Published: April 2011

AbstractThe properties of sputtered films are strongly affected by the topography of the underlying substrate, due to the dependence of film growth and resputtering yield on the angle of incidence of the sputtered material and other species from the plasma. Thick r.f.-sputtered alumina films were deposited with different levels of substrate bias onto substrates into which parallel grooves had been cut. The alumina sputtered in the vicinity of the grooves forms well-defined regions with a lower incorporated argon content than the alumina sputtered onto the planar parts of the substrate. The ratio of compressive stress perpendicular to the grooves compared to the stress parallel to the grooves varies from 0.85 at zero substrate bias and 0.5 at biases of -50V and -100V. Comparing with finite element simulations, these ratios suggest that in the biased samples, the material near the steps has a lower level of compressive intrinsic stress than exists in the planar material. Nanoindentation was used to measure the modulus and hardness of the material near the steps and on the planar areas of the substrate. The alumina has an indentation modulus of 150 – 200 GPa and a hardness of 8 – 10 GPa, depending on its proximity to the grooves and on the substrate bias.
Mechanical Properties of Sputter-Deposited Nb5Si3 Film and Nb5Si3/Nb Microlaminates
Authors: Rawal S. P. , Swanson G. M. , Moshier W. C. , Misra M. S. 
Published: April 2011

AbstractMonolithic Nb5Si3 films and microlaminates consisting of alternating, equally thick layers of Nb and Nb5Si3 were synthesized by magnetron sputtering. Thick monolithic Nb5Si3 films (25,000 nm) were deposited on a sapphire substrate to set process parameters and evaluate the microstructure and mechanical properties of as-deposited crystalline films. Nb5Si3/Nb micro-laminates with modulation wavelengths (i.e., bilayer thickness) of 40 and 200 nm were deposited on Nb substrates. Mechanical properties (elastic modulus, microhardness, compressive yield strength) of the films and microlaminates were studied using the nanoindentation method and Vickers microhardness. Mechanical property test results are presented.
AFM/SEM Study of Thermally Induced Hillock Coalescence
Authors: Chaiken J. , Goodisman Jerry , Villarica R. M. , Beasock J. V. , Walsh L. H. 
Published: April 2011

AbstractThe growth of hillocks and voids in metal films was studied. The applicability of a model involving fractals and kinetic equations was examined on the basis of whether there is independent justification for using scaling arguments in the model and whether there is reason to connect the evolution of hillocks with that of voids. Hillocks and voids were found to be self-similar across about three orders of magnitude of variation in spatial scale with the same fractal dimension. Voids and hillocks were found to have the same fractal dimension whether studied using atomic force microscopy (AFM) or scanning electron microscopy (SEM). The parameters obtained from these fractal analyses demonstrate quantitative internal consistency with an earlier time dependent study of thermal annealing effects on hillock distributions. Remarkably, area-perimeter data obtained from either a long-time study of a single void or a spatial average of a large number of different voids both yield quantitatively identical results.
Stress Evolution Kinetics in Ultra Thin Sputtered Au Films
Authors: Su Quanmin , Bailly Cecile , Wuttig Manfred , Corcoran Sean , Sieradzki Karl 
Published: April 2011

AbstractThe stress and microstructure of a thin film evolve in time if the deposition is interrupted or terminated. To establish the parameters which control the kinetics of both processes, ultra thin Au layers were sputter deposited on Si membranes and the stress evolution was monitored by a vibrating membrane technique. The evolution of the surface morphology was studied by scanning tunnelling microscopy. Aging after the termination of each deposition causes stress evolution towards higher tension which, around ambient temperature, follows an exponential law with a characteristic relaxation time of the order of tenths of seconds. This time was found to depend strongly on the accumulated film thickness as well as the surface morphology. The intrinsic stress of the depositing layer increases with the coverage of the film on the substrate. Scanning Tunnelling Microscopy shows that the film grows in a Volmer-Weber mode and that the average stress reaches a sharp maximum as the film become continuous.
Elastic Modulus and Hardness as Derived from Nanoindentation of Ni And Mo Films Prepared by Ion Beam Assisted Deposition
Authors: Wroblewski A. , Chechenin N. , BØttiger J. , Chevallier J. , Karpe N. , Krog J. P. 
Published: April 2011

AbstractUsing ion beam assisted deposition, 1.5–2.2 μm thick molybdenum and nickel films were prepared on silicon substrates. Some films were found to be strongly textured. By changing the rate of Ar+ bombardment during the deposition, the resulting in-plane film stresses could be changed from being strongly tensile to strongly compressive. Using nanoindentation, the hardness and elastic modulus were measured for all films, but no major influence of the film stress or different textures could be found. The elastic modulus of the Ni films was found to be close to its polycrystalline bulk value, and that of Mo was found to be about 70% of its polycrystalline bulk value.
Dielectric Fracture Leading to Metallic Connections by Laser Heating
Authors: Bernstein J. B. 
Published: April 2011

AbstractLaser programmed connections between adjacent lines on the same level of metallization have been developed as a means to achieve high density linking for customization in programmable gate arrays and for additive redundancy in restructurable integrated circuits. The resistances of the connections were approximately 1Ω and the overlaying passivation remained in tact. Links were formed by focusing a pulsed laser between two adjacent lines of metal, one of which was connected to a lower level of metal through a contact via. The mechanism of link formation appears to be a fissure contained within planarized passivation due to the stress of thermal expansion of the metallization with molten aluminum filling the crack.
Practical and Fundamental Studies of Nanocrystalline Composite Thin Films
Authors: Cheng Yang-Tse , Qiu Boqin , Tung Simon , Blanchard J. P. , Drew G. 
Published: April 2011

AbstractNanocrytslline composite films of Ag-Mo and Ag-Ni have been made by a co-deposition technique in UHV. The structure and composition have been studied by x-ray diffraction (XRD), transmission electron microscopy (TEM), and electron probe microanalysis (EPMA). For practical applications, the friction coefficient and wear rate were measured using a pin-on-plate machine for Ag-Mo composites deposited on steel. For fundamental studies, the hardness of the Ag-Ni composites deposited on oxidized Si wafers was measured using a nanoindenter. Experiments show that (1) reduction of friction and wear rate can be achieved using these nanocomposite coatings and (2) the hardness of the nanocomposites depends on the grain size. As the grain size of the Ag decreases from 100 to 10 nm, the hardness increases about 4 times.
Magnetostrictive Motor Development
Authors: Teter Joseph P. , Miesner John E. 
Published: April 2011

AbstractThis paper reviews the history and present state of magnetostrictive devices capable of controlled motion over large linear distances. Magnetostriction imparts the most force perunit weight of any technology however, the successful development of practical devices requires a multi-disciplinary effort involving materials science, magnetics, innovative mechanical design, electrical power engineering, and system control engineering. Advances todate have included demonstrations linear motors capable of 115 Newtons of force at 2.54 centimeters/second.
Low Temperature Magnetic Behavior of Ni-Fe-Al-B Shape Memory Alloys: Magnetic Susceptibility and Mössbauer Spectra.
Authors: Marquina V. , JimÉnez M. , Marquina M.L. , Ridaura R. , Aburto S. , GÓmez R. , Escudero R. , Morales F. , RÍos-Jara D. 
Published: April 2011

AbstractMagnetic susceptibility measurements and Mössbauer spectra (MS) were performed on a series of NixFeyAlzB shape memory ribbons obtained by a melt spinning technique. The MS at room temperature show quadrupole splittings of two iron sites. At low temperatures (T<120 K) relaxed magnetic spectra begin to develop and, in one of the samples, a complete resolved magnetic spectrum at 13 K was observed. The overall magnetic susceptibility curves show non Curie-Weiss type behavior with peaks at around 60 K and 35 K. These curves also show magnetic hysteresis in the up-down temperature cycle used during the measurements. We relate our observations with a structural change occurring at temperatures between room temperature and 260 K, a second one around 200 K, and with the developing of spin-glass behavior at low temperatures, when the magnetic influences of Fe and Ni atoms almost compensate each other.
Deformation of Adaptive Heterophase Crystal
Authors: Roytburd Alexander L. , Slutsker Julia 
Published: April 2011

AbstractA crystal which can be in two possible phase states is considered. During tensile extension the crystal is deformed elastically. After a certain amount of elastic strain a phase transformation begins. For each fixed level of strain an equilibrium mesostructure is established, which corresponds to a minimum in the free energy of the crystal. The equilibrium mesostructure consists of plane, parallel layers of a product phase separated by layers of an initial phase. The product phase itself consists of two or more different domains (twins) forming plane, parallel alternations. The volume fractions of the phases and of different twin components in the product phase are functions of strain and temperature. Above a critical temperature the product phase is a single domain (untwinned). The stress-strain curve which reflects the evolution of the equilibrium mesostructure is calculated. For deformation under a strain control the calculated equilibrium stress-strain curve has a section with negative slope that corresponds to a negative Young's modulus. If deformation proceeds under stress control, hysteretic stress-strain curves on loading and unloading will result from a section with negative slope.