bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation of Ti-Based Ferroelectric Thin Films from Heterometallic Coordination Compounds
Authors: Moshnyaga V. T. , Khoroshun I. V. , Petrenko P. A. , Shaban D. G. , Kuliuk L. L. 
Published: April 2011

ABSTRACTNovel binary (Pb, Ti) coordination compound were synthesized and used as precursor for the preparation of PbTiO3 films by means of aerosol deposition and spin coating. Single-phased textured thin films of perovskite structure were fabricated on MgO(100) substrate at T=380°C.
Chemical Etching of Diamond Revisited: Past Basic Research as Guide to New Processing Technologies
Authors: Cherian K. A. , Litster J. , Rudolph V. , White E. T. 
Published: April 2011

ABSTRACTIncreased rate of material removal and a high degree of surface finish during the polishing of diamond is desirable not only in the technology of gem diamond processing, but also for the tribological, optical, electronic and thermal management applications of chemical vapor deposited (CVD) diamond films. Conventional mechanical abrasion techniques, though with comparatively larger material removal rates, have limitations to the surface finish attainable due to the inherent nature of the material removal process - predominantly micro-chipping. Chemical etching of diamond, on the other hand is understood to involve atom by atom material removal preferentially from defect sites, but with lower overall material removal rates. It has been realized that a combination of these two processes, leading to chemi-mechanical polishing, may therefore provide better overall results, in terms of material removal and surface finish.In recent work on chemi-mechanical polishing of diamond, KNO3 - an oxidizing agent shown to be a dislocation etchant for diamond by Tolansky and Patel in the 1950s - has been employed. Dislocation etchants usually lead to the formation of block patterns on diamond surfaces under the usual etching conditions because of the normal and tangential etch rates (Vn and Vt) of comparable magnitude. KNO3 therefore would impose a limitation on the degree of surface finish attainable when used for chemi-mechanical polishing. However, if a chemical etchant and conditions for which Vn ≪ Vt could be established for diamond surfaces, better chemical polishing effects may be achieved. Experimental investigations in this direction have provided encouraging results and some aspects of the new results are presented.
Composite Films of Nickel / Silicon Carbide
Authors: Hepel Maria 
Published: April 2011

ABSTRACTThe electrodeposition of nickel/silicon carbide (Ni/SiC) composite films formed from modified Watt's bath solutions under potentiostatic conditions on steel substrates was investigated. The effects of deposition potential, pH, variable concentration of SiC in suspension, and additives, such as coumarin and EDTA, on the nickel nucleation and growth transients, as well as on the composition and morphology of Ni/SiC films are described. Improved Vickers microhardness and corrosion resistance of these composite films were found in comparison to those of particle-free deposits.
Precursors for the Chemical Vator Deposition of Titanium Nitride and Titanium Aluminum Nitride Films
Authors: Winter Charles H. , McKarns Peggy J. , Scheper Joseph T. 
Published: April 2011

ABSTRACTTitanium nitride and ternary alloys thereof are of significant interest due to their hardness, chemical resistance, and good electrical conductivity. We report the synthesis, structure, and properties of several new precursors to titanium nitride that are based upon hydrazine-derived ligands. Application of these complexes in titanium nitride film depositions is overviewed. Film properties and characterization are presented. We also describe a new process for the preparation of titanium aluminum nitride films, and focus on how the presence of small amounts of aluminum change the properties of the material.
Dispersed Complex Phosphates as Tailored Acid Catalysts: Synthesis and Properties
Authors: Sadykov Vladislav A. , Kochubei D. I. , Degtyarev S. P. , Paukshtis E. A. , Burgina E. B. , Pavlova S. N. , Maximovskaya R. I. , Litvak G. S. , Zaikovskii V. I. , Tsybulya S. V. , Tretyakov V. F. , Agrawal D. , Roy R. 
Published: April 2011

ABSTRACTThe relationship between the chemical composition, bulk real structure, surface properties and catalytic activity of dispersed complex framework zirconium phosphates with a NASICON-type structure is considered. For both crystalline and amorphous samples, a model of their bulk structure is suggested. The Lewis and Bröensted acidity was shown to vary broadly and be dependent upon the composition and preparation procedure, which is important for catalysts of hydro-carbons activation. Selective catalytic reduction of NOxby methane in excess oxygen appears to be one of the application areas for these systems.
Mocvd Palladium and Platinum Supported on Alumina Catalysts: Preparation and Characterization
Authors: Lopez Z. K. , Vargas J. R. , Valenzuela M. A. , Acosta D. R. 
Published: April 2011

ABSTRACTAn horizontal hot-wall MOCVD reactor was used to prepare palladium and platinum catalysts supported on alumina. A conventional impregnated Pt on alumina catalyst was prepared as comparison. The solids were characterized by XRD, Auger spectroscopy, HREM and H2-TPR. The operation conditions of the MOCVD reactor were fixed preparing several Pd catalysts until to find the appropriate deposition zone. The particle size of Pt catalysts prepared by MOCVD was at about 7 nm compared with 6 ran obtained with the Pt impregnated catalyst, measured by XRD. The HREM image of the Pt MOCVD catalyst showed a narrower particle size ranging from 1 to 4 nm. After calcination three Pt compounds were detected by TPR, which were attributed to PtO, PtO2and Pt-Al2O3interaction in MOCVD preparation. Additionally, a clear reduction of surface oxygens of alumina was also observed.
Chemical Control of Noble Metal Catalysis by Main Group Elements
Authors: Asakura K. , Okumura K. , Inoue T. , Kubota T. , Chun W-J. , Iwasawa Y. 
Published: April 2011

ABSTRACTThe catalytic interaction of noble metal and main group elements in Rh/one-atomic layer GeO2/SiO2and Pt/SbOxwas investigated. The high temperature reduction produced RhGe and PtSb bimetallic particles in which Pt and Rh were electronically modified to retard catalytic activity. However, unique selective catalyses of Rh/one-atomic layer GeO2/SiO2for CO hydrogenation reaction to oxygenate compounds and for NO+CO reaction to N2were found. Under the low temperature reduction of Rh/one-atomic layer GeO2/SiO2and the high temperature calcination of Pt/SbOx, the oxide phases, GeO2and SbOx, were stable and the selective reduction of ethylacetate to ethanol and the selective oxidation of iso-C4H10to methacrolein were observed. The high selectivities were ascribed to synergistic interaction between the noble metals and the main group element oxides through the diffusion of adsorbed species and reaction intermediates. The possibility of chemical control of noble metal-catalyses by main group elements is discussed.
Tem and Eels Investigation of a-C and ta-C Coated Field Emitters
Authors: Myers A. F. , Steel E. B. , Dingt M. Q. , Camphausen S. M. , Choi W. B. , Cuomo J. J. , Hren J. J. 
Published: April 2011

ABSTRACTThe microstructure of highly sp2 bonded amorphous carbon and partially tetrahedrally bonded amorphous carbon deposited on needle-shaped molybdenum field emitters by pulsed laser ablation and cathodic arc deposition techniques was studied using transmission electron microscopy and electron energy loss spectroscopy. Undoped and nitrogen-doped films were included in this study. The undoped laser ablation films were approximately 50% sp2 at the emitter tip and 65% sp2 along the shank, while the N-doped laser ablation films were highly sp2 bonded both at the tip and along the shank. These laser ablation films were continuous and relatively uniform, exhibiting an isotropie microstructure at the emitter tip and a columnar microstructure along the shank. The cathodic arc deposited films were predominantly sp2 bonded both at the tip and along the shank; these films were non-uniform, with an isotropie microstructure at the tip and regions of isotropie, columnar, and mixed microstructure appearing along the shank.
The Electronic Transport Mechanism in Amorphous Tetrahedrally-Coordinated Carbon Films
Authors: Sullivan J. P. , Friedmann T. A. , Dunn R. G. , Stechel E. B. , Schultz P. A. , Siegal M. P. , Missert N. 
Published: April 2011

ABSTRACTThe electronic transport mechanism in tetrahedrally-coordinated amorphous carbon was investigated using measurements of stress relaxation, thermal evolution of electrical conductivity, and temperature-dependent conductivity measurements. Stress relaxation measurements were used to determine the change in 3-fold coordinated carbon concentration, and the electrical conductivity was correlated to this change. It was found that the conductivity was exponentially proportional to the change in 3-fold concentration, indicating a tunneling or hopping transport mechanism. It was also found that the activation energy for transport decreased with increasing anneal temperature. The decrease in activation energy was responsible for the observed increase in electrical conductivity. A model is described wherein the transport in this material is described by thermally activated conduction along 3-fold linkages or chains with variable range and variable orientation hopping. Thermal annealing leads to chain ripening and a reduction in the activation energy for transport.
Insulator-Metal Transition Induced by Pressure in Pb1-xGexTe Doped with Yb
Authors: Skipetrov E. P. , Chernova N. A. , Slyn'ko E. I. , Vygranenko Yu.K. 
Published: April 2011

ABSTRACTIn this paper the galvanomagnetic properties (4.2≤T≤300 K) of Pb1-xGexTe(x≤0.038) doped with Yb were investigated both under atmospheric pressure and under hydrostatic compression up to 12 kbar. The variation of the energy diagram of Pb1-xGexTe<Yb> under variation of Ge concentration and under pressure were proposed. It was shown that change of the energy spectrum under pressure leads to the insulator-metal transition due to redistribution of electrons between the valence band and the deep Yb level. By comparing theoretical and experimental dependences of hole concentration on pressure the parameters of the Yb-induced deep level were determined.
High Pressure Study of III-Nitrides and Related Heterostructures
Authors: Shan W. , Ager J. W. , Walukiewicz W. , Haller E. E. , Little B. D. , Song J. J. , Goldenberg B. , Feng Z. C. , Schurman M. , Stall R. A. 
Published: April 2011

ABSTRACTWe present results of photoluminescence (PL) studies of GaN, InxGa1-xN and AlxGa1-xN alloys, as well as related thin film heterostructures under hydrostatic pressure using the diamond-anvil-cell technique. The GaN PL spectra are dominated by strong and sharp near-band-edge luminescence associated with annihilations of bound excitons and intrinsic free excitons in the crystals. The spectrally well-resolved emission lines allow us to accurately determine their pressure. The PL spectra of InxGa1-xN and AlxGa1-xN epitaxial films were found to exhibit strong near-band-edge luminescence emissions. By examining the pressure dependence of these spectral features, the pressure coefficients for the PL emissions associated with the direct Γ band gap of InxGa1-xN and AlxGa1-xN were determined for the first time.
Thermal Plasma Synthesis of Fe-Co Alloy Nanoparticles
Authors: Scott John Henry J. , Turgut Zafer , Chowdary Krishna , Mchenry Michael E. , Majetich Sara A. 
Published: April 2011

ABSTRACTFeCo nanoparticles are synthesized in a radio frequency (RF) plasma torch from metal powder precursors and simple gases. The first precursor consists of pre-alloyed FeCo powder; the second precursor is a mixture of elemental Fe and Co powders. A protective carbon coating on the particles is achieved by injection of acetylene gas into the plasma. X-ray diffraction reveals phase purity, low carbon concentration, and minimal oxidation. Analytical electron microscopy is used to examine the nanocomposite morphology and composition of individual nanoparticles. Both synthesis routes produce alloy product, but nanoparticles produced from pre-alloyed precursors exhibit smaller variations in Fe/Co ratio than particles produced from elemental powders.
Chemical Synthesis of Nanostructured Powders and Coatings using the Polyol method
Authors: Chow G. M. , Kurihara L. K. , Feng C. R. , Martinez-Miranda L. J. , Lawrence S. H. 
Published: April 2011

ABSTRACTAn overview of our work on the synthesis of nanostructured powders and coatings using the polyol process is presented.
Assembly of polymer microspheres and the thin-film Micropatterning
Authors: Du H. , Qian X. M. , Li W. M. , Liu F. Q. , Tang J. , Tang X. Y. , Bai Y. B. , Li T. J. 
Published: April 2011

ABSTRACTCopolymer latexes of poly(styrene/acrylic acid) were closely packed into two-dimensional arrays on glass, mica and silicon substrates respectively. When the small latexes were negatively charged due to −SO4− and −COO− groups on the surface, their film formation, in some degree, was affected by the electrostatic interaction between two particles as well as capillary force. Different electrolytes were added into the colloid to adjust the particle interaction so that the attractive and the repulsive forces were properly balanced and the ordered arrays were achieved. Thin metal film was deposited on the latex monolayer through thermal evaporation in vacuum. Then, the spheres were dissolved away to leave behind a surface with features located where the interstitial spaces between the densely packed spheres had been. This process depended upon the interaction between the microspheres and the substrates, and the adhesion between the film materials and the substrates. Different patterns of honeycomb net, triangle islands and separate spots can be obtained by controlling the ultrasonic time and intensity.
Analysis of hetero-coagulation structure of colloidal mullite precursor powder - experimental approach and computer simulation -
Authors: Cho Y. I. , Kamiya H. , Takano H. , Horio M. , Suzuki H. 
Published: April 2011

ABSTRACTTo control the hetero-coagulation structure of ultra-fine γ-A12O3and SiO2powders for mullite ceramics, hetero-coagulation structures in suspensions with different pH conditions were investigated by experimental approach and computer simulation. Electrophoretic mobility distribution, which was determined by a Laser Doppler method, was used for the estimation of hetero-coagulation structure. As results, a bimodal electrophoretic mobility distribution was observed when precursor powders were prepared by colloidal mixing processes at pH=9.5. Since each peak almost corresponded to the electrophoretic mobility of γ-A12O3or SiO2particles, hetero-coagulates were not formed in suspension. In the case of pH=6.0, heterocoagulates generated in suspension, however, uniform and fine hetero-coagulates could not be attained. On the other hand, narrow and single mode electrophoretic mobility distribution was observed after colloidal mixing at pH=4.4. The change of hetero-coagulation structure with different pH conditions were analyzed by using Brownian dynamic methods with considering hetero-coagulated system. The change of hetero-coagulation structure with different pH conditions were qualitatively simulated by this model.
Direct observations of the sintering of silver nanoparticles on single crystal copper by in-situ uhv tem
Authors: Yeadon M. , Yang J. C. , Averback R. S. , Bullard J. W. , Gibson J. M. 
Published: April 2011

ABSTRACTUsing a novel ultrahigh vacuum (UHV) transmission electron microscope with in-situ UHV sputtering attachment we have studied the sintering of copper and silver nanoparticles with single crystal copper substrates. Copper and silver particles deposited on (001) copper initially assume random orientations. Upon annealing, however, the particles reorient and assume an epitaxial orientation with the substrate. In the case of copper on copper, homoepitaxy occurs by a process involving sintering and grain growth. In the case of silver on copper, we have observed the particles to wet the substrate surface and sinter to form a thin epitaxial film with the orientation relationship (111)Ag // (001)Cu, [110]Ag // [110]Cu.
Theoretical modeling for laser cleaning of micro-particles from solid surface
Authors: Lu Y. F. , Song W. D. , Hong M. H. , Chan D. S. H. , Low T. S. 
Published: April 2011

ABSTRACTIn laser cleaning of micro-particles from solid surface, the adhesion force between the particles and the substrate surface and the thermal expansion of both particles and substrate play important roles in determining the threshold laser fluence. Taking Van der Waals force and cleaning force due to fast thermal expansion of particles and substrate surface induced by pulsed laser irradiation into account, a cleaning model was established for removal of tiny particles from substrate surfaces. The cleaning condition and cleaning threshold can be obtained from this model. This model can qualitatively and quantitatively predict how the laser cleaning process depending on laser incident direction, laser wavelength, particle size, particle material and substrate material. Theoretical predictions have been verified by the experimental results. Laser cleaning of micro-particle has wide applications in microelectronics and magnetic recording industries.
Structural Changes on SnO2 Nanoparticles for Gas Sensor Applications induced by Calcination Treatments and Grinding
Authors: Diéguez A. , Alay J. L. , Kappler J. , Romano-Rodríguez A. , Vilà A. , Bârsan N. , Weimar U. , Göpel W. , Morante J. R. 
Published: April 2011

ABSTRACTStarting with a hydrated tin dioxide powder of 3nm size obtained by the sol-gel method, the effects of thermal treatments and grinding on the final structural properties of the nanoparticles have been investigated. It is observed that two regions with different structural properties can be distinguished in the range of temperatures between 250 and 1000°C. In spite of their large grain size (>15nm), above 350–450°C, these nanocrystals can be used as precursor powders for gas sensors because of their higher stability. Grinding of the starting material before calcination will be proved as a suitable method to obtain the sarne type of stability with lower grain size.
Defect Production and Annealing in High-Tc Superconductor Euba2cu3oy Irradiated with Energetic Ions at Low Temperature
Authors: Ishikawa N. , Chimi Y. , Iwase A. , Tsuru K. , Michikami O 
Published: April 2011

ABSTRACTThe in-situ measurement of fluence dependence of electrical resistivity at 100K has been performed for EuBa2Cu3Oy irradiated at 100K with various energetic ions (Cl, Ni, Br, and I) at energy of 90–200MeV. Decreasing slope of resistivity-fluence curves has been observed for irradiations with 120MeV Cl, 90MeV Ni, and 185MeV Ni, while increasing slope of the curves has been observed for irradiations with 120MeV Br, 125MeV Br, and 200MeV I. It is assumed that the damaged region has a cylindrical shape along ion path and a higher resistivity than the undamaged matrix region. The calculated resistivity-fluence curve fitted well with the experimental data when using the diameter and the resistivity of the damaged region as fitting parameters. The obtained diameter and the resistivity of the damaged region have increased with increasing the electronic stopping power, Se. Successive annealing of the specimens up to 300K after irradiation has resulted in 50–70% recovery of irradiation-induced resistivity change at 100K. The diameter of the damaged region has been larger than that of amorphous tracks observed by transmission electron microscope. This result is discussed in relation to the result of annealing experiment.
Improvement of Hydriding Property in ZrNi Alloy by Means of Implantation
Authors: Suda T. , Yonezawa T. , Arashima H. , Ohnuki S. , Kabutomori T. 
Published: April 2011

ABSTRACTIon-implantation was applied to the surface modification of ZrNi for improving the surface activation of hydrogen absorbing alloys. At the condition of low temperature, only implanted areas showed micro-cracks and pulverization. At high temperature, the reaction was very rapid and both implanted and shielded areas showed the pulverization. The results indicate hydrogen ion-implantation can enhance the activation of this alloy, and the roles of radiation-induced implanted hydrogen and surface film are discussed.
Aluminum Acceptors in Inequivalent Sites in 4H-Sic
Authors: Smith S.R. , Evwaraye A.O. , Mitchel W.C. 
Published: April 2011

AbstractP-type conductivity is normally produced in silicon carbide by doping with Al or B. The aluminum atom substitutes for silicon in the SiC lattice. Several studies have shown that nitrogen, which substitutes for carbon atoms and produces n-type conductivity in SiC, sits at the two inequivalent lattice sites in 4H-SiC, and two N activation energies of 53 meV (h) and 100 meV (k) have been reported.Hall effect measurements and infrared absorption studies of SiC doped with Al showed only one Al activation energy, however, and the published Al activation energy in SiC (3C, 4H, and 6H) ranges from 191 meV to 280 meV. This has lead to the general conclusion that the activation energy of Al acceptors in SiC does not depend on the polytype or on the lattice site occupied.Thermal Admittance Spectroscopy (TAS) has been used to determine the activation energy of Al in 4H-SiC specimens where NA-ND ranged from 7.2 × 1015 cm2to 5.6 × 1018 cm−2. By analogy to B in 6H-SiC, we propose two levels for Al in 4H-SiC at Ev + 0.212 eV and Ev + 0.266 eV.
Investigation of the Effect of Thermal History on Ring-OSF Formation in CZ-Silicon Crystals
Authors: Kelly G.P. , Hourai M. , Umeno S. , Sano M. , Tsuya H. 
Published: April 2011

AbstractR-OSF are known to appear in CZ silicon crystals, but their nuclei are not observable in the as-grown state, and as-such have been difficult to characterize. Using a crystal grown with modifications in its pulling rate, this paper used lifetime in particular, coupled with the OPP, to investigate as-grown OSF nuclei size and density distribution and to discuss further how R-OSF are formed and how their formation interacts with that of other defects. It was found that faster cooling in the temperature range where large voids are formed (1070°C-970°C), which resulted in a larger residual vacancy concentration, caused the OSF ring to become wider, and the OSF-nuclei to become larger than normal in this area, while fast cooling in the temperature range where OSF are formed (990°C-900°C) is thought to suppress their formation, which thus resulted in smaller OSF-nuclei
Investigation of Influence of Thermal and Radiation Processing on Impurity Centers in Silicon and Silicon Based Structures
Authors: Ashurov M. , Makhkamov Sh. , Tursunov N.A. , Martynchenko S.V. 
Published: April 2011

AbstractIn this paper the results of studies of the influence of radiation and thermal processing on activation of impurity centers (Au, Ag, Pt, Rh) in p-n-structures based on doped silicon are presented. It is shown that the thermal processing in the temperature range of 600-700°C leads to significant increasing of the concentration of electrically active impurities in the samples irradiated by, -rays as compared to the non-irradiated samples as well as to increasing of their decay temperature. These effects depend on the type and fluence of irradiation and can be explained by formation of additional electrically active states of impurities due to decay of complexes of radiation defects and electrically non-active impurities. A possible mechanism of activation process of impurity centers in silicon under radiation and thermal processing is discussed.