bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radiation Degradation of Nanomaterials
Authors: Raffaelle Ryne , Cress Cory D. , Wilt David M. , Bailey Sheila G. 
Published: April 2011

ABSTRACTWe have been developing a variety of nanomaterials for their use in power devices. An example of this is our use of both single wall carbon nanotubes and several varieties of semiconducting quantum dots (e.g., CuInS2, CdSe, InAs) for use in space solar cells. The ability of these materials to withstand the rigors of the space radiation environment will be essential for this intended application. In addition, we have also been developing both nanostructure III-V devices and radioluminescent quantum dots for use in radioisotope batteries. In this application these nanomaterials are subjected to an extremely high radiation level. Their degradation rate will be the key to determining the ultimate lifetime of these power supplies, which in principle can have an energy density that is orders of magnitude higher than any conventional battery chemistry. The nanomaterials included in this study were subjected to alpha particles fluences and the degradation in various properties were monitored using different analytical techniques. Specifically, the radioluminescence of the quantum dot intended for use in the radioisotope batteries was monitored as a function of fluence. In the case of the III-V quantum dots, their photoluminescent degradation as a function of fluence was measured in comparison to the bulk substrate on which the quantum dots were grown. Finally for the carbon nanotubes, relative intensities of the Raman peaks associated with their inherent vibrational modes was used to monitor the effects of the alpha radiation damage. Results on the radiation tolerance of these nanomaterials and its implication with regard to their ultimately utility in power devices are presented.
Degradation of Nano-crystalline ITO Films due to Exposure to Hyperthermal Atomic Oxygen
Authors: Li Long , Harder Ross , Xu Fengting , Robinson Ian K. , Yang Judith C. 
Published: April 2011

ABSTRACTIndium tin oxide (ITO) films coated on float glass slides were exposed to 5 eV hyperthermal atomic oxygen at room temperature with increasing fluences: 2×1019, 6×1019 and 2×1020 O-atoms/cm2. We characterized the structure of the ITO films after room temperature atomic oxygen exposure with scanning electron microscope (SEM) and atomic force microscope (AFM), synchrotron X-ray diffraction (XRD), and cross-sectional transmission electron microscope (X-TEM). The unexposed ITO films were found to possess a nano-crystalline surface, and clean and abrupt ITO/SiO2 interfaces without interfacial phase. Surface roughness of the exposed ITO films increased with the increasing AO influences. The interface- sensitive peaks in XRD measurements with grazing incidence revealed that the crystallinity of the ITO was modified near the interface. Cross-sectional TEM confirmed that many ITO particles with diameters ranging from 2-10 nm formed in the SiO2 substrate near the interface after AO exposure. These findings suggest that O atoms can travel through the ITO films, where the boundaries of columnar-grown grains may supply the pathway.
Self-Lubrication of Machining Tools in Dry via In-situ Formed Tribofilms
Authors: Aizawa Tatsuhiko , Yamamoto Shigeo , Sumitomo Taro 
Published: April 2011

ABSTRACTGreen manufacturing technology has become a significant innovative keyword to reduce the environmental burden and CO2 emission at the stage of manufacturing and production. In daily operations by machining, huge amount of lubricating oils and cleansing agents is wasted so that dry machining technology provides us a way to completely reduce these wastes. Among several candidates, self-lubrication via in-situ formation of lubricious oxide films is accommodated to protective coatings in order to attain low friction and wear state even at higher cutting speed range. Materials science of in-situ formed lubricious oxide tribofilms is stated with consideration of accommodation mechanism via the chlorine implantation. Mechanical characterization is made for evaluation on elasto-plastic deformation of lubricious oxides. Turning test is employed to evaluate dry machinability of various tools for wide range of cutting speed. Self-lubrication in dry machining is described both for bare WC and TiCN-coated WC tools with and without chlorine implantation. Precise microstructure analyses are made by using the laser microscope, EDS and XPS. In-situ formation of lubricous oxides proves that self-lubrication process takes place even in dry machining to reduce the flank wear and friction coefficient.
Deposition of Adherent Diamond Coatings on WC-Co Substrates
Authors: Xu Zhenqing , Lev Leonid , Lukitsch Michael , Kumar Ashok 
Published: April 2011

ABSTRACTHigh quality well-adhered microcrystalline diamond coatings have been produced by the microwave plasma enhanced chemical vapor deposition (MPECVD) technique on cemented carbide substrates. A multi-interlayer system Cr/CrN/Cr was deposited on the WC-Co substrate before diamond deposition to work as a diffusion barrier. The coated substrate was peened with friable diamond powder to roughen the surface resulting in high nucleation density. Adherent diamond film has been successfully deposited on the substrate at temperature around 700°C with 1.0 % CH4 in Hydrogen plasma. The surface morphology and film structure has been studied by Scanning Electron Microscopy (SEM) and X-Ray diffraction technique. The adhesion of the diamond film has been evaluated by Rockwell indentation tests.
Development of Multilayer TiAlN + γ–Al2O3 Coatings for Difficult Machining Operations
Authors: Bobzin K. , Lugscheider Erich , Knotek O. , Maes Michel , Immich Philipp , Piñero Carmen 
Published: April 2011

AbstractThe continuous advances in the aircraft and nuclear industry demand the development of new materials that among other properties offer a good resistance at elevated temperatures. For this reason, Ni super alloys were developed from a simple Ni-Cr matrix to multi-element, multi-phase systems. These new super alloys are specially favored for their exceptional thermal resistance and ability to retain mechanical properties at elevated temperatures. They are classified as difficult-to-machine materials due to their high shear strength, work hardening tendency, content of abrasive carbide particles within the microstructure, strong tendency to weld and to form built-up edges. Their low thermal conductivity leads to elevated temperatures during machining. Consequently, their tendency to maintain a high strength at elevated temperatures leads to elevated cutting forces. On this account, the development of an adequate coating for machining Ni alloys is today an important challenge. Nowadays, TiAlN is well known because of its excellent overall cutting performance. However, Al2O3 possesses better chemical and thermal properties than TiAlN, especially regarding hot hardness, oxidation resistance, diffusion resistance. Motivated by the advantages offered by PVD-Technology, γ-Al2O3 was synthesized by reactive bipolar pulsed magnetron sputtering in previous works. PVD-Processes allow the deposition of insulating coatings such as alumina at reduced temperatures, which implies a lower substrate thermal load. At the same time using PVD-Technology it is possible to produce high compressive stresses in the coatings (high alternating thermal stress resistance), keep sharp cutting edges, synthesize pure structures and deposit various coating combinations such as multilayer multilayer TiAlN + γ-Al2O3. Therefore, a PVD-multilayer coating TiAlN + γ-Al2O3 is very promising for machining of Ni alloys such as Inconel 718. However, due to the very different characteristics of the nitrides and oxides, particularly the good coating cohesion of this coating concept constitutes a challenge. In this work different multilayer combinations were deposited on cemented carbide cutting inserts. In order to improve the adhesion between the nitride and oxide layers and consequently the coating cohesion, a special gradation was developed. The reactive gas flows (N2 and O2) was gradually changed during the coating deposition. The result was a soft gradation consisting of different nitrides and oxides species synthesized in very thin layers. Tribological tests demonstrated that the developed soft gradation offers an important improvement of the coating cohesion and fatigue resistance. For the evaluation of the coating adhesion and cohesion calo-, Rockwell- and scratch-tests were carried out. Mechanical properties were investigated by impact.
Metal micromolding with surface engineered inserts
Authors: Cao Dongmei , Jiang J. , Meng W. J. 
Published: April 2011

AbstractThe LiGA (Lithographie, Galvanoformung, Abformung) technique is a leading micromanufacturing process for making polymer- and metal- based high-aspect-ratio microscale structures. Molding replication is the key LiGA step for economical mass production of metal-based HARMS. Using a hybrid technique, we have fabricated microscale Ta mold inserts. Surface engineering of Ta inserts by electrochemical polishing followed by conformal coating deposition has enabled successful high-temperature micromolding of Al and Cu. In this paper, the molding performance of Ta inserts coated with amorphous hydrogenated carbon based coatings and amorphous silicon nitride based coatings is compared. Issues of maximum molding force, demolding force, and coating durability are addressed.
Design and calculation of advanced microstructural patterns by laser interference metallurgy
Authors: Lasagni Andres Fabian , Holzapfel Christian , Mücklich Frank 
Published: April 2011

ABSTRACTLaser Interference Metallurgy is a recently developed method for the laser material surface modification by which various interference patterns can be transformed directly, permanently, and efficiently to the surfaces of different kinds of materials. By using of this technique, different metallurgical effects such as melting, recrystallization, quenching, recovery, defect or phase formation can be exploited. In this work, advanced microstructural patterns are designed by means of the two dimensional Fourier Transformation. After that, the geometrical configuration for the laser interference experiments is calculated. Finally, thin metallic films are irradiated in order to demonstrate the viability of the presented method. The resulted structures were studied by means of Focus Ion Beam and Transmission Electron Microscopy. These surfaces represent a new type of long ordered topographical as well chemical patterns which might be applicable for well defined surface functionalization.
Ultra sensitive Bio-Chemical sensors Based on Optical Resonance
Authors: Prasad Shalini 
Published: April 2011

ABSTRACTWith the focus on bio terrorism and environmental sensing, there is need for development of smart integrated bio-chemical sensors. We investigate Whispering Gallery Mode (WGM) based High Q micro cavity as a biosensor. We integrate the lab-on-a-chip approach with High Q technology to develop highly selective and smart sensors for in-situ detection of aqueous media based agents. We have investigated the ring based micro-cavity structure as a sensor. We identify the detection of agent through the changes observed in the wavelength shift and Q factor as a result of enzyme-substrate interactions. We report an experimental demonstration of a compact micro-cavity based biochemical sensor based on the micro ring structure. The micro-cavity, fabricated on a silica-on-silicon substrate, is designed to have a resonant wavelength (l) near 1.34 μm. The transmission spectrum of the sensor is measured with different ambient refractive indices ranging from n =1.0 to 1.5. Chemical detection was achieved by measuring the shift in resonant wavelength, and variation to the quality factor
Oscillatory Temperature-driven Morphological Relaxation of Surface Ripple Using Weak Pulsed Laser
Authors: Khenner Mikhail 
Published: April 2011

ABSTRACTA continuum (Mullins-type) model is proposed for the non-isothermal, isotropic evolution of a crystal surface on which mass transport occurs by surface diffusion. The departure from constant temperature is assumed induced by low-energy incident pulsed radiation. It has been previously shown experimentally and theoretically that such heating mode gives rise to the quasistationary regime, in which the surface temperature of a thick solid film oscillates about the mean value with the pulse repetition frequency. The implications of oscillatory driving with high frequency values on relaxation of surface ripple are examined; in particular, the traveling wave solutions with decreasing amplitude are detected numerically. Pulsed heating also results in faster smoothing of the ripple, compared to the case when the surface is at constant temperature which is same as the mean temperature in the pulsed heating mode. Impact on ripple shape is minor for ripple amplitudes considered.
Real time measurement of photochemical surface reactions by using a total reflection prism
Authors: Sato Yuki , Sato Yuji , Murahara Masataka 
Published: April 2011

ABSTRACTThe photochemical reaction processes, i.e., photo-dissociation of a reaction solution, defluorination of fluorocarbon [FEP], and substitution of a hydrophilic group, were measured in real time, when irradiating a Xe2 excimer lamplight on the water or ammonia solution as a reaction solution and FEP placed on the attenuated total reflectance [ATR] prism. In case of ammonia solution, with the increase in irradiation time, the absorption peaks of 3300 cm−1 and 1650 cm−1 gradually decreased, and the new absorption of -CF2-NH2 gradually appeared at 1410 cm−1, which presented the strongest absorption after UV irradiation for 25 minutes. The results indicate that the ammonia water has turned to amino groups. In addition, the contact angle of water was measured. When compared to the untreated sample, whose contact angle was 110 degrees, the contact angle of the sample treated with water became 31 degrees after the Xe2 lamp irradiation for 25 minutes, and that of the sample modified by ammonia water further improved to 27 degrees after the irradiation for 25 minutes.
Electrowetting–induced photochemical surface modification onto fluorocarbon
Authors: Anai Hiroyuki , Sato Yuji , Murahara Masataka 
Published: April 2011

ABSTRACTThe PTFE was modified into hydrophilic with 1/100 of the shots number required to obtain the same contact angle with water by the laser irradiation alone, when irradiating an ArF excimer laser on the sample surface at the moment of applying a 6 kV to the water placed on the PTFE surface to decrease the contact angle with water.A plasma treatment method is widely used for plastic surface modification, but the hydrophilic property generated by this method fades away soon. On the other hand, we have previously reported that the ArF excimer laser light was applied on a sample surface in the presence of water to substitute hydrophilic groups, which was modified to have a long–lasting hydrophilic property. This method, however, needed 3000 to 10000 shots of the laser irradiation, and it is less economical compared with the plasma processing that requires only one–minute irradiation. There is an electro–wetting method, in which the contact angle with water decreases temporarily when a high voltage is applied between the water and the sample, but the contact angle is restored to its original position when stopping the voltage application.Thus, we demonstrated the surface modification of PTFE maintaining the hydrophilic property for a long period with only 100 shots, by irradiating the ArF excimer laser on the sample at the moment when the wettability became high by the electro–wetting method. Water was placed in the gap between the silica glass and the PTFE to create a thin liquid layer with capillary phenomenon. A high voltage (6 kV) of direct current (DC) or alternating current (AC) was applied on the gap, and the ArF excimer laser was vertically irradiated on the sample surface. The water was photo–dissociated to produce H and OH. At the same time, the C—F bond of the PTFE was also photo–dissociated, and the F atom bonded to the H atom to produce HF. The OH group united with the dangling bond of C, which resulted in modifying the PTFE surface to be hydrophilic.To evaluate the wettability of the modified sample, the contact angle with water was measured. Improving the contact angle with water from 110 degrees for the untreated sample to 50 degrees for the treated sample had needed 10000 shots at the laser fluence of 5 mJ/cm2. By combined high voltage application and ArF excimer laser irradiation treatments, however, the 50–degree contact angle was yielded with 500 shots, 1/20 of 10000, when applying the DC of 6 kV, and with 100 shots only, 1/100 of 10000, when applying the AC of 6 kV. Moreover, the modified sample was observed for a change in contact angle with passage of time. The contact angle was 60 degrees after applying the high voltage, and 110 degrees when stopped. On the other hand, the sample modified by combined the high voltage application and ArF excimer laser irradiation maintained the 50–degree contact angle for one month after stopping the voltage application.
Conformal deposition of a silicon-oxide and a fluorocarbon on a nano-shaped material in supercritical carbon dioxide
Authors: Shimizu Takashi , Ishii Kenichi , Suzuki Eiichi 
Published: April 2011

ABSTRACTA novel surface engineering of nano-shaped materials, i.e., surface coating in supercritical fluid is proposed. Conformal deposition of a silicon-oxide thin film in supercritical carbon dioxide (scCO2) where O2 gas is miscible as an oxidizing agent is demonstrated. A uniform silicon-oxide film has been deposited even on backside of a nano-shaped SiO2, which is hard in the standard chemical vapor deposition. Filling of a Si-oxide into the horizontal gap has also been successfully achieved. Deposition of a fluorocarbon in scCO2 were tried to investigate surface modification using scCO2 and a hydrophilic SiO2 surface became water-repellent after the surface modification. These results indicate that the developed surface engineering in the supercritical fluid is promising technology in nanoscale device fabrication and micro (nano-) electromechanical systems.
Melt Fracture of Polymer Thin Film at Strongly Attractive Surfaces
Authors: Li Chunhua , Jiang Jun , Rafailovich Miriam H. , Sokolov Jonathan C. 
Published: April 2011

ABSTRACTIn this study, we report an interesting phenomenon of “melt fracture” which was observed when a high viscosity film dewets from a film of lower viscosity. We propose that this phenomena is similar to the “melt fracture” or “shark skin” that is observed when extruding bulk polymer. We hypothesized that the “melt fracture” occurs as a result of shear which is imposed by the dewetting layer on the visco-elastic lower layer. The dewetting layer is adhered to the lower layer via entanglements across the polymer/polymer interface. When the other interface of the liquid film is adsorbed to an attractive substrate interface, a velocity gradient occurs in the film and therefore can result in the shear gradient. We proposed that if this shear rate exceeds the natural reptation time, melt fracture of thin film resulted. Screening the substrate interaction by first deposition a very thin layer of immiscible polymer such as poly (vinyl-pyridine) PVP reduced the degree of melt fracture. A DI 3000 Atomic Force Microscopy (AFM) was used to quantify the depth and the dynamics of the melt facture process.
Mid-IR Interband Cascade Lasers
Authors: Yang Rui Q. , Hill Cory J. , Qiu Yueming 
Published: April 2011

ABSTRACTEfficient mid-IR interband cascade (IC) lasers have been developed based on III-V semiconductor materials with lasing emission covering a wavelength range from 2.7 to 5.6 microns. These IC lasers reuse injected electrons in cascade stages for photon generation with high quantum efficiency to achieve high output powers. Also, IC lasers have a low threshold current density with a very efficient use of applied voltage, resulting in reduced power consumption. Single-mode distributed feedback lasers have been made, and integrated into aircraft and balloon instruments which made atmospheric measurements of CH4 and HCl. In this work, the characteristics of IC lasers and their recent developments are reviewed.
Analysis of the Front Facet Temperature in Laser Diode With Non Absorbing Mirror
Authors: Ochalski Tomasz Jan , Pierscinska Dorota , Malag Andrzej 
Published: April 2011

ABSTRACTNon-absorbing mirror (NAM) lasers, also known as window lasers, were developed to increase catastrophic optical damage level of the devices. In this work we present the analysis of the laser diodes (LD) front facet temperature distribution. Micro-thermoreflectance technique is used to perform a detailed temperature maps of the operating LDs. Such a technique gives us temperature maps with a high spatial resolution equal 0.6μm. We demonstrate micro thermoreflectance as a perfect tool to determine real temperature distribution of the operating laser diode front facet.
InAs/In0.15Ga0.85As1−xNx quantum dots for 1.5 μm laser applications
Authors: Richter Mirja , Damilano Benjamin , Massies Jean , Duboz Jean-Yves , Wieck Andreas D. 
Published: April 2011

ABSTRACTSelf-assembled InAs quantum dots (QDs) on GaAs substrate encapsulated with In0.15Ga0.85As1−xNx (GINA) have been grown by solid source molecular beam epitaxy, using optimal growth temperatures and rates for each of the two layers. The photoluminescence (PL) intensity increases for annealed samples. The optimum annealing temperature depends on the nitrogen composition. InAs QDs overgrown with larger nitrogen mole fraction GINA show a smaller PL peak blue-shift after annealing. Intense and narrow PL emission in the 1.5 µm range is achieved for samples annealed at optimal temperature.
Electron emission mechanism of diamond characterized by combined XPS/UPS/FES
Authors: Yamaguchi Hisato , Yamada Takatoshi , Pate Bradford B. , Kudo Masato , Takakuwa Yuji , Okano Ken 
Published: April 2011

ABSTRACTDiamond has various advantages as an electron emitter in addition to the low-threshold voltage, negative electron affinity (NEA), high thermal conductivity, high mechanical hardness, and high chemical stability. The difficulty in clarification of electron emission mechanism is preventing diamond from being used in the practical use. It is extremely difficult to identify the surface potential of the emitting diamond from conventional Emission current (I)- Anode voltage (V) characteristics. If one could measure the potential of the emitting surface, the band diagram of emitting diamond can be completed. The combined spectroscopy of XPS/UPS/FES specially built for this study, is one of the most powerful tool, which could identify the potential of the emitting surface. In this study, we have succeeded in observing the origin of field-emitted electrons using our combined XPS/UPS/FES system.
Fabrication of planar SiON optical waveguide and its characterization
Authors: Cho Yu-Jeong , Kim Yeong-Cheol 
Published: April 2011

ABSTRACTSilicon oxynitride (SiON) was deposited as a core layer on a silica (SiO2) under-cladding layer by using plasma enhanced chemical vapor deposition (PECVD). The refractive index of the SiON core layer was varied between 1.45 and 1.78 by changing the gas flow ratio of SiH4, N2O and NH3. Etching experiments were performed using a dry etching equipment to fabricate the SiON core. An optical planar waveguide with a core and under-cladding thicknesses of 6 μm and 8 μm, respectively, and a refractive index contrast (Δn) of 7 % has been fabricated.