bluuebunny/crossref_metadata_2025_split huggingface dataset:
Brllouin Light Scattering on Diamond and Diamondlike Carbon Films
Authors: Jiang X. 
Published: March 2011

ABSTRACTThe set of acoustic mode frequencies associated with elastic constants has been determined from Brillouin light scattering measurements on carbon films of different crystallographic phases, i.e. on chemical vapour deposited (CVD) polycrystalline diamond, polycrystalline graphite, and amorphous carbon films (a-C:H). From the measured sound velocities of the acoustic phonons Young's moduli, shear moduli, and bulk moduli of the films were calculated. On a-C:H films depth-sensing indentation tests were performed. The values of ultramicrohardness of these films are, therefore, also reported.
Practical Application of a Geometrically Nonlinear Stress-Curvature Relation
Authors: Masters Christine B. , Salamon N. J. 
Published: March 2011

ABSTRACTA recently developed geometrically nonlinear stress-curvature relation based on a minimization of the total strain energy, which predicts a bifurcation in shape as the magnitude of intrinsic film stress increases, is discussed in this paper. It is compared with the linear theories of Stoney and Brenner & Senderoff for a thin molybdenum film on silicon substrates with various thicknesses. Although the ratio of film to substrate elastic modulus is only 2, Stoney's equation generates significant error for this film/substrate system and the Brenner & Senderoff relation should be used for calculating initial film stress when plate deflections are small. When deflections exceed approximately half the substrate thickness the Brenner & Senderoff equation produces over 10% error and consequently, the nonlinear stress-deflection relation should be used to relate plate curvatures to initial film stress.
Time-Dependent Deformation in Room-Temperature Indentation Experiments using a Nanoindenter
Authors: Baker Shefford P. , Barbee Troy W. , Nix William D. 
Published: March 2011

ABSTRACTTime-dependent deformation in room-temperature indentation is a well known phenomenon which is frequently overlooked in depth-sensing indentation experiments. In this study, the time-dependent displacements which occur during depth-sensing indentation experiments using a Nanoindenter were investigated. Time-dependent displacements were found to result both from plastic deformation of the sample and experimental drift. A simple correction for experimental drift was applied in experiments on sputtered copper thin films and reasonable strain rate sensitivities were obtained. The sources of experimental drift were identified and measured. It appears to be possible to measure the rate-dependence of plastic deformation in a variety of materials using this instrument.
Stress—Strain Behaviour of thin films using a Spherical Tipped Indenter
Authors: Bell T. J. , Field J. S. , Swain M. V. 
Published: March 2011

ABSTRACTThe stress—strain behaviour of metallic and polymer thin films are measured using a spherical indenter. A modification of the Hertzian analysis enables the elastic to plastic transition to be analyzed so that the variation of mean pressure versus depth can be calculated. The stress—strain behaviour is then calculated from the mean indentation strain using a relationship proposed by Tabor[l]. Observations of high precision load displacement data generated with a UMIS—2000 instrument are analyzed on the basis of the simple analysis developed. The measured values are compared with simulated data for the same materials.
The Elastic, Plastic, and Time Dependent Properties of thin Films as Determined by Ultra low Load Indentation
Authors: Lucas B. N. , Oliver W. C. 
Published: March 2011

ABSTRACTUsing a highly spatially resolved mechanical properties microprobe, the elastic, plastic and time dependent mechanical properties of sapphire and a 1.9 μm amorphous alumina film on a sapphire substrate have been studied. Young's modulus, hardness, and stress-exponent data are reported. The technique for characterizing time dependent properties via indentation (hardness versus displacement rate/displacement) are directly compared to standard uniaxial compressive techniques (stress vs strain rate) for a bulk Pb-In alloy to further quantify the relationships between the two techniques.
The Generation and Optical Activity of Misfit Dislocations by Very Low Level Transition Metal Contamination of SiGe/Si.
Authors: Kightley Philip , Higgs Victor , Goodhew Peter J 
Published: March 2011

ABSTRACTAn initially pseudomorphic Sio.93Geo.07 layer is forced to relax after the deposition of 0.003 monolayers of Cu contamination and a 600°C anneal. Photoluminescence shows the dislocations have similar luminescence features (D1 to D4) to dislocations generated in bulk silicon. TEM is used to study the generation of the misfit dislocations. It is shown that the half loops form at the sample surface and a mechanism that involves the action of both the metal contaminant and the surface steps is suggested to explain the geometric arrangement of the dislocation loops that are present. The sample was found to be only 22% relaxed whereas equilibrium theory predicts 92% relaxation.
High Resolution X-Ray Studies of Ga1–xInxAs Epilayers on GaAs Substrates
Authors: Shi Yushan , Sutton Mark 
Published: March 2011

ABSTRACTBy using the techniques of normal Bragg scattering and glancing incidence scattering, we have measured both the out-of-plane and in-plane structures of GaixInxAs epilay-ers grown on GaAs (001) face by MOVPE. The data presented in this paper were collected from two samples: a thick epilayer of 40, 000A Ga0.84In0.16As, and a thin epilayer of 500Å Ga0.84In0.19As, which are lattice-mismatched with the substrate by about 1.14% and 1.36% respectively according to the Vegard's law. The measured average lattice constants of the thick epilayer agree with the expectation both out-of-plane and in-plane and show nearly complete structural relaxation. An uniaxial in-plane modulation in the thick epilayer has been observed. The out-of-plane and in-plane data of the thin epilayer demonstrate a tetragonal distortion of the lattice, and the Poisson's ratio is calculated to be 0.36. The averaged in-plane lattice constant is still 0.18% larger than that of the substrate, which results in a complex structure at the epitaxial interface. An in-plane misalignment along one (110) axis in the thin epilayer has been observed.
Strain Relaxation in Heteroepitaxial Ge/Si Structures by Annealing Under Ultra High Pressure
Authors: Ishiwara Hiroshi , Sato Takayoshi , Sawaoka Akira 
Published: March 2011

ABSTRACTA novel method to solve the thermal mismatch problems in a heteroepi-taxial structure is presented, in which an amorphous film deposited on a single crystalline substrate is crystallized in solid phase by annealing under ultra high pressure and both temperature and pressure are decreased proportionally. Under a specific relation between the temperature and pressure, it is expected that the effective thermal expansion coefficients, the expansion coefficients modified by elastic strain, of the film and substrate are equal and that neither defects nor strain is generated in the film during the cooling process. Theoretical consideration and experimental results for Ge films on Si(100) substrates are presented.
Effect of Deposition Conditions on Intrinsic Stress, Phase Transformation and Stress Relaxation in Tantalum Thin Films
Authors: Mutscheller A. , Clevenger L. A. , Harper J.M.E. , Cabrai C. , Barmakt K. 
Published: March 2011

AbstractWe demonstrate that the high temperature polymorphic tantalum phase transition from the tetragonal beta phase to the cubic alpha phase causes complete stress relaxation and a large decrease in the resistance of tantalum thin films. 100 nm beta tantalum thin films were deposited onto thermally oxidized <100> silicon wafers by dc magnetron sputtering with argon. In situ stress and resistance at temperature were measured during temperature-ramped annealing in purified He. Upon heating, films that were initially compressively stressed showed increasing compressive stress due to thermo-elastic deformation from 25 to 550°C, slight stress relief due to plastic deformation from 550 to 700°C and complete stress relief due to the beta to alpha phase transformation at approximately 700–800°C. Incomplete compressive stress relaxation was observed at high temperatures if the film was initially deposited in the alpha phase or if the beta phase did not completely transform into alpha by 800°C. This incomplete beta to alpha phase transition was most commonly observed on samples that had radio frequency substrate bias greater than -100 V. We conclude that the main stress relief mechanism for tantalum thin films is the beta to alpha phase transformation that occurs at 700 to 800°C.
Fracture Behavior of CVD Diamond
Authors: Drory M. D. , Gardinier J. F. , Pinneo J. M. 
Published: March 2011

ABSTRACTThe fracture behavior of CVD diamond is examined by indentation experiments in which slow crack growth has been observed. Diamond films of 400μm thickness were prepared by plasma-enhanced CVD on a silicon substrate, subsequently removed from the substrate, and polished for indentation testing. A microhardness tester was used to produce Vickers indentations under low load. Crack length measurements over time revealed susceptibility to slow crack growth in ambient testing conditions. The stress-corrosion susceptibility coefficient, N, was measured as 9.3.
Cracking in Thin Films and Substrates
Authors: Ståhle P. , Shih C. F. 
Published: March 2011

ABSTRACTA crack terminating perpendicularly at the bimaterial interface is analyzed. Stress distributions for a broad range of elastic moduli and yield strength mismatch are discussed. These results can be used to understand the effect of mechanical properties mismatch on the competition between crack deflecting into the interface and crack penetrating into the base material. The role of microdefects near the interface is explored.
Adhesion of Thin Metal Films to Vacuum-Cleaved SiO2, Al2O3, and MgO Substrates
Authors: Simanovskis Andris , Stolyarova Sara , Varchenya Silvia 
Published: March 2011

ABSTRACTThe adhesion of Au, Ag, Pb, Sn, In, Cu, Cd, Mg, Ca films to vacuum-cleaved Al2O3, MgO and SiO2 single crystals has been studied. It is shownf -4hat for botn Al2O3 and MgO the level of adhesion is slightly higher than that for SiO2 and tends to increase with chemical activity of deposited metals. As a result, the adhesion varies from the level of van der Waals forces to the level of chemical interaction.
The Origin of Stress in Co-Cr Alloy Thin Films Deposited by Magnetron Sputtering
Authors: Zhou Zhi-Feng , Fan Yu-Dian 
Published: March 2011

ABSTRACTCo-Cr alloy thin films are considered as an applicable perpendicular magnetic recording medium, and their mechanical properties such as internal stress can not be neglected. In this experiment, Co-Cr films are deposited on glass substrates by D. C planar magnetron sputtering, and the effects of film thickness, Ni-Fe underlayer as well as substrate temperature on the stress are studied respectively. The stresses are all tensile in all cases, and the stress existing at the film-substrate interface is very small. According to the above experimental results and the structure analysis of the films, the atomic peening effect produced by the rebounded working gas atoms can be negligible, and the stress is thought to originate from the film growth process but not from the inter-facial effect. Therefore, the structural defect elimination model is proposed (here the defects mainly include vacancies and grain boundaries). With this model, the origin of the tensile stress as well as the relations between the stress and the deposition conditions are explained qualitatively.
Very Thin Protective Film of Fe-Mo-B Based Hard Alloy for Curl-Free Magnetic Tape
Authors: Akiyama Setsuo , Matsushita N. , Nakagawa S. , Naoe M. 
Published: March 2011

ABSTRACTTribological troubles and tape-curling of perpendicular magnetic recording tapes are critical for their practical use. Thin films of a wear resistant and electrically conductive Fe-Mo-B based alloy were prepared on plasma-free tape substrates by the facing targets sputtering (FTS) method for applying them as protective layers in the magnetic tapes. The films were perfectly amorphous, very flexible and almost non-magnetic. The alloy targets for these films contained molybdenum atoms at a concentration as high as 24 at%. The Mo atomic weight is higher than that of working gas atoms Ar and Kr. Accordingly, not only Ar but also Kr atoms were recoiled from the target planes and then bombarded the growing layers to cause large compressive stress in the deposited films. Therefore, these protective films must be very thin to avoid tape-curling. Protective films as thin as 100 Å could largely reduce the dynamical friction coefficients of the surfaces of magnetic tapes owing to the hardness of their ceramic phase. In addition to this merit they possessed electrical resistivity as small as 1.2×10-4 Ω·cm. owing to their metallic binder phase. Consequently they are applicable as protective layers of curl-free magnetic tapes.
Electromigration Failure and Mechanical Stress in thin Film Conductors
Authors: Lloyd J. R. 
Published: March 2011

ABSTRACTThe role of mechanical stress in electromigration of thin films is reviewed and discussed. The role of stress in the driving force and the diffusivity are seen both to be important. The concept of the activation volume is discussed with regard to information available from its measurement. It is seen that void nucleation by electromigration or stress voiding is an unsolved theoretical problem.
Effects of High Temperature Process Steps on Void Size Distributions in Passivated, Narrow Aluminum Lines
Authors: Lilienfeld D. A. , Børgesen P. 
Published: March 2011

ABSTRACTNarrow Al lines were passivated at 300°C and subsequently annealed at 400°C for an hour. The passivation layer was then removed and the lines analyzed for thermal stress induced voids. Effects of the multiple high temperature process steps necessary in chip manufacturing were simulated by repeated anneals. Renewed void nucleation occurred during cool-down from each anneal, leading to a systematic increase in void density. In contrast, the maximum void size did not increase with number of anneals while it did increase with aging time for a single anneal.
Modification of The Near-Surface Region Of Al2O3 By Ion Implantation
Authors: White C. W. , Farlow G. C. , Naramoto H. , Mchargue C. J. , Appleton B. R. 
Published: March 2011

ABSTRACTPhysical and structural property changes resulting from ion implantation and thermal annealing of α-A12O3 are reviewed. Emphasis is placed on damage production during implantation, damage recovery during thermal annealing, and impurity incorporation during thermal annealing. Physical and structural property changes caused by ion implantation and annealing are correlated with changes in the mechanical properties.
Mechanical and Structural Properties of Ion Implanted Yttria Stabiizeed Zirconia Ceramics
Authors: Cochran J. K. , Legg K. O. , Solnick-Legg H. F. 
Published: March 2011

ABSTRACTSingle crystal yttria stabilized zirconia was implanted with 100 keV Ca+, Al+, and O2+ ions at fluences of 1015 to 6 × 1016 ions/cm2; . Blistering was observed at doses of 3 × 1016; O2;+ cm−2; and 6 × 1016; Al+ cm−2; but none was evident with Ca+. Knoop microhardness with a shallow indenter penetration depth peaked at a dose of 1016; ions/cm−2; for both Al+ and O2;+ but Ca+ produced no effect on microhardness. Vicker's microhardness with a much greater indenter penetration depth was not changed detectably by implantation but fracture toughness measurements from the same Vicker's indentations exhibited 10–23% increases at the highest O2+ doses and 20–25% increases at high Al+ doses. Annealing the highest implant doses at 1200° reduced the fracture toughness to pre-implant levels. Reflection electron diffraction showed that the surface had not been made amorphous by the 6 × 1016; Al+ dose as a well crystallized diffraction pattern was obtained.
The effect of substitutional H− Ions on the optical and Electrical Properties of Thermochemically-Reduced MgO and CaO
Authors: Summers G. P. , Chakrabarti K. 
Published: March 2011

ABSTRACTThermochemical reduction at high temperature of MgO and CaO single crystals introduces both anion vacancies, with absorption in the ultraviolet, and substitutional H− ions, with local mode absorptions near 1000 cm−1. The source of the hydrogen is water in the starting material. H− ions strongly influence the photoluminescence and thermoluminescence of the samples and enable F center luminescence to be excited at low temperature by low energy, E<1.8 eV, radiation. The long-lived luminescence of anion vacancies in these samples is accompanied by photoconductivity and a large dark current which increases as the concentration of H− ions increases. The activation energy for release of electrons from H= ions can be calculated from the temperature dependence of the F center luminescence decay.
Plasma

Sintering

of Ceramics
Authors: Lynn Johnson D. , Sanderson Wayne B. , Kemer Eric L. , Knowlton Jennifer 
Published: March 2011

ABSTRACTAlumina rods doped with MgO have been sintered by rapid translation through three plasma devices, namely a microwave induced plasma, a hollow cathode discharge, and an RF induction coupled plasma. Rapid densification to high density and fine grain size was observed. Some similarities and significant differences existed among the different devices.
Formation and Modification of Oxide Networks by Chemical Polymerization
Authors: Yoldas Bulent E. 
Published: March 2011

ABSTRACTThe properties of glass and ceramic materials are largely determined by the types and distribution of bonds in the network structure. Since conventional methods of forming these materials by melting or sintering do not allow significant variations from the equilibrium conditions, the properties of these materials are generally fixed by the chemical composition and crystalline structure. Synthesis of these materials by chemical polymerization at low temperatures, on the other hand, permits significant modifications to the ultrastructure. These structural modifications in turn modify the material properties, without compositional alterations. In this presentation, further studies of structure-modifying parameters are discussed.
Processing and Microstructural Characterization of TiB2 Liquid Phase Sintered with Ni and Ni3Al
Authors: Angelini P. , Becher P. F. , Bentley J. , Finch C. B. , Sklad P. S. 
Published: March 2011

ABSTRACTAn Analytical Electron Microscopy investigation of TiB2 hot-pressed and pressureless sintered with Ni revealed the presence of Ni3B and tau intergranular phase, respectively. Convergent Beam Electron Diffraction (CBED) was used for crystal structure determination and compositions were determined by quantitative x-ray Energy Dispersive Spectroscopy (EDS) and Electron Energy Loss Spectroscopy (EELS). The phase analyses were compared with phase diagram data. An evaluation was also made of TiB2 hot pressed with Ni3Al. Quantitative EDS and EELS microanalysis indicated a Ni,Al type boride tau (Cr23C6 type) intergranular phase.
Formation Mechanism of High Dense Form Boron Nitride Under Shock Compression
Authors: Sawaoka Akira , Akashi Tamotsu 
Published: March 2011

ABSTRACTThe structural changes of graphite-like boron nitride caused by multiple shock-compressions were investigated. Wurtzite type, zinc blende type, new modification and amorphous of BN induced by multiple shock-compressions were obtained. Formation mechanism of high dense form boron nitride under shock compression was discussed.
Frictional

Hot-Spots and Propellant Sensitivity
Authors: Dienes John K. 
Published: March 2011

ABSTRACTWhen propellant cylinders are fired at low speeds against a steel plate, detonations are often observed. Since the process is not repeatable, and shock heating is not significant, it is natural to consider the possibility of detonation caused by hot spots. Several mechanisms are compared, and it is suggested that interfacial friction of closed cracks seems to be the most likely mechanism.
Insulator Materials in High Power Lasers for Inertial Fusion: Present and Future
Authors: Krupke William F. 
Published: March 2011

ABSTRACTDielectric insulator materials have played a critical role in the development of high peak power solid state lasers for use in inertial confinement fusion research: as laser gain media; as transparent substrates for lenses, mirrors, and polarizers; and as active optical materials in nonlinear harmonic generators and electro-optical devices. Materials have been developed which have exceptionally high resistance to damage in the presence of intense optical beams (> GW/cm2) and which possess other properties which optimize their functions in the laser systems. Fusion lasers built to date have been designed for “single shot” operation, and the dielectric insulator materials developed for use in them have had to function under only extremely low average power loading. As we look to the future, fusion laser systems will be required to operate repetitively (few Hz) and deliver high average power output (> MW) at an efficiency greater than 10 percent. Insulator materials for use in these systems must be selected and developed on the basis of their combined mechanical, thermal, and optical properties. In this presentation, I will summarize the important characteristics of currently used insulator materials, identify figures of merit for materials needed in future systems, and outline a methodology for identifying and evaluating new materials meeting the stringent performance requirements of future fusion laser systems.
Photo-Induced Optical Switching in Mica Intercalated With Silver Compounds
Authors: Kambe N. , Yamada Tomoaki 
Published: March 2011

ABSTRACTNovel photo-induced optical phenomena observed for AgX-intercalated mica compounds are presented, where X=NO3 , Cl, Br, or I. All compounds are newly synthesized and exhibit photochromism switched by alternate illumination with 0.3∼0.4 µm and 0.7∼0.8 µm light. AgNO3 -mica furthermore yields peculiar oscillatory phenomena under continuous illumination with ∼0.8 µm light. A hypothetical mechanism for these photo-induced effects is discussed on the basis of the nonlinear excitation and relaxation processes of AgX molecules sandwitched between mica layers.
Dislocation Dissociation in MgQnAl2O3 Spinels
Authors: Wendt H. , Ostyn K. M. , Carter C. B. 
Published: March 2011

ABSTRACTThe structure of low-angle tilt boundaries in magnesium-aluminate spinel has been studied by transmission electron microscopy. Special low-angle boundaries have been prepared from bicrystals but also boundaries in polycrystalline spinels were studied. The dislocations were all dissociated into partials. Their dissociation widths were found to increase with deviation from stoichiometry. Observations at lattice dislocations indicate that the composition at the boundaries may be different from the nominal composition.
The Dependence of the Deformation of Mn1-δO; on the Deviation from Stoichiometry*
Authors: Routbort J. L. 
Published: March 2011

ABSTRACTThe stress-strain behavior of <100> single crystals of Mn1-δQ has been measured for the first time. The experiments were performed at 1200°C varying the oxygen partial pressure PO2 from 10-12 to 10-5 atms which causes the deviation from stoichiometry δ to vary between 5×10-2 to 2 percent. The upper yield stress and the stress achieved at a zero work-hardening rate vary by a factor of 2 as a function of δ and exhibit a maximum at pO2∼10-9 atms. The present results suggest that the diffusion of oxygen interstitials control deformation for large δ while oxygen vacancies control deformation for small δ, an interpretation used to explain the deformation Co1-δQ. These results illustrate the intimate relationship between defect properties and deformation in nonstoichiometric oxides.