bluuebunny/crossref_metadata_2025_split huggingface dataset:
The difference in kinematics of horses walking, trotting and cantering on a flat and banked 10 m circle
Authors: HOBBS S. J. , LICKA T. , POLMAN R. 
Published: March 2011

SummaryReasons for performing study:Locomotion adaptation mechanisms have been observed in horses, but little information is available in relation to banked and nonbanked curve locomotion, which might be important to optimise training environments.Objectives:To determine if adaptation mechanisms in horses existed when moving on a banked compared to a flat curve and whether adaptation was similar in different gaits.Methods:Eight infrared cameras were positioned on the outside of a 10 m lungeing circle and calibrated. Retroreflective markers were used to define left and right metacarpus (McIII) and proximal phalanges (P1), metatarsus (MtIII), head and sacrum. Data were recorded at 308 Hz from 6 horses lunged at walk, trot and canter on a flat and 10° banked circle in a crossover design. Measurements extracted were speed, stride length, McIII inclination, MtIII inclination, relative body inclination and duty factor. Data were smoothed with a fourth order Butterworth filter with 30 Hz cut‐off. ANOVA was used to determine differences between conditions and limbs.Results:Adaptation mechanisms were influenced by gait. At canter inside forelimb duty factor was significantly longer (P<0.05) on a flat curve compared to a banked curve; at walk this was reversed. McIII inclination, MtIII inclination and relative body inclination were significantly greater (P<0.05) at trot and canter on a flat curve, so more inward tilt was found relative to the bearing surface.Conclusion:Adaptation to curved motion is gait specific. At faster gaits it appears that horses negotiate a banked curve with limb posture closer to body posture and probably with demands on the musculoskeletal system more similar to straight canter.
Amorphization and Recrystallization in MeV Ion Implanted InP Crystals
Authors: Xiong Fulin , Nieh C. W. , Jamieson D. N. , Vreeland T. , Tombrello T. A. 
Published: March 2011

ABSTRACTA comprehensive study of MeV-15N-ion-implanted InP by a variety of analytical techniques has revealed the physical processes involved in MeV ion implantation into III-V compound semiconductors as well as the influence of post-implantation annealing. It provides a coherent picture of implant distribution, structural transition, crystalline damage, and lattice strain in InP crystals induced by ion implantation and thermal annealing. The experimental results from the different measurements are summarized in this report. Mechanisms of amorphization by implantation and recrystallization through annealing in MeV-ion-implanted InP are proposed and discussed in light of the results obtained.
Crystallization, Diffusion and Phase Separation in Sapphire Amorphised by Indium Ion Implantation
Authors: Cao D. X. , Sood D. K. , Pogany A. P. 
Published: March 2011

ABSTRACTIndium implantation into a-axis sapphire to peak concentrations of 8–45 mol % In produces amorphous surface layers.Migration of In during isothermal annealing at 600°C shows a strong ion dose dependence. For a dose of 6×1016In/cm2, two distinct types of In migration are seen - a) rapid diffusion of In within amorphous Al2O3 and b) diffusion of In into crystalline Al2O3 underlying the amorphous layer. For doses lower than 3×1016In/cm2 , no such migration of In is seen under identical anneal conditions. However, In undergoes phase separation into crystalline In2O3 particles embedded in amorphous Al2O3 at all doses.
Incongruent Sputtering in Nio(100) and CoO(100) with 2 keV Argon Ions
Authors: Langell M. A. , Colbert L. S. 
Published: March 2011

ABSTRACTAlthough NiO(100) sputters congruently at 300 K under 2 keV argon ion flux, sputter reduction is observed above a substrate threshold of 350 K. The reduction kinetics are described quantitatively by Fickian diffusion of subsurface oxygen coupled to differential sputtering at the sample surface. Two additional surface oxygen species are detected on sputter reduced NiO by XPS and these species have not been found on either stoichiometric or chemically reduced NiO(100).CoO(100) also shows sputter reduction, although only surfaces that have been pre-annealed to 973 K show significant reduction. Under these conditions, an epitaxial layer of Co3 O4 forms on the CoO substrate and this layer has a threshold temperature to sputter reduction of 550 K. Reduction kinetics for the epitaxy appear similar to those of NiO(100).
The Formation of Metal Carbide Layers by Elevated-Temperature Ion Implantation of Fe-Based Alloys
Authors: Sprague J. A. , Singer I. L. 
Published: March 2011

ABSTRACTAn Fe-i % C alloy has been implanted at approximately 600 °C with V to a fluence of 5 × 1017 ions/cm2 and with Nb to a fluence of 3 × 1017 ions/cm2. For both implantations, Auger analysis showed that a nominally stoichiometric metal carbide layer formed beneath the surface. Below this layer, which was depleted of Fe, the metal carbide concentration decreased gradually, giving a continually graded interface with the bulk. TEM analysis showed a continuous layer of fine-grained VC or NbC, which displayed a preferred Baker-Nutting orientation relation with the underlying a-Fe matrix.
Ion Beam Modification of Glassy Carbon
Authors: Wielunski Leszek S. , Pollock John T.A. , Farrelly Matthew 
Published: March 2011

ABSTRACTImplanted glassy carbon (GC; 50 keV, 1016 N+ cm-2) is reported to be 400 times more wear-resistant to 1 μm diamond polishing than unimplanted GC. A number of samples were implanted with 15N to produce the modified surface layer and to allow a very high sensitivity measurement of wear, using the 15N(p, α)12C nuclear reaction.Optical interferometric wear measurements are also reported. Samples implanted with 1 MeV N to 1015 ions cm-2 indicated that the enhanced wear-resistance is correlated with the nuclear energy loss density within the ion range. Mechanisms likely to be responsible for the enhanced wear resistance are also discussed.
Temperature Dependence of Kr Precipitation in Ni
Authors: Birtcher R. C. , Liu A. S. 
Published: March 2011

ABSTRACTThe precipitation of Kr injected into Ni at temperatures between 25 and 560 C has been studied with transmission electron microscopy. The Kr precipitates in cavities which increase in size with Kr fluence. Electron diffraction and dark-field imaging demonstrate that small Kr precipitates are solid, fcc crystals aligned with each other and the Ni lattice. The Kr is held in the solid state by the pressure generated by the cavity walls, and this pressure decreases with increasing cavity size. The mismatch between the Kr and Ni lattices is as large as 55%. The average Kr lattice parameter, determined from electron diffraction at room temperature, increases with increasing Kr fluence from 0.515 nm to an asymptotic value of about 0.545 nm for implantations at temperatures of 300 C or less. This increase towards an asymptotic limit is due to expansion of the Kr lattices as precipitates grow, until the decrease in cavity pressures allows melting of solid Kr in large cavities. Diffuse electron scattering was observed from liquid Kr in large precipitates for fluences greater than 5·1020Kr+m−2. Implantations at temperatures of 400 C or higher result in a bi-modal size distribution containing small solid precipitates and an additional population of larger, faceted precipitates, a larger average Kr lattice parameter for a given Kr fluence, and a higher asymptotic lattice parameter of 0.550 nm. Solid Kr seems to inhibit motion of small precipitates, and Kr melting is a precursor to faceting and growth by coalescence.
On the Trapping and Thermal Release of Low Energy Noble Gases Implanted into Silicon
Authors: Veen A. Van , Jong P. C. De , Bijkerk K. R. , Filius H. A. , Evans J. H. 
Published: March 2011

ABSTRACTGas desorption spectrometry has been used to study the behavior of implanted noble gas ions in silicon. Results of low dose Ar implants followed by thermal desorption has shown the release of argon in Si from distinct surface related trapping sites, from substitutional argon (ArV) and from larger Ar-V clusters. This information gives an insight into the response of the silicon lattice to the Ar implants. For higher Ar doses, the effects of amorphization are clear in the desorption spectra and lead tò a method of measuring the recrystallization velocity during epitaxial regrowth (v=2×106 exp(−2.8 eV/kT). A similar value was found for thin sputtered Si films. The paper discusses high dose Ar saturation phenomena and describes the use of helium implants to probe defects and defect structures, such as bubbles and voids, in silicon.
Crystallographic Aspects of Low Energy Boron Implantation Into Silicon
Authors: Lever R. F. , Brannon K. W. 
Published: March 2011

ABSTRACTThe computer program MARLOWE has been used to investigate low energy boron implantation into silicon. When implanted in a “random” direction at 5 keV, the most deeply penetrating ions are seen to have spent an appreciable part of their path travelling in <001>, <011> or <112> axial directions or in {111} or {220} planar channels. Channeling was then investigated more directly by observing the mean path travelled by the ions in the direction of incidence as a function of both azimuthal and tilt angles between the direction of incidence and the 001 direction. At 5 keV, {111} planar channeling and <110>, <112>, <111> and <100> axial channeling is prominent, with {220} planar and <310> and <114> axial channeling observed to a lesser degree. Higher order planar channeling such as {400}, {331}, {422} or (511} was not observed at 5 keV. At 0.75 keV only <110>. <100> and <112> axial channeling and {111} planar channeling remained.
Rutherford Backscattering Spectrometry Analysis of Shallow Sb-Implanted Si
Authors: Ridgway Mark C. , Whitton J. L. , Scanlon P. J. , Naem A. A. 
Published: March 2011

ABSTRACTRapid thermal annealing (RTA) of shallow Sb-implanted Si has been studied with Rutherford Backscattering Spectrometry (RBS). Single crystal Si wafers were implanted with Sb at energies of 16, 32 and 48 keV and doses of 5×1014 and 1×1015/cm2. RTA and reference furnace anneals in a nitrogen atmosphere were done to activate the dopant and remove implantation damage. Glancing-angle RBS measurements were used to determine the Sb depth distributions. Dopant profiles obtained with RBS analysis were compared with Secondary Ion Mass Spectrometry results and TRIM code calculations. RBS measurements of the projected range and range straggle did not differ significantly from TRIM code calculations. Following annealing, significant Sb diffusion from the as-implanted peak was apparent. Sb accumulation at the substrate surface was pronounced, especially for furnace-annealed samples.
Mechanisms and Kinetics of Iion Beam-Induced Compositional Modifications
Authors: Lam N. Q. 
Published: March 2011

ABSTRACTNear-surface compositional modification of ion-bombarded alloys results from the dynamic interplay of several atomistic processes. In addition to displacement mixing leading to t randomization of atomic locations, which is dominant at relatively low temperatures, and preferential loss of alloying elements by sputtering, many thermally-activated processes, including radiation-enhanced diffusion, radiation-induced segregation and Gibbsian adsorption, also play important roles. The relative contributions of these processes to the evolution of the target composition profile depends on the target materials and irradiation variables. Although a good understanding of the individual processes has been achieved, information regarding their synergistic effects on alloy surface modification is still limited. In the present article, these processes will be characterized in simple physical terms, and the present understanding of their relative significance and contributions in changing the target composition during ion bombardment will be discussed in view of recent progress in theoretical modeling and experimental study.
Study of Boron Implantation in CdTe
Authors: Jamieson D. N. , Bowman R. C. , Adams P. M. , Knudsen J. F. , Downing R. G. 
Published: March 2011

ABSTRACTThe effect of large dose boron implantation in single crystal CdTe has been investigated by Rutherford Backscattering Spectrometry with channeling (RBS), double crystal x-ray diffraction (DCD) and photoreflectance spectroscopy (PR). Comparisons are made with the results of identical B implantations of Si and GaAs crystals. Multiple energy implantations were performed at room temperature and liquid nitrogen temperature with total doses up to 1.5×1016 B+ ions/cm2. The implanted B distribution was measured with neutron depth profiling (NDP) and found to agree well with Monte-Carlo ion range calculations. The RBS results showed that the CdTe crystals had not been rendered completely amorphous even for the highest dose implantation, unlike GaAs and Si. Furthermore, the DCD results showed little implantation induced structure in the rocking curves from the implanted CdTe crystals, in contrast to GaAs. The consequences of annealing at 500°C in an attempt to regrow the crystal structure are also discussed.
Channeling Investigation of the Lattice Location of Ti in Ti-Implanted Optical Waveguides in LiNbO3
Authors: Buchal Ch. , Mantl S. , Thomas D. K. 
Published: March 2011

ABSTRACTIon channeling of 3 MeV He ions has been employed to investigate the lattice location of Ti in Ti implanted optical waveguides in LiNbO3 after Solid Phase Epitaxy. Particle-Induced X-rays (PIXE) from Ti at 4.5 keY (K∝) and Nb at 2.2 keV (L∝β) and 16.6 keV (K∝) have been detected and analyzed simultaneously.All scans yield similar behaviour of the Ti and the Nb signals. This provides clear evidence, that within well annealed implanted waveguides the Ti4+ and the Nb5+ ions occupy equivalent lattice positions.
Photoluminescence Spectra of C+-Implanted GaAs: Experimental Verification on Amphoteric Features of Carbon Impurities in GaAs
Authors: Makita Yunosuke , Shigetomi Shigeru , Mori Masahiko , Ohnishi Nobukazu , Phelan Paul , Matsumori Tokue 
Published: March 2011

ABSTRACTC+ ion-implantation was carried out for extremely pure GaAs gown by moleplar Ieam epitaxy. The dose was very widely varied from 1×1015 to 1×1020 cm−3. Photoluminescence and Raman scattering measurements were performed at 2 K and room temperature, respectively, both as functions of dose and annealing temperature. The results revealed that for a dose less than 5×1017 cm−3, where the dominant damages are point defects, annealing at 200°C is sufficient to attain a damage-free lattice. When the dose is above that value, where the principal damage is a highly disordered lattice, annealing, at least above 550°C, is required. Photoluminescence spectra showed that the well-defined near-band-gap emission, [g-g], (exclusively inherent to acceptors), was a dominant emission in the above mentioned low dose region, but was strongly suppressed in the higher region. These observations indicate that ion-implanted C atoms in GaAs behave as amphoteric impurities when the dose exceeds a critical value, of around 5×1017 cm−3.
Transition State Model for Grain Boundary Motion During Ion Bombardment
Authors: Atwater Harry A. , Thompsonm Carl V. , Smith Henry I. 
Published: March 2011

ABSTRACTIon bombardment of polycrystalline Ge, Si, and Au films leads to rates of grain boundary motion that greatly exceed rates of thermally-induced motion at the same temperature and which exhibit a weak temperature dependence. The enhanced migration rate is proportional to the rate of energy deposition in nuclear collisions at or very near the grain boundary. Experimental work is reviewed, and a transition state model is presented which accounts for the observed kinetics of grain boundary migration during bombardment. This model suggests that the rate limiting step in grain boundary motion may be thermally-induced migration of a bombardment-generated defect across the boundary. Also, the ratio of atomic jumps at grain boundaries to the local collision-induced Frenkel defect generation rate is shown to be characteristic of each material, but independent of ion mass and ion flux. The model is extended to the motion of an interface between two phases, and applications to crystallization during ion bombardment are discussed.
Ion Irradiation Induced Grain Growth in Metal Thin Films
Authors: Liu Joyce. C. , Mayer J. W. 
Published: March 2011

ABSTRACTThe dependence of ion irradiation induced grain growth on collision and material properties were studied in metal and alloy thin films. The uniform grain size increased with ion dose in the low dose regime; and the growth saturated in the high dose regime. The saturated grain size was determined 'by the cascade dimension as well as the atomic mobility. The growth was further influenced by the temperature, composition and impurity.
Amorphization of Silicon by Ion Irradiation: The Role of the Divacancy
Authors: Elliman R. G. , Linnros J. , Brown W. L. 
Published: March 2011

ABSTRACTFixed fluence ion irradiation of silicon is shown to produce either defected crystal or amorphous silicon depending on the ion flux employed. The amorphous threshold flux, defined as the minimum flux required to generate a continuous amorphous layer for a fixed fluence irradiation, is measured as a function of irradiation temperature. This critical flux for amorphization is shown to satisfy an Arrhenius expression with a unique activation energy of ∼1.2eV, which corresponds to the migration/dissociation energy of the silicon divacancy. These observations lead to the conclusion that the stability of the silicon divacancy controls the competition between defect production and dynamic defect annealing, and hence the crystalline to amorphous phase transformation.
Pulsed Ion Beam Induced Crystallization and Amorphization of Silicon
Authors: Linnros Jan , Brown W. L. , Elliman R. G. 
Published: March 2011

ABSTRACTThe ion-bombardment-induced movement of an amorphous/crystalline interface in silicon has been studied under pulsed beam conditions. Irradiations were performed with a 1.5 MeV Xe beam at temperatures of 200–300°C which induced a planar motion of the interface, either to epitaxially crystallize the amorphous material or to planar amorphize the crystalline material. It is found that at a fixed peak and average beam current the result of pulsed irradiation can vary from amorphization at low pulse repetition frequency to crystallization at high pulse repetition frequency. The frequency which characterizes this change in behavior is virtually temperature independent but strongly dependent on peak beam flux.
Segregation and Trapping of Gold During Ion-Induced Crystallization of Amorphous Si
Authors: Poate J. M. , Linnros J. , Priolo F. , Jacobson D. C. , Batstone J. L. , Thompson M. O. 
Published: March 2011

ABSTRACTA novel regime of crystal growth and segregation has been observed. Amorphous Si layers were uniformly doped with Au and epitaxial crystallization was induced in the temperature range 250–420°C using 2.5 MeV Ar ion irradiation. The Au segregation at the amorphous/crystal interface is analogous to behavior at liquid/solid interfaces except that the interfacial segregation coefficient of 0.007 at 320°C is independent of velocity between 0.6 and 6A/sec. This process results in the trapping of Au in crystalline Si at concentrations some ten orders of magnitude in excess of equilibrium concentration.
Amorphous to Polycrystalline Transformation in High Dose Ion Implanted Silicon
Authors: Nygren E. , Mccallum J. C. , Thornton R. , Williams J. S. , Olson G. L. 
Published: March 2011

ABSTRACTThe amorphous to polycrystalline transformation of silicon implanted with high doses of In, Bi, Ga, and Sn is investigated. Each of these elements forms a low temperature eutectic with crystalline silicon and the details of the phase transformations in these systems are found to be very similar. A general model for the transformation based on the nature of the binary solutions is presented.
Precipitation, Phase Transformation, and Enhanced Diffusion in Ion-Implanted Silicon
Authors: Pennycook S. J. , Culbertson R. J. , Berger S. D. 
Published: March 2011

ABSTRACTZ-contrast scanning transmission electron microscopy has been used to study the connection between dopant precipitation and phase transformation in high dose In+ and Sb+ implanted Si. In the case of In, the observations confirm a heterogeneous nucleation model. Images of the precursor precipitates give the first measurement of the diffusion coefficient in amorphous Si, with an enhancement of 107 over tracer crystalline values. With Sb+ implants enhanced homogeneous nucleation is observed. The connection between these results and the transient enhanced diffusion observed in crystallized Si is discussed.
Time-Resolved Reflectivity Measurement of the Pressure-Enhanced Crystallization Rate of Amorphous Si in a Diamond Anvil Cell
Authors: Lu G. Q. , Nygren E. , Aziz M. J. , Turnbull D. , White C. W. 
Published: March 2011

ABSTRACTWe have measured the pressure dependence of the solid phase epitaxial growth (SPEG) rate of self-implanted Si (100) by using the in-situ time-resolved reflectivity technique [1] in a hightemperature and high-pressure diamond anvil cell (DAC). With fluid argon as the pressure transmission medium, a clean and perfectly hydrostatic pressure environment is achieved around the sample. The external heating geometry employed in the DAC provides a uniform temperature across the sample. At temperatures in the range of 530 – 550 °C and pressure up to 50 kbars (5 GPa), the growth rate is enhanced by up to a factor of ten over that at 1 atmosphere pressure. The results are characterized by a negative activation volume of approximately −3.0 cm3/mole (−27% of the atomic volume). These preliminary results show a significantly weaker pressure dependence than does the previous work of Nygren et al. [2], who found an activation volume of −8.7 cm3/mole. The implications of these results for the nature of the defect responsible for thermal SPEG and irradiation enhanced SPEG is discussed.
Picosecond Laser Induced Melting: The Dielectric Function of Molten Silicon and Superheating in the Liquid Phase
Authors: Fauchet P. M. , Li K. D. 
Published: March 2011

ABSTRACTThe complex dielectric function of molten silicon produced after picosecond illumination is found to be well described by a Drude model from 1.1 eV to 3.5 eV. Close to the melting temperature, we obtain ωp = 2.50 1016rad/s and τ = 212 10−18s. Transiently, the liquid temperature can exceed the melting temperature or even the boiling temperature Tb. We observe this transient heating and model it with a relatively simple computer code which includes superheating of the liquid above Tb. These measurements are possible thanks to a novel pump and probe technique.
Nanosecond Resolved Temperature Measurements Following Pulsed Laser Irradiation
Authors: Thompson Michael O. 
Published: March 2011

ABSTRACTA transient resistance technique has been developed which allows monitoring the temperature of a thin film sample at a fixed depth from the surface following pulsed laser irradiation. The technique utilizes the temperature dependence of a thin, electrically insulated, semiconducting or metallic layer. Temperature determinations with nanosecond resolution, an absolute accuracy of ±50 K, and a relative accuracy of ±5 K are demonstrated. Combined with simultaneous interface position and velocity measurements, the undercooling at the interface during rapid solidification may be obtained. Preliminary results using this technique during the solidification of thin Ge films are presented.
Computer Simulation of Laser-Induced Ultrarapid Phase Changes
Authors: Maclin Myron T. , Sabochick Michael J. , Mills James P. 
Published: March 2011

ABSTRACTThe results of a molecular dynamics study of phase change in a system of condensed Lennard-Jones atoms is presented. These molecular dynamics results are compared to the rates of phase change predicted by two analytical phase change models. Both analytical models are supported by the molecular dynamics results.