Modeling of High Fluence Titanium Ion Implantation and Vacuum Carburization in Steel

1983 ◽  
Vol 27 ◽  
Author(s):  
D. Farkas ◽  
I. L. Singer ◽  
M. Rangaswamy
Keyword(s):  
Vacuum System ◽  
Time Interval ◽  
High Fluence ◽  
Saturation Point ◽  
Mixing Processes ◽  
Depth Profiles ◽  
Vacuum Carburization ◽  
Sputtering Yield ◽  
Lattice Dilation ◽  
Best Fit

ABSTRACTConcentration vs. depth profiles have been calculated for Ti and C in 52100 Ti-implanted steel. A computer formalism was developed to account for diffusion and mixing processes, as well as sputtering and lattice dilation. A Gaussian distribution of Ti was assumed to be incorporated at each time interval. The effects of sputtering and lattice dilation were then included by means of an appropriate coordinate transformation. C was assumed to be gettered from the vacuum system in a one-to-one ratio with the surface Ti concentration up to a saturation point. Both Ti and C were allowed to diffuse. A series of experimental (Auger) concentration vs. depth profiles of Ti implanted steel were analyzed using the above-mentioned assumptions. A best fit procedure for these curves yielded information on the values of the sputtering yield, range and straggling, as well as the mixing processes that occur during the implantation. The observed values are in excellent agreement with the values predicted by existing theories.

Nitrogen and Carbon Solute Redistribution During High Fluence Nitrogen Implantation into Iron

1988 ◽  
Vol 100 ◽  
Author(s):  
P. D. Ehni ◽  
I. L. Singer ◽  
S. M. Hues
Keyword(s):  
Mass Spectroscopy ◽  
Iron Nitrides ◽  
High Fluence ◽  
Solute Redistribution ◽  
Nitrogen Implantation ◽  
Depth Profiles ◽  
High Fluences ◽  
Distribution Studies ◽  
Lattice Dilation ◽  
Secondary Ion

ABSTRACTModel solute distribution studies have been performed in N-implanted Fe. Concentration-verses-depth profiles have been determined by secondary ion mass spectroscopy for Fe implanted to low fluences with isotopes 13C at 190keV and 15N at 180keV followed by 14N to high fluences. At N fluences greater than 2.5 × 1017 /cm2 dramatic changes in the 13C and 15N profiles are observed. It is proposed that these changes are caused by the lattice dilation due to precipitation of iron nitrides.

Preparation of Backthinned Ceramic Specimens

1985 ◽  
Vol 43 ◽  
pp. 182-183
Author(s):  
A. T. Fisher ◽  
P. Angelini
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Vacuum System ◽  
Back Surface ◽  
Surface Microstructure ◽  
Ion Milling ◽  
Near Surface ◽  
Depth Profiles ◽  
Analytical Electron ◽  
Ion Implanted

Analytical electron microscopy (AEM) of the near surface microstructure of ion implanted ceramics can provide much information about these materials. Backthinning of specimens results in relatively large thin areas for analysis of precipitates, voids, dislocations, depth profiles of implanted species and other features. One of the most critical stages in the backthinning process is the ion milling procedure. Material sputtered during ion milling can redeposit on the back surface thereby contaminating the specimen with impurities such as Fe, Cr, Ni, Mo, Si, etc. These impurities may originate from the specimen, specimen platform and clamping plates, vacuum system, and other components. The contamination may take the form of discrete particles or continuous films [Fig. 1] and compromises many of the compositional and microstructural analyses. A method is being developed to protect the implanted surface by coating it with NaCl prior to backthinning. Impurities which deposit on the continuous NaCl film during ion milling are removed by immersing the specimen in water and floating the contaminants from the specimen as the salt dissolves.

Stoichiometric Disturbance in InP Measured During Ion Implantation Process

1983 ◽  
Vol 27 ◽  
Author(s):  
D. Haberland ◽  
P. Harde ◽  
H. Nelkowski ◽  
W. Schlaak
Keyword(s):  
Quantitative Analysis ◽  
Ion Implantation ◽  
Target Chamber ◽  
Depth Profiles ◽  
Preferential Sputtering ◽  
Implantation Process ◽  
Sputtering Yield ◽  
Set Up

ABSTRACTTo measure the sputtered ions during implantation a specially designed UHV-target chamber with a SIMS apparatus was set up. Quantitative analysis are possible with an Auger spectrometer. Disturbances in the stoichiometry in InP are measured during implantation of Sn. The enrichment of the doped surface of InP with the lighter component phoshorus will be discussed in consideration of preferential sputtering and recoil effects during implantation. Measured depth profiles of Sn in InP will be compared with calculated distributions on condition that sputtering takes place. The sputtering yield of InP bombarded by 120 keV Sn+ is 17±5.

scholarly journals Recurrent frequency-size distribution of characteristic events

2009 ◽  
Vol 16 (2) ◽  
pp. 333-350 ◽  
Author(s):  
S. G. Abaimov ◽  
K. F. Tiampo ◽  
D. L. Turcotte ◽  
J. B. Rundle
Keyword(s):  
Weibull Distribution ◽  
Passage Time ◽  
Time Interval ◽  
Weibull Distributions ◽  
Event Sequences ◽  
San Andreas ◽  
Statistical Frequency ◽  
Earthquake Sequences ◽  
Best Fit ◽  
Frequency Magnitude

Abstract. Statistical frequency-size (frequency-magnitude) properties of earthquake occurrence play an important role in seismic hazard assessments. The behavior of earthquakes is represented by two different statistics: interoccurrent behavior in a region and recurrent behavior at a given point on a fault (or at a given fault). The interoccurrent frequency-size behavior has been investigated by many authors and generally obeys the power-law Gutenberg-Richter distribution to a good approximation. It is expected that the recurrent frequency-size behavior should obey different statistics. However, this problem has received little attention because historic earthquake sequences do not contain enough events to reconstruct the necessary statistics. To overcome this lack of data, this paper investigates the recurrent frequency-size behavior for several problems. First, the sequences of creep events on a creeping section of the San Andreas fault are investigated. The applicability of the Brownian passage-time, lognormal, and Weibull distributions to the recurrent frequency-size statistics of slip events is tested and the Weibull distribution is found to be the best-fit distribution. To verify this result the behaviors of numerical slider-block and sand-pile models are investigated and the Weibull distribution is confirmed as the applicable distribution for these models as well. Exponents β of the best-fit Weibull distributions for the observed creep event sequences and for the slider-block model are found to have similar values ranging from 1.6 to 2.2 with the corresponding aperiodicities CV of the applied distribution ranging from 0.47 to 0.64. We also note similarities between recurrent time-interval statistics and recurrent frequency-size statistics.

scholarly journals Geochemical Modeling of Iron and Aluminum Precipitation during Mixing and Neutralization of Acid Mine Drainage

Minerals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 547 ◽  
Author(s):  
Darrell Kirk Nordstrom
Keyword(s):  
Acid Mine Drainage ◽  
Mine Drainage ◽  
Geochemical Modeling ◽  
Lime Treatment ◽  
Mixing Processes ◽  
Ph Values ◽  
Acid Mine ◽  
Water Composition ◽  
Slaked Lime ◽  
Best Fit

Geochemical modeling of precipitation reactions in the complex matrix of acid mine drainage is fundamental to understanding natural attenuation, lime treatment, and treatment procedures that separate constituents for potential reuse or recycling. The three main dissolved constituents in acid mine drainage are iron, aluminum, and sulfate. During the neutralization of acid mine drainage (AMD) by mixing with clean tributaries or by titration with a base such as sodium hydroxide or slaked lime, Ca(OH)2, iron precipitates at pH values of 2–3 if oxidized and aluminum precipitates at pH values of 4–5 and both processes buffer the pH during precipitation. Mixing processes were simulated using the ion-association model in the PHREEQC code. The results are sensitive to the solubility product constant (Ksp) used for the precipitating phases. A field example with data on discharge and water composition of AMD before and after mixing along with massive precipitation of an aluminum phase is simulated and shows that there is an optimal Ksp to give the best fit to the measured data. Best fit is defined when the predicted water composition after mixing and precipitation matches most closely the measured water chemistry. Slight adjustment to the proportion of stream discharges does not give a better fit.

scholarly journals Depth profiles of nitrogen implanted into zirconium at high fluence.

1997 ◽  
Vol 46 (7) ◽  
pp. 549-553
Author(s):  
Seita TANEMURA ◽  
Yoshiko MIYAGAWA ◽  
Soji MIYAGAWA
Keyword(s):  
High Fluence ◽  
Depth Profiles

scholarly journals ENDOTHERMY AND TEMPERATURE REGULATION IN BEES: A CRITIQUE OF ‘GRAB AND STAB’ MEASUREMENT OF BODY TEMPERATURE

1989 ◽  
Vol 143 (1) ◽  
pp. 211-223 ◽  
Author(s):  
G. N. STONE ◽  
P. G. WILLMER
Keyword(s):  
Body Temperature ◽  
Ambient Temperature ◽  
Laboratory Experiments ◽  
Passive Cooling ◽  
Time Interval ◽  
Body Temperatures ◽  
Warm Up ◽  
Tethered Flight ◽  
The Relationship ◽  
Best Fit

‘Grab and stab’ methods have become standard in the measurement of insect body temperatures. The gradient of the best-fit regression of body temperature on ambient temperature is often used as a measure of the thermoregulatory ability of a species. The temperatures recorded are commonly accepted as slight underestimates of actual values prior to capture due to passive cooling between capture and insertion of the thermocouple. Here we present laboratory experiments involving tethered flight which show that bees often warm up on cessation of flight, and that errors due to warm-up over the time interval typically associated with ‘grab and stab’ sampling may be significant. More importantly, the errors due to warm-up in two species are shown to change with ambient temperature, thus affecting the form of the relationship between ambient and body temperatures. We compare laboratory and field data to illustrate the way in which warm-up errors may exaggerate apparent thermoregulatory ability, and we urge greater caution in the interpretation of ‘grab and stab’ data.

scholarly journals Modeling of high fluence Ti ion implantation and vacuum carburization in steel

1985 ◽  
Vol 57 (4) ◽  
pp. 1114-1120 ◽  
Author(s):  
D. Farkas ◽  
I. L. Singer ◽  
M. Rangaswamy
Keyword(s):  
Ion Implantation ◽  
High Fluence ◽  
Vacuum Carburization

Explaining Scales and Statistics of Tropical Precipitation Clusters with a Stochastic Model

2019 ◽  
Vol 76 (10) ◽  
pp. 3063-3087 ◽  
Author(s):  
Fiaz Ahmed ◽  
J. David Neelin
Keyword(s):  
Stochastic Model ◽  
Power Law ◽  
Cluster Size ◽  
Mixing Efficiency ◽  
Model Parameters ◽  
Time Interval ◽  
Multiple Model ◽  
Mixing Processes ◽  
Probability Metric ◽  
Lateral Mixing

Abstract Precipitation clusters are contiguous raining regions characterized by a precipitation threshold, size, and the total rainfall contained within—termed the cluster power. Tropical observations suggest that the probability distributions of both cluster size and power contain a power-law range (with slope ~ −1.5) bounded by a large-event “cutoff.” Events with values beyond the cutoff signify large, powerful clusters and represent extreme events. A two-dimensional stochastic model is introduced to reproduce the observed cluster distributions, including the slope and the cutoff. The model is equipped with coupled moisture and weak temperature gradient (WTG) energy equations, empirically motivated precipitation parameterization, temporally persistent noise, and lateral mixing processes, all of which collectively shape the model cluster distributions. Moisture–radiative feedbacks aid clustering, but excessively strong feedbacks push the model into a self-aggregating regime. The power-law slope is stable in a realistic parameter range. The cutoff is sensitive to multiple model parameters including the stochastic forcing amplitude, the threshold moisture value that triggers precipitation, and the lateral mixing efficiency. Among the candidates for simple analogs of precipitation clustering, percolation models are ruled out as unsatisfactory, but the stochastic branching process proves useful in formulating a neighbor probability metric. This metric measures the average number of nearest neighbors that a precipitating entity can spawn per time interval and captures the cutoff parameter sensitivity for both cluster size and power. The results here suggest that the clustering tendency and the horizontal scale limiting large tropical precipitating systems arise from aggregate effects of multiple moist processes, which are encapsulated in the neighbor probability metric.

Characteristics of Ultra Shallow B Implantation with Decaborane

2002 ◽  
Vol 745 ◽  
Author(s):  
Cheng Li ◽  
Maria A. Albano ◽  
Leszek Gladczuk ◽  
Marek Sosnowski
Keyword(s):  
Cluster Ions ◽  
Smoothing Effect ◽  
Crystalline Materials ◽  
Force Microscopy ◽  
Depth Profiles ◽  
Atomic Force ◽  
Before And After ◽  
Sputtering Yield ◽  
Amorphous Si ◽  
Different Parts

ABSTRACTThe characteristics of ultra shallow B implantation with mass-analyzed decaborane cluster ions (B10Hx+) are presented. Depth profiles of B and co-implanted H were measured by SIMS, before and after annealing. Annealing results in the increase in the depth of B distribution, due to diffusion, but most of H diffuses out of Si. While the sputtering yield of Si per incoming B in a cluster was found to be comparable to the estimated sputtering yield of Si with B+ ions of the equivalent energy (∼ 1.2 keV), the surface effects of the two types of ions may be quite different. Atomic force microscopy revealed that the smoothing effect of the small decaborane cluster ions, observed previously by us on a surface of amorphous Si, is also present on crystalline Si and even on a much rougher surface of polycrystalline Ta film. The smoothing affects different parts of the power density spectra as functions of spatial frequency in the amorphous and crystalline materials. The smoothing on c-Si surfaces is in sharp contrast to roughening of these surfaces by irradiation with monomer Ar ions, which was done for reference. This indicates that different ion-surface interaction mechanisms are needed to describe impacts of cluster and of monomer ions. All other effects of Si implantation with B10Hx+ measured to date were found to be the same as those with B+ ions of equivalent energy and dose, which confirms that decaborane implantation is an alternative to the very low energy B implantation for ultra shallow p-type junctions in Si devices.

Sign in / Sign up

Export Citation Format

Share Document