Diffusion of Arsenic in Single Crystalline CoSi2

1995 ◽  
Vol 402 ◽  
Author(s):  
A. Pisch ◽  
J. Cardenas ◽  
B. G. Svensson ◽  
C. S. Petersson
Keyword(s):  
Diffusion Coefficient ◽  
Secondary Ion Mass Spectrometry ◽  
Lattice Diffusion ◽  
High Dose ◽  
Exponential Factor ◽  
Self Diffusion ◽  
Different Temperatures ◽  
Secondary Ion ◽  
Self Diffusion Coefficient ◽  
Different Doses

AbstractThe lattice diffusion of arsenic in CoSi2 has been studied in the temperature range from 750°C to 950°C. Two types of bulk samples were used: single crystals prepared by a modified Czochralski pulling technique from a radio frequency levitated melt and polycrystals synthesised by quenching from the melt. The latter samples were subsequently annealed in vacuum at 900°C and displayed grain sizes in the millimetre range. Starting from an ion implanted arsenic profile with two different doses (5·1014 and 5·1015 cm−2) the concentration versus depth profiles after annealing at different temperatures and different times were measured using secondary ion mass spectrometry (SIMS). Contrary to previous studies by other authors substantial diffusion has been observed with an activation energy of 3.3 eV and a pre-exponential factor of 7.37 cm2/s for the diffusion coefficient. These values are very close to the self diffusion coefficient of Si in CoSi2 suggesting that the As atoms migrate via thermal vacancies on nearest neighbour lattice sites by a similar type of mechanism as the Si (and Co) atoms. In the high dose implanted polycrystalline samples arsenic precipitation occurred which gives an estimate for the solid solubility in the 1019 atoms/cm3 range at 800 °C.

Diffusion of Nb in Nb-H Alloys

2005 ◽  
Vol 237-240 ◽  
pp. 346-351
Author(s):  
Yoshihiro Yamazaki ◽  
Takahiro Iida ◽  
Yoshiaki Iijima ◽  
Yuh Fukai
Keyword(s):  
Diffusion Coefficient ◽  
Activation Energies ◽  
The Self ◽  
Exponential Factor ◽  
Temperature Range ◽  
Self Diffusion ◽  
Diffusion Enhancement ◽  
The Difference ◽  
Self Diffusion Coefficient ◽  
Hydrogen Dissolution

Self-diffusion coefficient of 95Nb in NbHx alloys (x=0.05,0.25 and 0.3) has been determined in the temperature range from 823 to 1323 K by using a serial sputter-microsectioning technique. The self-diffusion coefficient of Nb in the NbHx alloys are larger than that in Nb, suggesting that vacancies are formed by hydrogen dissolution, that is, the formation of hydrogen-induced vacancies. The value of the pre-exponential factor for the Nb diffusion in the NbH0.05 alloy is five times larger than that in Nb, while the difference in the activation energies between the NbH0.05 alloy and pure Nb is small. The self-diffusion enhancement in the NbH0.05 alloy is mainly caused by lowering in vibrational frequencies of atoms in the immediate neighborhood of hydrogen-induced vacancies.

Self-Diffusion in Isotopically Controlled Heterostructures of Elemental and Compound Semiconductors

1998 ◽  
Vol 527 ◽  
Author(s):  
H. Bracht ◽  
E. E. Haller ◽  
K. Eberl ◽  
M. Cardona ◽  
R. Clark-Phelps
Keyword(s):  
Temperature Dependence ◽  
Diffusion Coefficients ◽  
Secondary Ion Mass Spectrometry ◽  
Activation Enthalpy ◽  
Exponential Factor ◽  
Self Diffusion ◽  
Diffusion Studies ◽  
Exponential Factors ◽  
Secondary Ion ◽  
Diffusion Profiles

ABSTRACTWe report self-diffusion studies of silicon between 855 and 1388°C in highly enriched epitaxial 28Si layers. Diffusion profiles of 30Si and 29Si are determined with high resolution secondary ion mass spectrometry (SIMS). The temperature dependence of the Si self-diffusion coefficients is accurately described with an activation enthalpy of 4.76 eV and a pre-exponential factor of 560 cm2s-1. The single activation enthalpy indicates that Si self-interstitials dominate self-diffusion over the whole temperature range investigated. Self- and interdiffusion in buried Al71GaAs/Al69GaAs/71GaAs isotope heterostructures with different Al composition is measured between 800 and 1160°C. Ga self-diffusion in AlGaAs and interdiffusion of Al and Ga at the AlGaAs/GaAs interface show that Ga diffusion decreases with increasing Al composition and that the interdiffusion coefficient depends linearly on Al concentration. Furthermore Al is found to diffuse more rapidly into GaAs than Ga diffuses in GaAs. The temperature dependence of Ga and Al diffusion in GaAs and of Ga diffusion in AlGaAs is described by a single activation enthalpy in the range of 3.6±0.1 eV, but by different pre-exponential factors. Differences found for Ga and Al diffusion in GaAs and for Ga diffusion in AlGaAs with different Al concentrations are discussed.

scholarly journals Diffusion of oxytocin in water: a molecular dynamics study

BIBECHANA ◽  
2021 ◽  
Vol 18 (1) ◽  
pp. 108-117
Author(s):  
Khimananda Acharya ◽  
Rajendra Prasad Koirala ◽  
Nurapati Pantha
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficient ◽  
Molecular System ◽  
Dynamics Simulation ◽  
Water Model ◽  
Binary Diffusion Coefficient ◽  
Self Diffusion ◽  
Different Temperatures ◽  
The Stability ◽  
Self Diffusion Coefficient

Classical molecular dynamics simulation is performed to estimate the diffusion coefficient of oxytocin in water at different temperatures, 288 K, 300 K, 313 K, 323 K, using GROningen Machine for Chemical Simulations (GROMOCS). The simulation is carried out using GROMOS43A1 force field and extended simple point charge (SPC/E) water model. The stability of the system is evaluated from energy profile of potential and kinetic energy, which assures well equilibrated molecular system. The self-diffusion coefficient of oxytocin and water is obtained from Einstein’s relation and binary diffusion coefficient is obtained from Darken’s relation. As temperature increases the diffusion coefficient also increases as per expectation. The diffusion coefficients of water from the present calculations agree well with the previously reported values, within the 10% of deviation. Furthermore, the activation energy has been studied using Arrhenius Plot. BIBECHANA 18 (2021) 108-117

Grain boundary self-diffusion in Ni: Effect of boundary inclination

2005 ◽  
Vol 20 (5) ◽  
pp. 1146-1153 ◽  
Author(s):  
Mikhail I. Mendelev ◽  
Hao Zhang ◽  
David J. Srolovitz
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Grain Boundary ◽  
Boundary Plane ◽  
The Self ◽  
High Symmetry ◽  
Exponential Factor ◽  
Self Diffusion ◽  
Arrhenius Function ◽  
Self Diffusion Coefficient

We examined the influence of the boundary plane on grain-boundary diffusion in Ni through a series of molecular dynamics simulations. A series of 〈010〉 ∑5 tilt boundaries, including several high symmetry and low symmetry boundary planes, were considered. The self-diffusion coefficient is a strong function of boundary inclination at low temperature but is almost independent of inclination at high temperature. At all temperatures, the self-diffusion coefficients are low when at least one of the two grains has a normal with low Miller indices. The grain boundary self-diffusion coefficient is an Arrhenius function of temperature. The logarithm of the pre-exponential factor in the Arrhenius expression was shown to be nearly proportional to the activation energy for diffusion. The activation energy for self-diffusion in a (103) symmetric tilt boundary is much higher than in boundaries with other inclinations. We discuss the origin of the boundary plane density–diffusion coefficient correlation.

Molecular dynamics study of diffusion of krypton in water at different temperatures

2016 ◽  
Vol 30 (11) ◽  
pp. 1650064 ◽  
Author(s):  
Dipendra Bhandari ◽  
N. P. Adhikari
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Mean Square Displacement ◽  
Mutual Diffusion ◽  
Arrhenius Behavior ◽  
Self Diffusion ◽  
Velocity Autocorrelation ◽  
Different Temperatures ◽  
Self Diffusion Coefficient

Molecular dynamics study of diffusion of two krypton atoms in 300 SPC/E water molecules at temperatures 293, 303, 313, 323 and 333 K has been carried out. Self-diffusion coefficient of krypton and water along with their mutual diffusion coefficients are estimated. Self-diffusion coefficient for krypton is calculated by using Mean Square Displacement (MSD) method and Velocity Autocorrelation (VACF) method, while that for water is calculated by using MSD method only. The mutual diffusion coefficient is estimated by using the Darken’s relation. The diffusion coefficients are found to follow the Arrhenius behavior. The structural properties of the system have been estimated by the study of solute–solute, solvent–solvent, and solute–solvent Radial Distribution Function (RDF).

scholarly journals Molecular dynamics study of diffusion of xenon in water at different temperatures

2018 ◽  
Vol 16 (2) ◽  
Author(s):  
Niraj Kumar ◽  
Narayan Prasad Adhikari
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficient ◽  
Structural Properties ◽  
The Self ◽  
Dynamics Simulation ◽  
Velocity Autocorrelation Function ◽  
Arrhenius Behavior ◽  
Self Diffusion ◽  
Different Temperatures ◽  
Self Diffusion Coefficient

Molecular Dynamics simulation was performed using 2 xenon atoms as solute and 300 water molecules as solvent. We have studied the structural properties as well as transport property. As structural properties, we have determined the radial distribution function (RDF) of xenon-xenon, xenon-water, and water-water interactions. Study of RDF of xenon-xenon and oxygen-oxygen interactions of water shows that there is hydrophobic behavior of xenon in the presence of water. We have studied the self diffusion coefficient of xenon, water, and mutual diffusion coefficients of xenon in water. The self diffusion coefficient of xenon was estimated using both mean-squared displacement (MSD) and velocity autocorrelation function (VACF), while only MSD was used for water. The temperature dependence of the diffusion coefficient of xenon and water were found to follow the Arrhenius behavior. The activation energies obtained are 12.156 KJ/mole with MSD and 14.617 KJ/mole with VACF in the temperature range taken in this study.

Temperature dependence of diffusion coefficient of nitrogen gas in water: A molecular dynamics study

2014 ◽  
Vol 28 (14) ◽  
pp. 1450084 ◽  
Author(s):  
Keshav Sharma ◽  
Narayan P. Adhikari
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficient ◽  
Structural Properties ◽  
Diffusion Coefficients ◽  
Molecular Nitrogen ◽  
Velocity Autocorrelation Function ◽  
Self Diffusion ◽  
Water Solvent ◽  
Different Temperatures ◽  
Self Diffusion Coefficient

We have carried out the molecular dynamics (MD) simulation to study the structural properties and to estimate the diffusivity of molecular nitrogen ( N 2) gas (solute) in extended simple point charge model (SPC/E) water (solvent) with N 2 mole fraction of 0.018 at different temperatures. For the structural properties of the system, we have determined radial distribution function (RDF). The solute–solute, solute–solvent and solvent–solvent RDF have been evaluated. Self-diffusion coefficient of N 2 was estimated by evaluating mean-squared displacement (MSD) and velocity autocorrelation function (VACF) separately. The diffusion coefficients obtained from the two methods agree within 3%. The results are in agreement with the experimentally determined values within 10%. The self-diffusion coefficient of water ( H 2 O ) was also estimated by evaluating MSD. Mutual diffusion coefficient of the system have also been estimated invoking Darken's relation. The temperature dependance of the diffusion coefficients were found to follow Arrhenius relation.

Towards Measuring the Pu Self-Diffusion Coefficient in Polycrystalline U0.55Pu0.45O2±x

2012 ◽  
Vol 323-325 ◽  
pp. 203-208 ◽  
Author(s):  
S. Noyau ◽  
Philippe Garcia ◽  
B. Pasquet ◽  
I. Roure ◽  
Fabienne Audubert ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Secondary Ion Mass Spectrometry ◽  
Original Method ◽  
Polished Surface ◽  
Concentration Profiles ◽  
Experimental Conditions ◽  
Self Diffusion ◽  
Tracer Atom ◽  
Self Diffusion Coefficient ◽  
Diffusion Profiles

This paper describes an original method to measure the plutonium self-diffusion coefficient in the mixed oxide U0.55Pu0.45O2±x. This method is based on using 242Pu as a tracer atom. A thin film of the tracer was deposited on the well-polished surface of the samples and then diffusion annealings were performed from 1500°C to 1700°C, in an Ar-H2 5% atmosphere. The oxygen potential was fixed at-395 kJ.mol-1. After annealing, the 242Pu self-diffusion profiles were established by means of secondary ion mass spectrometry (SIMS). The 242Pu concentration profiles were determined by assessing the relative U, Am and Pu ionisation yields according to the experimental parameters. The choice of favourable experimental conditions and the relevance of the resulting concentration profiles are discussed at length.

Oxygen self-diffusion in cerium oxide doped with Nd

2001 ◽  
Vol 16 (1) ◽  
pp. 179-184 ◽  
Author(s):  
Michiyo Kamiya ◽  
Eriko Shimada ◽  
Yasuro Ikuma ◽  
Manabu Komatsu ◽  
Hajime Haneda ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Oxygen Diffusion ◽  
Secondary Ion Mass Spectrometry ◽  
Diffusion Annealing ◽  
Exchange Coefficient ◽  
Surface Exchange ◽  
Oxygen Diffusion Coefficient ◽  
Self Diffusion ◽  
Surface Exchange Coefficient ◽  
Secondary Ion

Polycrystalline Ce0.77Nd0.23O1.885having a relative density in excess of 98% was prepared. Oxygen diffusion experiments were performed for the temperature range from 750 to 1100 °C, in an oxygen partial pressure of 6.6 kPa. The concentration profile of18O in the specimens following diffusion annealing was measured by secondary ion mass spectroscopy (SIMS). The oxygen self-diffusion coefficient obtained using secondary ion mass spectrometry was expressed by D = 6.31 × 10−9exp(−53 kJ mol−1/RT) m2s−1and was in the extrinsic region. The oxygen diffusion coefficient of Ce0.77Nd0.23O1.885was larger than that of Ce0.8Y0.2O1.90; it was close to those of Ce0.6Y0.4O1.80and Ce0.69Gd0.31O2−δ. The oxygen diffusion coefficient obtained by the tracer method at 700 °C agreed with that calculated from the electrical conductivity in Ce0.77Nd0.23O1.885. The activation energy of the surface exchange coefficient was 94 kJ mol−1, and the values of the surface exchange coefficient were similar to those of stoichiometric CeO2and ThO2.

Self-Diffusion in Intrinsic and Extrinsic Silicon Using Isotopically Pure 30Silicon Layer

2001 ◽  
Vol 669 ◽  
Author(s):  
Yukio Nakabayashi ◽  
Hirman I. Osman ◽  
Toru Segawa ◽  
Kazunari Toyonaga ◽  
Satoru Matsumoto ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Diffusion Coefficient ◽  
Temperature Dependence ◽  
Diffusion Coefficients ◽  
Secondary Ion Mass Spectrometry ◽  
Intrinsic Diffusion Coefficient ◽  
Intrinsic Diffusion ◽  
Self Diffusion ◽  
Secondary Ion ◽  
Diffusion Profiles

ABSTRACTSilicon self–diffusion coefficients were measured in intrinsic and extrinsic silicon from870 to 1070°C using isotopically pure 30Si layer. 30Si diffusion profiles are determined by secondary ion mass spectrometry. The temperature dependence of intrinsic diffusion coefficient in bulk Si isobtained. Comparing it in heavily As-doped or B-doped Si, it is found that Si self-diffusion is entirely mediated by interstitialcy mechanism at lower temperatures below 870°C.

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