Jul 22, 2007 airomate translations right click on download and choose save target as. Diffusing uphill with james clerk maxwell and josef stefan. During the entry of glucose into the human red cell there is an induced outward transport of radioglucose against its concentration gradient1. Incomplete homogenization of the steel sometimes increases the chemical and structural heterogeneity. Boron uphill diffusion during ultrashallow junction formation article pdf available in applied physics letters 8221. Uphill diffusion of ru was evident in the diffusion zone of the nireruniru couples under all annealing conditions despite the absence of a ru concentration gradient. Ficks law for diffusion gradients, other than concentration, can lead to hydrogen diffusion even against a concentration gradient, known as uphill hydrogen diffusion j. Ficks laws implicitly assume that the concentration gradient is the driving force for diffusion. Biological ion pumps with active ionic transport properties lay the foundation for many life processes. Atomic mobilities, uphill diffusion and proeutectic. On the other hand, diffusion is the total net movement of molecules or atoms from a region of higher concentration to a region of lower concentration. Chemical layering in metamorphic rocks is a good example of selforganization in geology. Uphill diffusion, zeroflux planes and transient chemical. Very little phosphorus followed conventional fickian diffusion in the tail region.
We demonstrate a bioinspired artificial photodriven ion pump based on a single polyethylene terephthalate conical nanochannel. Boron uphill diffusion during ultrashallow junction. Uphill diffusion of boron or phosphorus in silicon due to hightemperature proton irradiation is explained by a proposed model in which a vancancy mechanism is assumed. Experimental and simulation study of uphill diffusion of. The uphill diffusion of ru was opposite to and of the same order of magnitude of. Modeling of hydrogen uphill diffusion in dissimilar. Sep 23, 20 the presence of fixed negative surface charges complicates the application of ficks laws in the case of ionic species. Ge implanted samples showed an increase in the b profile peak magnitude with anneal time, as well as its shift towards the surface. Uphill diffusion in multicomponent mixtures chemical. Anomalous enhancement in interfacial perpendicular. Modeling uphill diffusion of mg implants in gaas using. Download the pdf version of osmosis vs diffusion in biology.
In the following ideal conditions will be assumed and concentrations will be used for activities of atoms, ions and various types of defects. Uphill diffusion of carbon in fesic and fesimnc alloys. Uphill effects on hydrogen diffusion coefficients in pd77ag23. Such embrittlement is shown in the cases cited to be due to hydrogen migration and the accumulation of brittle titanium hydrides in the presence of a sharp alloy composition gradient near a weld fusion line. Titanium and its alloys may experience a progressive embrittlement at room temperature leading to catastrophic failure. Uphill diffusion may occur in multicomponent mixtures in which the diffusion flux of any species is strongly coupled to that of its partner species. This is known as uphill diffusion, which is important for a special phase transformation, called spinodal decomposition to be taught in details later in lectures 2224. Local equilibrium between a mineral and an intergranular fluid generates a coupling of diffusion flows which can cause diffusion up the concentration gradient. Unlimited viewing of the articlechapter pdf and any associated supplements and figures. Uphill diffusion, zeroflux planes and transient chemical solitary waves in garnet article pdf available in contributions to mineralogy and petrology 1615. However, few analogs have been produced because extra energy is needed to couple to this uphill process. Diffusion of carbon in austenite with a discontinuity in. Some of the diffusion profiles measured by analytical transmission electron microscope show characteristic features of multicomponent diffusion such as uphill diffusion, chemical solitary waves, zeroflux planes and complex diffusion paths. Pdf uphill diffusion of antioxidant in crosslinked.
The plateau implies that the diffusion flux of n 2 is zero, despite the existence of a large driving force. Modeling uphill diffusion of mg implants in gaas using suprem. This paper presents a new nonlinear diffusion equation which can describe uphill diffusion in a ternary system and provide a criterion in what conditions uphill diffusion will take place. Uphill diffusion in multicomponent mixtures request pdf. Jun 17, 2014 we observed interfacial chemical sharpening due to uphill diffusion in post annealed ultrathin multilayer stack of co and pt, which leads to enhanced interfacial perpendicular magnetic anisotropy. The density at the boundaries is kept fixed to simulate the action of mass reservoirs. Uphill diffusion may occur in multicomponent mixtures in which the diffusion flux of any species is strongly coupled to that of partner species. Anomalous enhancement in interfacial perpendicular magnetic anisotropy through uphill diffusion. Atomic mobilities, uphill diffusion and proeutectic ferrite. Uphill diffusion david keffer department of chemical and biomolecular engineering university of tennessee, knoxville april 22, 2010 our exploration of uphill diffusion, or diffusion of a species counter to its composition gradient, will take the form of an example. The recently observed phenomenon of boron uphill diffusion during lowtemperature annealing of ultrashallow ionimplanted junctions in silicon has been investigated. Uphill diffusion is evident in every oxide and is recognized by local extrema along a diffusion profile. The diffusion is believed to occur via the substitutional. May 20, 2003 the recently observed phenomenon of boron uphill diffusion during lowtemperature annealing of ultrashallow ionimplanted junctions in silicon has been investigated.
Such coupling effects often arise from strong thermodynamic nonidealities. Kinetics of sr and nd exchange in silicate liquids. The uphill diffusion of hydrogen straingradientinduced effects in palladium alloy membranes by f. Starting with the theories of uphill diffusion and reaction diffusion, this paper has developed a physicsbased model explicating why the antioxidant migrates against the concentration gradient. Uphill diffusion of the components is observed fairly often in steels during homogenizing annealing of fecmnsi alloys, e. The pumping process behaving as an inversion of zero. Uphill diffusion of antioxidant in crosslinked polyethylene.
If the activity gradient is of opposite sign, however, then it is possible for diffusion to take place against, or up, the concentration gradient. Assessed thermodynamic and kinetic descriptions have been used. Diffusion of carbon in austenite with a discontinuity in composition author. Difference between osmosis and diffusion in biology compare. In the case of the hydrogen diffusion along the welding line of the titanium alloys, gradients other than hydrogen concentration can lead to a driving force for the movement of hydrogen. Illustration of the processes leading to apparent uphill diffusion in the. The diffusion coefficients for these two types of diffusion are generally different because the diffusion coefficient for chemical diffusion is binary and it includes the effects due to the correlation of the movement. For a multicomponent system, it is prescribed for each pair of species in the system. Uphill diffusion mechanism in protonirradiated silicon. C corrosion 2009 8 uphill hydrogen diffusion an aluminum concentration gradient can cause uphill diffusion in titanium, and the uphill diffusion form of. This is the difference between osmosis and diffusion in biology.
Pdf phase separation and uphill diffusion in the ordered. Download fulltext pdf phase separation and uphill diffusion in the ordered alpha2 compound of a gammatialnb alloy preprint pdf available april 2019 with 35 reads. Pdf uphill diffusion of ultralowenergy boron implants. Instead, interface induced uphill diffusion is found, for the first time, to dominate during low temperature thermal cycles. Boron uphill diffusion during ultrashallow junction formation. A significant feature of the proposed model is that ficks law is included as.
Anomalous enhancement in interfacial perpendicular magnetic. Uphill diffusion and overshooting in the adsorption of binary mixtures in nanoporous solids. Experimental and simulation study of uphill diffusion of al. The presence of fixed negative surface charges complicates the application of ficks laws in the case of ionic species. So, the molecules are moving down a concentration gradient. Cnwra 2009 00 modeling of hydrogen uphill diffusion in.
Figures 2 and 3 also show that kussners results over the lower range of hydrogen contents. Suppression of uphill diffusion caused by phosphorus. Diffusion coefficient is generally prescribed for a given pair of species. Transient, uphill diffusion of implanted mg in gaas during a 900 c anneal is simulated using suprem.
Pdf uphill diffusion, zeroflux planes and transient. Phosphorus redistribution at 500 c was dominated by the uphill diffusion toward the surface region. It is shown that the effect is enhanced by preamorphization, and that an increase in the depth of the preamorphized layer reduces uphill diffusion in the highconcentration portion of boron profile, while increasing transient. In the majority of cases, the diffusion process can be adequately described by ficks law that postulates a linear relationship between the flux of any species and. The uphill diffusion of n 2 continues to take place until the time t t 1 is reached, when the composition profiles in both bulbs tend to plateau. Diffusion in silicate melts often shows uphill diffusion, the diffusion of a component up its own concentration gradient. An experimental study of diffusion of al, ni, and pt in a ptcoated binary nial alloy has been made and compared with a computer simulation. The results calculated from the model show good agreement with the experimentally measured profiles, and some physical parameters can be estimated. Prob lems of the occurrence of simultaneous induce ment of gorsky effects in the course of measurements of hydrogen diffusion coeff. We observed interfacial chemical sharpening due to uphill diffusion in post annealed ultrathin multilayer stack of co and pt, which leads to enhanced interfacial perpendicular magnetic. Transient enhanced diffusion ted is minimal at these low energies, since excess interstitials are very close to the surface. Diffusion path and isoactivity line for the diffusion couple to illustrate uphill diffusion of c in fcc femnc alloys graphite is chosen as the reference state. Uphill diffusion and overshooting in the adsorption of. Starting from the measured experimental concentration profiles after 1 h heat treatment at 1173 k the simulation is compared to the experimentally determined profiles after 11.
But everything in here is said in more detail, and better, in weickerts paper. In this example, we will consider a three component. Cao exhibits the most extreme manifestation of uphill diffusion, and. Nonlinear diffusion these notes summarize the way i present this material, for my bene. Save the file in the language directory of airomate. Molecular diffusion is an omnipresent phenomena that is important in a wide variety of contexts in chemical, physical, and biological processes. Pdf boron uphill diffusion during ultrashallow junction.
This diffusion is always a nonequilibrium process, increases the system entropy, and brings the system closer to equilibrium. The sid mechanism is shown to be equivalent, in terms of the. This implies that the diffusion in the shoulder region was not governed by the concentration gradient of phosphorus. Uphill diffusion of ultralowenergy boron implants in preamorphized silicon and silicononinsulator. Uphill diffusion and a new nonlinear diffusion equation in.
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