An Investigation of the Exchange between a Metal and Ions in Solution by Using Radioactive Indicators

Rollin, B V

doi:10.1021/ja01858a021

Cited by 11 publications

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“…The fact that the penetration of radioactive silver atoms into single-crystal specimens at room temperature follows a relation similar to that for grain-boundary diffusion rather than to that for volume diffusion at high temperatures suggests that silver diffuses at room temperature along dislocation "pipes," which behave like tiny grain boundaries. The equation derived by Fisher (1,6) for grain-boundary diffusion may then be used to calculate the diffusion coefficient. This equation is…”

Section: Calculation Of Diffusion Coefficientmentioning

confidence: 99%

“…The exchange of silver ions between polycrystalline silver metal surfaces and aqueous solutions of silver salts has been investigated by a number of workers using radioactive silver isotopes as tracers (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11). In general, all agree that a rapid exchange involving only a few atom layers takes place in the first few seconds, followed by a slower process which is affected by the concentration of the solution, the state of the surface, and the temperature.…”

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Exchange of Silver Ions at Single Crystal/Solution Interfaces

Tingley

1965

J. Electrochem. Soc.

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The exchange of silver ions between the (111), (100), (110), and (311) surfaces of single-crystal silver and silver nitrate solutions has been studied, using Ag 110 as tracer. The initial step is very rapid and is probably largely adsorption, since much of the radioactivity acquired during the first few seconds can be removed by soaking in distilled water. After about 15 rain the ratecontrolling process appears to be diffusion in the solid. In 0.01M AgNO~ solution the radioactivity uptake continues steadily if the surfaces are frequently desorbed with distilled water, but if the adsorbed ions are allowed to remain, the rate of uptake is reduced. In 0.1M AgNO8 solution the radioactivity on the surfaces reaches constant values after 4 days, whether or not desorption is carried out. The penetration profile and diffusion coefficient in the metal were obtained by "chemical sectioning." It was found that diffusion occurred by means of "dislocation pipes," and resembled grain boundary diffusion rather than lattice diffusion by a vacancy mechanism which occurs at high temperatures.The exchange of silver ions between polycrystalline silver metal surfaces and aqueous solutions of silver salts has been investigated by a number of workers using radioactive silver isotopes as tracers (1-11). In general, all agree that a rapid exchange involving only a few atom layers takes place in the first few seconds, followed by a slower process which is affected by the concentration of the solution, the state of the surface, and the temperature. This slower uptake of ions from the solution is held to be controlled by diffusion in the solid. King and Levy (2) found that surfaces that were removed from the solution, and washed frequently, underwent more exchange than surfaces that were left undisturbed; they attributed this to the removal of adsorbed salt that slowed down the exchange. However, King and McKinney (3) concluded that the increased exchange was due, more likely, to increased diffusion caused by a rise in temperature due to the hot water used in the washing. They calculated a grain boundary diffusion coefficient of the order of 10 -21 cm2/sec. Sandor (8), who removed the radioactivity by electroetching, obtained a value of 1.37 x 10 -20 cm2/sec for the grain boundary diffusion coefficient.The present work was undertaken to ascertain the behavior of specific single-crystal surfaces with respect to the exchange of silver ions with aqueous silver nitrate solutions, and to obtain a value for the room temperature volume diffusion coefficient. Experimental DetailsThe single crystals of silver were grown in a horizontal furnace by the method of Chalmers (12), using 99.999% pure silver obtained from Johnson, Matthey and Mallory Limited, Toronto. The crystals were then sectioned and oriented along the desired direction, and the resulting surfaces were electroetched and/or chemically etched and polished, as described below. Most cuts were made using a spark cutter, but two specimens were cut by means of an "acid saw." The orientation of ...

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Section: Calculation Of Diffusion Coefficientmentioning

confidence: 99%

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confidence: 99%

Exchange of Silver Ions at Single Crystal/Solution Interfaces

Tingley

1965

J. Electrochem. Soc.

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“…The heterogeneous exchange reaction between zinc and .its ions has been studied by Rollin (2) in zinc dust, by Gaudin and Vincent (3), Haenney and Mivelaz (4), Matsura (5), and King and Evans (6), in both zinc dust and zinc foil; and Bushmanov and Vozdvizhenlry (7) in zinc single crystals. There are collsiderable variations in the results obtained by the different authors in this field, due to the fact that some factors, such a s surface preparation, oxidation, corrosion, are not always fully considered.…”

Section: Introductionmentioning

confidence: 99%

Exchange Reactions Between Zinc and Its Ions

Sandor¹

1961

Can. J. Chem.

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The exchange reaction between zinc metal and zinc ions in solution has been studied by means of radioactive zinc-65. Polycrystalline zinc and bicrystals of zinc were used under conditions where the radioactive material was incorporated either in the solid or the liquid phase. Strain-free clean surfaces were obtained and autoradiographs taken.The results of the experiments using bicrystals were interpreted on the basis that a local cell action sets up an electrochemical potential between liquid and solid a t the beginning of the reaction. Exchange was found to take place in both directions, but the reaction did not follow a simple logarithmic law. INTRODUCTIONThe extensive use of radioisotopes has made possible the study of many exchange reactions. In 1915, Hevesy ( I ) showed that in the system Pb++/Pb(N03)2 a deep exchange talres place in a very short period of time, i.e. more than one monolayer exchanges, and this was found later to happen in other metals, too. Various mechanisms have been suggested for such exchange reactions, but no conclusive explanation has yet been p u t forward. In the general case one expects more or less rapid exchange in the surface layer, followed by slow penetration to the interior of the metal a t a speed controlled by the diffusion coefficient and orientation of the crystals.The heterogeneous exchange reaction between zinc and .its ions has been studied by Rollin (2) in zinc dust, by Gaudin and Vincent (3), Haenney and Mivelaz (4), Matsura (5), and King and Evans (6), in both zinc dust and zinc foil; and Bushmanov and Vozdvizhenlry (7) in zinc single crystals. There are collsiderable variations in the results obtained by the different authors in this field, due to the fact that some factors, such a s surface preparation, oxidation, corrosion, are not always fully considered.In this investigation, zinc metal was dipped in different solutions of zinc salt to show that the exchange reaction ZnO,,,,, @ Zn++,,l takes place in both directions. This was done by labeling either the metal or the zinc solution with radioactive zinc-65, and following the change in activity for different times of immersion. The influence of oxide or hydroxide on the exchange was also investigated. Finally, the exchange reaction between zinc bicrystals and carrier-free solutions of ZnG was studied.The following factors were considered of importance in this study: (1) preparing undistorted zinc surfaces; (2) working in an oxygen-free atmosphere; (3) minimizing of corrosion and adsorption. I t is known that zinc is a soft metal, easily worlred, and t h a t the depth of distorted metal after mechanical polishing may commollly extend to a t 'Manuscript received M a y I S , 1960.

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“…In 1940 Rollin (2) extended the work of Hevesy by using radioactive silver in solution and measuring the exchange on silver, gold, and platinum immersed in the solution. All three metals acquired an activity representing the transference of ~bout 100 atom layers of silver from the solution.…”

Section: Introductionmentioning

confidence: 99%

“…They suggest that two exchange mechanisms are involved: (a) the electrochemical, accounting for most of the activity taken up by the crystalline areas, and (b) the kinetic, responsible for the activity taken up by the polished surfaces and the anodic areas of cold-worked specimens/ None of these studies show evidence of the surface distribution of the active ions, nor do they draw conclusions from their results regarding the over-all magnitude of the local cell currents. In the present work, the mechanism of exchange has been studied with radioactive cobalt ions in solutions into which 2 The work of Haissinsky (7) and his collaborators with radioactive solutions and their study of eleetrodeposition from dilute solutions deserves special attention. Orabsent present 4.9 X 10 -9 3.1 X 10 -9 1.7 X 10 -9 8.1 X 10 -9 1.5 X 10 -7 5.7 X 10 -9 6.5 X 10 -9 1.3 X 10 -9 0 1.1 • 10 -0 3.9 X 10 -s 1.4 X 10 -s 0 2.3 X 10 -~ 3.1 X 10 -s 1.3 X 10 -1~ Atom layers/cm 2 O~-absent 1.5 X 10 -s 1.2 X 10 -9 3.1 X 10 -s 3.2 X 10 -9 2.9 X 10 -7 0 4.1 X 10 10 5.1 X 10 -s 1.6 X 10 -s 0.9 X 10 -1~ have also been made of the magnitudes of the local cell currents on the metal surfaces.…”

Section: Introductionmentioning

confidence: 99%

The Mechanism of Exchange Between Radioactive Ions in Solution and Metal Surfaces

Slmnad¹,

Ruder²

1951

J. Electrochem. Soc.

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The mechanism of exchange between metals and ions in solution has been studied with radioactive cobalt ions in solutions into which various metals with different surface treatments were immersed in the presence and absence of oxygen. The metals were washed after various times of immersion in the solutions, their acquired radioactivities measured, and the distribution of radioactive cobalt on the surfaces shown by means of autoradiographs. The results indicate that local cell action, due to differences of potential on the metal surfaces, is the factor which governs the radioactivity acquired by the metals. By applying Faraday's law, it has been possible to calculate the magnitudes of local cell currents on the metal surfaces from the acquired activities.

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An Investigation of the Exchange between a Metal and Ions in Solution by Using Radioactive Indicators

Cited by 11 publications

References 0 publications

Exchange of Silver Ions at Single Crystal/Solution Interfaces

Exchange of Silver Ions at Single Crystal/Solution Interfaces

Exchange Reactions Between Zinc and Its Ions

The Mechanism of Exchange Between Radioactive Ions in Solution and Metal Surfaces

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