Vacancies, divacancies, and self‐diffusion in platinum

Schumacher, Dieter; Seeger, A.; Härlin, O/

doi:10.1002/pssb.19680250135

Cited by 66 publications

(16 citation statements)

References 31 publications

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“…Thus, we want to report the results of a systematic study of the dependence of the recovery after electron irradiation of platinum on electron energy, dose, and doping. The choice of platinum for this study has been motivated, mainly, by the fact that rather reliable and detailed vacancy data exist for this metal (5,6) from quenching and equilibrium measurements. This should help to clarify the role of vacancy migration in the temperature range of stage 111.…”

Section: Introductionmentioning

confidence: 99%

Recovery of electron-irradiated platinum

et al. 1972

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Using electrical resistivity mcasurements the recovery in stage I of electron irradiated Pt has been studied. The influences which exert a large variation of irradiation dose, electron energy, radiation doping and doping with dilute concentrations of Au-atoms on the annealing structure were investigated. The recovery in substages IA, IB and IC is not influenced by irradiation dose and doping agents in agreement with the model of close Frenkel-pair recombination in these stages. Substage IE is strongly and substage ID is moderately modified by variation of radiation dose and the addition of doping agents. This and the equal values of the activation energies measured in substage ID and IE confirm the model of correlated and uncorrelated recovery of free migrating interstitials in these stages.

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Section: Introductionmentioning

confidence: 99%

Recovery of electron-irradiated platinum

et al. 1972

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“…Ebenso erhielten Schumacher et al [9] zwei Energien E = 1,33 eV und E = 1,0 eV. Sie dcuten E = 1,0 eV als Differenz zwischen der Wanderungsenergie voii Doppelleerstellen und der Bindungsenergie fur Doppelleerstellen ( E g -B,).…”

Section: Einicitungunclassified

“…Entweder ist im Platin die Leerstellenkonzentration ungewohnlich hoch (cv(T,) = [lo, 111) oder der spezifische Widerstand der Leerstellen liegt betrachtlich hoher als in anderen k.f.z.-Metallen. Schumacher et al [9] kommen in ihrer Diskussion zu der SchluBSolgerung, daB e, hochstens 6 x Q cm betragen sollte. Aus den von ihnen gemessenen Apo und berechnetem c, bei T , = 1000 "C ergibt sich jedoch e, = 11,6 x !2 cm.…”

Section: Diskussionunclassified

“…Wahrend Schumacher et al [9] in Ubereinstimmung mit der Vorstellung, daB bei relativ kleinen Abschrecktemperaturen die Doppelleerstellen vernachlassigt Abschrekken von Aluminium gefunden wurden. Fur letzteres spricht eine kleine Ausheilstufe zwischen 800 und 950 "C, die wir nach Abschrecken von hoheren Temperaturen, nicht aber an nur verformtem Material fanden und die mit dem Auflosen dieser Komplexe gedeutet werden konnte.…”

Section: Diskussionunclassified

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Leerstellenausheilung in Platin nach Abschrecken unter Argonatmosphäre und in Wasser

Rattke¹,

Hauser²,

Wieting³

1969

Physica Status Solidi (b)

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a), 0. HAWSER (b) und J. WIETING (a) Es wird iiber Untersuchungen zum Ausheilverhalten abgeschreckter Platinproben in Abhtingigkeit von der Abschrecktemperatur, der Abschreckgeschwindigkeit und vom pbysikalischen Zustand der Proben berichtet. Dabei zeigt es sich, daB niedrige Wanderungsenergien fur Leerstellen von 1,0 bis 1,1 eV unabhangig von der eingefrorenen Leerstellenkonzentration immer dann erhalten werden, wenn bereits vor dem Abschrecken eine hohe Versetzungsdichte vorliegt oder wenn bei hohen Abschreckgeschwindigkeiten durch Verformungen wahrend des Abschreckens die Senkendichte verandert wird. Hohere Wanderungsenergien von 1,3 bis 1,4 eV treten bei gut vorgegluhtem Material und hinreichend langsamen Abschreckgeschwindigkeiten ebenfalls unabhangig von der Leerstellenkonzentration auf. Sie sollten der freien Wanderung von Einzelleerstellen zugeschrieben werden, wahrend die kleineren Energien zusatzliche Wechselwirkungen mit den Senken enthalten. Unter diesen Umstanden stellt die chemische Reaktionsgleichung keine gute Ntiherung fur die Beschreibung des Ausheilvorganges dar. Ein EinfluB von Doppelleerstellen auf die Ausheilung kann erst erfaBt werden, wenn bei hinreichend senkenarmem Material eine Verformung wahrend des Abschreckens ausgeschlossen werden kann.The report deals with the recovery of platinum wires in dependence on the temperature, quenching rate, and the physical state of the platinum samples. Herewith it is shown that low vacancy migration energies (1.0 to 1.1 eV) always can be obtained independent of the concentration of the quenched-in vacancies if already before the quenching a high density of dislocations exists or if a t high quenching rates a change in the density of sinks occurs due to deformation. Higher migration energics (1.3 to 1.4 eV) are observedalso independent of the concentration of vacanciesif the samples are well annealed and the quenching rate is sufficiently slow. It seems reasonable to assign them to the free migration of monovacancies. The smaller energies contain an additional interaction with the sinks. Under these conditions the chemical rate equation gives no good approximation for the description of the recovery. An influence of divacancies will only be obtained if the samples have a sufficiently small density of sinks and a deformation during quenching may be excluded.

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“…equivalent to one vacancy in 8 × 10 14 10 nm-diameter Pt nanoparticles) [8]. Similarly, the bulk migration energy (∼1.5 eV) yields bulk diffusion coefficients of order 10 −27 cm 2 = sec [9]; this is geologically slow in comparison to the minutes time scale of the rt-KE. To account for higher vacancy concentrations in Pt-shell particles in acid electrolytes, it is hypothesized that experimental procedures lead to an excess of vacancies at the core-shell interface; similarly, fast vacancy diffusion can be induced in simulation, but only by imposing unrealistically high driving forces [10].…”

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confidence: 99%

Mechanism of Hollow Nanoparticle Formation Due to Shape Fluctuations

Erlebacher

Margetis

2014

Phys. Rev. Lett.

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Shape fluctuations in nanoparticles strongly influence their stability. Here, we introduce a quantitative model of such shape fluctuations and apply this model to the important case of Pt-shell/transition metal-core nanoparticles. By using a Gibbs distribution for the initial shapes, we find that there is typically enough thermal energy at room temperature to excite random shape fluctuations in core-shell nanoparticles, whose amplitudes are sufficiently high that the cores of such particles are transiently exposed to the surrounding environment. If this environment is acidic and dissolves away the core, then a hollow shell containing a pinhole is formed; however, this pinhole quickly closes, leaving a hollow nanoparticle. These results favorably compare to experiment, much more so than competing models based on the room-temperature Kirkendall effect.

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Vacancies, divacancies, and self‐diffusion in platinum

Cited by 66 publications

References 31 publications

Recovery of electron-irradiated platinum

Recovery of electron-irradiated platinum

Leerstellenausheilung in Platin nach Abschrecken unter Argonatmosphäre und in Wasser

Mechanism of Hollow Nanoparticle Formation Due to Shape Fluctuations

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