Diffusion of Krypton in Cesium and Rubidium Iodide; A Comparison of Results Obtained Following Reactor Irradiation and Ion Bombardment

Abstract The present study shows that under suitably chosen conditions, the same results of rare gas diffusion coefficients can be obtained in samples which are reactor irradiated to produce a homo-geneous concentration of rare gas, and in samples that are labeled with rare gas by controlled ion bombardment. In the present study, the diffusion of krypton in Rbl and Csl was found to follow the empirical rule of yielding activation enthalpies in the range (1.4±0.2) x 10-3 Tm eV, with Tm = melting point in °K. Trapping of rare gases (gas-gas or gas-damage interactions) was observed at high gas concentration.

Download Full-text

Fission gas diffusion in uranium dioxide

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1978.0213 ◽

1978 ◽

Vol 364 (1719) ◽

pp. 473-497 ◽

Cited By ~ 52

Keyword(s):

Experimental Study ◽

Chemical Composition ◽

Diffusion Coefficients ◽

Gas Diffusion ◽

Rare Gas ◽

Ionic Crystals ◽

Gas Migration ◽

Fission Gas ◽

And Migration ◽

And Diffusion

We present the results of a theoretical investigation of the trapping and migration of the fission gas atoms, Kr and Xe in UO 2 . Our models differ from those previously presented in discussions of rare gas diffusion in ionic crystals. We propose that trapping occurs at vacancy aggregates, and that detrapping into interstitial sites is unimportant; gas migration is effected by the intrinsic mobility of the gas-trap complexes. We suggest that the trapping and diffusion of the two gas atoms occur by different mechanisms, owing to their different sizes. Our results explain many of the observations of the experimental study of Felix & Miekeley and emphasize the importance of the chemical composition of the fuel on gas diffusion coefficients. The contradictions between this work and the earlier studies summarized by Matzke is, we suggest, possibly due to the higher levels of radiation damage which may have been present in the crystals used in the latter work.

Download Full-text

Rare gages implanted in lunar fines

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1977.0079 ◽

1977 ◽

Vol 285 (1327) ◽

pp. 391-395 ◽

Cited By ~ 5

Keyword(s):

Radiation Damage ◽

Lunar Regolith ◽

Lunar Soil ◽

Rare Gas ◽

Concentration Profiles ◽

Rare Gases ◽

Gas Concentration ◽

Governing Factor ◽

Solar Abundances ◽

A New Technique

Rare gases implanted into lunar fines can be used to study processes in the lunar regolith as well as solar abundances. A short outline of some basic results about the distribution of solar rare gases in lunar soils is given and illustrated by two case studies: (1) Evidence for local endogenic activity near Shorty Crater is inferred from rare gas fractionations in soil 74241. (2) Rare gas concentration profiles measured with a new technique in single lunar soil particles underline the importance of radiation damage as governing factor of migration and promise future possibilities to determine ancient solar abundances free of secondary bias.

Download Full-text

Rare Gas Diffusion in NaCl

Zeitschrift für Naturforschung A ◽

10.1515/zna-1969-0518 ◽

1969 ◽

Vol 24 (5) ◽

pp. 820-826 ◽

Cited By ~ 2

Author(s):

Hj. Matzke ◽

G. Rickers ◽

G. Sørensen

Keyword(s):

Single Crystals ◽

Volume Diffusion ◽

Bulk Material ◽

Gas Diffusion ◽

Rare Gas ◽

Release Mechanism ◽

Rare Gases ◽

Obvious Effect ◽

Vacancy Clusters ◽

Very High

Abstract The mobility (diffusion and trapping) of the heavy rare gases Kr, Xe, and Rn in pure and doped NaCl single crystals was measured following ion bombardment to various integrated doses (108 to 2X1016 ions/cm2) and at energies between 30 and 500 keV. No obvious effect of doping on release was found. At low gas concentrations, release was compatible with volume diffusion yielding an activation enthalpy, ΔH, of 1.5 ±0.2 eV. This value was obtained for both very low and very high bombardment energies (≈ 1 and 500 keV) thus indicating that the same release mechanism is operative near the surface and in the bulk material. For this release mechanism, a mobility in small vacancy clusters was suggested. At higher gas concentrations, the release was shifted towards higher temperatures. This retarded release was explained by transient trapping, i. e. by gas-gas or gas-damage interactions, and was shown to have a partially single jump character. Again, the result was the same for low and high bombardment energies.

Download Full-text

Inert gas diffusion and radiation damage in ionic crystals and sinters following ion bombardment

Canadian Journal of Physics ◽

10.1139/p68-077 ◽

1968 ◽

Vol 46 (6) ◽

pp. 621-634 ◽

Cited By ~ 58

Author(s):

Hj. Matzke

Keyword(s):

Radiation Damage ◽

Diffusion Mechanism ◽

Ion Bombardment ◽

Gas Diffusion ◽

Absolute Temperature ◽

Diffraction Measurement ◽

Ionic Crystals ◽

Rare Gases ◽

Self Diffusion ◽

Diffusion Phenomena

A review is given of radiation damage and diffusion phenomena in a large variety of ionic crystals (oxides and halides) and two metals following ion bombardment. Ion beams of both light and heavy nuclides between mass number 3 (tritium) and 222 (emanation) were employed. The ion doses varied between 104 and 1017 ions/cm2. Four different experimental techniques were used to detect gross structural radiation damage following bombardment: reflection electron diffraction, measurement of ranges or penetration profiles, electron microscopy in transmission or using replica techniques, and gas release measurements at low temperatures. In general, materials having cubic lattice structures were shown to be more stable than anisotropic substances.Minor local damage (such as point defects, defect clusters or voids, dislocations and loops) was studied by its interaction with rare gases or other volatile elements (Br, Rb, Cs). For the heavy rare gases (Kr, Xe, Em) and low bombardment doses, volume diffusion was observed starting between 0.4 and 0.5 of the melting point, Tm, on the absolute temperature scale. The activation enthalpies ΔH were about 80 ± 10% of those for the self-diffusion of the less mobile lattice ions and were related to Tm via ΔH = (1.4 ± 0.2) × 10−3Tm eV = (32 ± 4) Tm kcal/mole. For the diffusion mechanism, a relation with self-diffusion is suggested, the gas most probably migrating in small vacancy clusters.

Download Full-text

The observation of nano-voids in Au thin films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126627 ◽

1987 ◽

Vol 45 ◽

pp. 366-367

Author(s):

William Krakow

Keyword(s):

Thin Films ◽

Melting Point ◽

Present Author ◽

Stacking Faults ◽

Damage Threshold ◽

Ionic Species ◽

Rare Gases ◽

Chain Defects ◽

Vacancy Chains ◽

Au Thin Films

It has long been known that defects such as stacking faults and voids can be quenched from various alloyed metals heated to near their melting point. Today it is common practice to irradiate samples with various ionic species of rare gases which also form voids containing solidified phases of the same atomic species, e.g. ref. 3. Equivalently, electron irradiation has been used to produce damage events, e.g. ref. 4. Generally all of the above mentioned studies have relied on diffraction contrast to observe the defects produced down to a dimension of perhaps 10 to 20Å. Also all these studies have used ions or electrons which exceeded the damage threshold for knockon events. In the case of higher resolution studies the present author has identified vacancy and interstitial type chain defects in ion irradiated Si and was able to identify both di-interstitial and di-vacancy chains running through the foil.

Download Full-text