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Relation entre le gonflement et la creation de defauts dans les cristaux ioniques irradies par des ions lourds rapides

Abstract : When fast heavy ions penetrate in matter, they slow down essentially by depositing their energy on the electrons. This can lead to strong electronic excitation densities in the solid and then to structural modifications. In this work, calcium fluoride (CaF2) was used to look further into the damage induced by irradiation with fast heavy ions in ionic crystals. Four techniques were mainly employed to characterise this damage. These techniques of analysis are wide angle X-ray diffraction, surface profilometry, Rutherford backscattering spectrometry and UV-visible optical absorption spectroscopy. The results of this work show that CaF2 answers in a multiple way to the electronic excitations. For stopping powers higher than approximately 5 keV/nm, a polygonization seems to occur. This causes a structural disorder, a swelling of 0.27 % and the formation of fractures in the material. A second damage mechanism is caused above approximately 13 keV/nm and results in a loss of the initial crystalline structure. However, optical centres appear whatever the ion stopping power, which indicates that these defects cannot be the cause of the two above mentioned damage mechanisms. According to a thermal spike model, the two thresholds can be linked to melting and sublimation energy of the material, respectively.
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Contributor : Marc Boccanfuso <>
Submitted on : Wednesday, December 11, 2002 - 7:37:52 PM
Last modification on : Friday, March 5, 2021 - 3:00:35 PM
Long-term archiving on: : Friday, April 2, 2010 - 6:15:23 PM

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  • HAL Id : tel-00002023, version 1

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Marc Boccanfuso. Relation entre le gonflement et la creation de defauts dans les cristaux ioniques irradies par des ions lourds rapides. Physique [physics]. Université de Caen, 2001. Français. ⟨tel-00002023⟩

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