Channeling Study of the Damage Induced in Ion-Irradiated Ceramic Oxides
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Channeling Study of the Damage Induced in Ion-Irradiated Ceramic Oxides Lionel Thomé, Aurélie Gentils, Frédérico Garrido, Jacek Jagielski1 Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, F-91405 Orsay, France 1 Institute of Electronic Materials Technology, PL-01-919 Warsaw, Poland ABSTRACT The evaluation of the damage generated in crystalline ceramic oxides placed in a radiative environment is a major challenge in many technological domains. The use of the channeling technique is particularly well adapted to measure the depth distribution of the irradiation-induced disorder and to monitor the damage build-up. This paper describes the methodology used for the study of radiation damage with the channeling technique, presents a new method of analysis of channeling data based on Monte-Carlo simulations and provides recent results concerning the damage induced in ion-bombarded ceramic oxide single crystals in both nuclear (low-energy ion irradiation) and electronic (high-energy ion irradiation) slowing-down regimes.
INTRODUCTORY REMARKS Oxides are key engineering materials, widely used in electronic, space and nuclear industry. For many applications related to these technological domains, information on the radiation resistance of oxides is firmly required. A topical example is provided by ceramics used as potential matrices for the immobilization and/or transmutation of radioactive waste [1-4]. These materials should survive long-time exposure in a severe radiative environment, mostly due to the α-decay of actinide elements (i.e. 5 - 6 MeV α-particles and ~ 100 keV heavy recoil nuclei) and the impact of fission fragments (i.e. 70 - 100 MeV heavy ions). The interactions between an energetic ion and a solid target may be split into two broad categories [5]: (a) the tranfer of energy to atomic nuclei by ballistic processes (hereafter referred to as nuclear energy loss, Sn) which is dominant at low ion velocities (i.e. below ~ 10 keV/u); (b) the transfer of energy to electrons by excitation and ionization processes (hereafter referred to as electronic energy loss, Se) which contributes the most to the slowing-down of swift ions (i.e. above ~ 1 MeV/u). For instance the interactions of fission fragments essentially involve electronic energy loss, whereas α-decay concerns both processes (electronic excitation for αparticles and ballistic collisions for recoil nuclei). A rather broad panoply of experimental techniques may be implemented to study the damage formation in solids submitted to ion irradiation. Among them, Rutherford backscattering and channeling (RBS/C) of light particles [6] is particularly well adapted to such a purpose, both to determine the disorder depth distribution (damage profiling) and to monitor the variation of the disorder as a function of the ion fluence (disorder build-up), provided that single crystals are used for the study. Moreover, since oxides are generally binary or ternary compounds with cationic and anionic sublattices, the combination of standard RBS and nuclear react
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