Radiation-Induced Effects on Material Properties of Ceramics: Mechanical and Dimensional Properties

Raman scattering is applied to probe the radiation damage in swift heavy ionirradiated ceramics, namely zirconium nitride (ZrN), ceria (CeO 2 ), and yttriastabilized zirconia (ZrO 2 : Y, or YSZ) for about the same high electronic stopping power of heavy ions. Raman spectra show that these ceramics are radiationresistant materials that are not amorphized by such irradiations even for large ion track overlap at high fluences. However, for ZrN, the increase of the TA/LA and TO/LO band intensities versus fluence is evidenced after 100-MeV Xe ion irradiation up to a saturation for the fluence of 3 Â 10 12 cm À2 . The band growths are ascribed to the increase of the concentration of Zr and N vacancies induced by electronic excitations inside tracks. However, the diffuse reflectance spectra do not exhibit any clear modifications of the electronic structure. For ceria, the decrease and broadening of the main F 2g peak of the fluorite-like structure and the growth of a broad defect band assigned to oxygen vacancy formation is observed versus fluence up to 10 14 cm À2 for 200-MeV Xe ion irradiation. For YSZ, Raman spectra mainly give evidence of the intrinsic lattice disorder due to the native oxygen vacancies even up to high fluences of about 3 Â 10 13 cm À2 for 200-MeV I and 200-MeV Au ion irradiation. Results are discussed on the basis of the interplay between the native structural disorder and the radiation-induced disorder by electronic excitations in these three materials.

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