Anisotropic mechanical properties of zircon and the effect of radiation damage

作者：Beirau Tobias^*; Nix William D; Bismayer Ulrich; Boatner Lynn A; Isaacson Scott G; Ewing Rodney C

来源：Physics and Chemistry of Minerals, 2016, 43(9): 627-638.

DOI：10.1007/s00269-016-0822-9

• Zircon
• Radiation damage
• alpha-Decay
• Metamictization
• Nanoindentation
• Mechanical properties

This study provides new insights into the relationship between radiation-dose-dependent structural damage due to natural U and Th impurities and the anisotropic mechanical properties (Poisson's ratio, elastic modulus and hardness) of zircon. Natural zircon samples from Sri Lanka (see Muarakami et al. in Am Mineral 76:1510-1532, 1991) and synthetic samples, covering a dose range of zero up to 6.8 x 10(18) alpha-decays/g, have been studied by nanoindentation. Measurements along the [100] crystallographic direction and calculations, based on elastic stiffness constants determined by A-zkan (J Appl Phys 47:4772-4779, 1976), revealed a general radiation-induced decrease in stiffness (similar to 54 %) and hardness (similar to 48 %) and an increase in the Poisson's ratio (similar to 54 %) with increasing dose. Additional indentations on selected samples along the [001] allowed one to follow the amorphization process to the point that the mechanical properties are isotropic. This work shows that the radiation-dose-dependent changes of the mechanical properties of zircon can be directly correlated with the amorphous fraction as determined by previous investigations with local and global probes (Rios et al. in J Phys Condens Matter 12:2401-2412, 2000a; Farnan and Salje in J Appl Phys 89:2084-2090, 2001; Zhang and Salje in J Phys Condens Matter 13:3057-3071, 2001). The excellent agreement, revealed by the different methods, indicates a large influence of structural and even local phenomena on the macroscopic mechanical properties. Therefore, this study indicates the importance of acquiring better knowledge about the mechanical long-term stability of radiation-damaged materials.

• 出版日期2016-10