Article ID Journal Published Year Pages File Type
1446083 Acta Materialia 2013 14 Pages PDF
Abstract

The phase transformations induced by electronic excitation (Se) and ballistic processes (Sn) in Nd2Zr2O7 pyrochlores irradiated with heavy ions in three domains of energy (∼1 GeV, ∼100 MeV and a few MeV) were investigated by X-ray diffraction, Raman spectroscopy and transmission electron microscopy. In the Se regime at high energy, results show that: (i) ion tracks are formed above a Se threshold of 12.5 keV nm−1; (ii) both pyrochlore → anion-deficient fluorite phase transition and amorphization occur; (iii) total amorphization is always observed at the highest fluences; (iv) the internal structure (amount of amorphous phase vs. its anion-deficient fluorite counterpart) and the diameter of tracks depend on many parameters such as Se, the deposited energy density and the recrystallization rate. For irradiations performed with low-energy ions in the Sn regime, only the anion-deficient fluorite phase is formed up to a dose of 40 dpa. Thus Nd2Zr2O7 exhibits an unusual behaviour since this compound is amorphizable by Se and non-amorphizable by Sn. Annealing of totally amorphized Nd2Zr2O7 samples reveals strong differences in the recovery processes with other pyrochlore materials that are related to their different chemical compositions.

Related Topics
Physical Sciences and Engineering Materials Science Ceramics and Composites
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