Strong irradiation tolerance to amorphization in delta-Sc4Ti3O12

Abstract

Polycrystalline delta-phase Sc4Ti3O12 was irradiated under two separate conditions, with 200keV Ne+ or 600keV Kr3+ at cryogenic temperature (∼77K) to examine its radiation tolerance to amorphization. Irradiated samples were characterized using grazing incidence X-ray diffraction and cross-sectional transmission electron microscopy. An order-to-disorder (O–D) structural transformation was observed under both ion beam irradiation conditions, but the threshold irradiation doses to produce the O–D transformation differ significantly. The order to disorder phase transformation was completed by a fluence of 2×1019Ne/m2 (or a peak dose of ∼0.7dpa) with Ne irradiation, while it was not accomplished until a fluence of 5×1020Kr/m2 (or a peak dose of ∼93dpa) with Kr irradiation. This observation was interpreted in terms of greater probability of defect survivability in dilute Ne versus dense Kr ion cascades. More interesting aspect in this study, in the basis of so-called “chemical effects”, Ti-bearing oxide Sc4Ti3O12 should be readily amorphous when exposed to ion irradiation, but no amorphization was observed even after 93 displacements per atom in Kr irradiation. These observations exhibit that the temperature–composition (T–C) phase diagram is a good indicator for radiation tolerance, especially for amorphization.