Irradiation induced order–disorder phase transformation in A4Zr3O12 (A = Sc, Lu and Dy)

In this study, 200 keV Ne+ ion irradiations were performed under cryogenic conditions (∼77 K) on δ-phase oxide compounds with formula, A4Zr3O12 (A = Sc, Lu and Dy). An order-to-disorder (O–D) phase transformation was observed in δ-Lu4Zr3O12 and δ-Sc4Zr3O12 after Ne+ ion irradiation, but no phase change was observed in Dy4Zr3O12. The latter compound exhibited a disordered fluorite structure before and after irradiation. The threshold doses to produce O–D phase transformations using Ne+ ions were found to be significantly lower than for similar irradiations (reported previously) using Kr++ ions. This suggests that light ions are more efficient than heavy ions in producing the retained defects that are ultimately responsible for the observed O–D transformation. The ion irradiation-induced O–D transformations observed here are discussed in terms of analogous transformations found in temperature–composition (T–C) phase diagrams for A4Zr3O12 compounds.