Swift heavy ion-induced amorphization of CaZrO3 perovskite

Abstract

Perovskite, ABO3, structures are an important class of ceramics with a large variety of derivative structure-types (cubic, tetragonal, hexagonal, orthorhombic, and rhombohedral). Radiation damage in perovskites is of interest due to their potential as actinide waste forms and to understand radiation effects in uranium- and thorium-bearing phases. Powder CaZrO3 perovskite was irradiated with 940-MeV Au ions up to 1.5×1013ions/cm2. Changes in the crystal structure were followed in situ as function of fluence by means of a sequence of X-ray diffraction (XRD) measurements. Ion-induced amorphization is evidenced by a decrease in diffraction intensity and an increase in diffuse scattering. Based on XRD measurements, as well as transmission electron microscopy (TEM), CaZrO3 is completely amorphized at a fluence of 1.5×1013ions/cm2. From the evolution of the integrated XRD-maxima intensities with fluence, the diameter of the amorphous tracks is estimated to be 6.0±0.6nm, which is independently confirmed by bright-field TEM images: 6.7±0.4nm. Changes in the positions of diffraction maxima may be caused by at least two processes. Broadening of the diffraction maxima is analyzed using a Williamson–Hall plot. Strain-induced broadening is the dominant process.