10 MeV Au ion irradiation effects in an MgO–HfO 2 ceramic–ceramic (CERCER) composite

Abstract

Room temperature ion irradiation damage studies were performed on a ceramic composite intended to emulate a dispersion nuclear fuel. The composite is composed of 90-mole% MgO and 10-mole% HfO 2. The as-synthesized composite was found to consist of Mg 2Hf 5O 12 (and some residual HfO 2) particles embedded in an MgO matrix. X-ray diffraction revealed that nearly all of the initial HfO 2 reacted with some MgO to form Mg 2Hf 5O 12 . Ion irradiations were performed using 10 MeV Au 3+ ions at room temperature over a fluence range of 5 × 10 16–5 × 10 20 Au/m 2. Irradiated samples were characterized using both grazing incidence X-ray diffraction (GIXRD) and transmission electron microscopy (TEM), the latter using both selected-area electron diffraction (SAED) and micro-diffraction (μD) on samples prepared in cross-sectional geometry. Both GIXRD and TEM electron diffraction measurements on a specimen irradiated to a fluence of 5 × 10 20 Au/cm 2, revealed that the initial rhombohedral Mg 2Hf 5O 12 phase was transformed into a cubic-Mg 2Hf 5O 12 phase. Finally, it is important to note that at the highest ion fluence used in this investigation (5 × 10 20 Au/m 2), both the MgO matrix and the Mg 2Hf 5O 12 second phase remained crystalline.