Radiation effects in zircon,hafnon,and thorite: implications for Pu disposal

摘要

Synthetic ZrSiO_4,HfSiO_4,and ThSiO_4 single-crystal specimens were irradiated by 800 keV Kr~+ ions,and the microstructural evolution was observed in-situ in a transmission electron microscope.All three compounds were found to become amorphous up to temperatures in excess of 600 deg C.Using a new model,the activation energies for annealing were found to be in the range of 3.1 to 3.6 eV for these compounds.At temperatures above 600 deg C,the orthosilicates were observed to decompose into the component oxides (e.g., tetragonal ZrO_2 + amorphous SiO_2 in the case of zircon).A single-crystal zircon specimen was also irradiated with a pulsed pricosecond Nd:YAG laser operated at 355 nm,and the resulting microstructure was investigated by optical absorption.SEM.AFM,and TEM techniques.