Neutron radiation damage in NbO single crystals

Abstract

Abstract The effect of neutron irradiation and subsequent recovery has been studied for NbO single crystals of a defective NaCl structure containing 25% vacancies of niobium and oxygen. A very large increase (about 1%) in the lattice constant is observed after irradiation of 1.5 × 1019 and 1 × 1020 nvt (> 1 MeV). From the intensity measurements of x-ray and neutron diffraction, it is revealed that the knock-on atoms fill preferentially their respective vacant sites; Mb atoms occupy Nb-vacancies, and O atoms occupy O-vacancies with nearly the same probabilities; 0.53 for 1.5 × 1019 nvt. The mean threshold energy for displacement is estimated to be about 3 eV.