Neutron irradiation effects in perovskite (CaTiO 3)

Specimens of perovskite (CaTiO 3) irradiated with fast neutrons have been examined by X-ray diffraction. Expansion of the unit cell was anisotropic. The volume expansion increased with dose and approached a saturation value of 3.8%. X-ray diffraction lines showed both broadening and attenuation. The attenuation could be explained by postulating random atomic displacements, akin to thermal disorder, having an r.m.s. magnitude of ~ 0.02 nm. Recovery of the lattice parameters takes place in the temperature range 300–900°C, with a spectrum of activation energies. Effective activation energies of 2.52 ± 0.08 and 3.73 ± 0.13 eV were observed during the early and middle stages of recovery.