Evidence of extended defects in pure zirconia irradiated by swift heavy ions

X-ray diffraction, transmission electron microscopy, and optical spectroscopy were used to investigate the microstructure of polycrystalline samples of pure monoclinic zirconia irradiated by high energy ions. These techniques point out the existence of extended defects and they allow to monitor the tetragonal to monoclinic phase transition as a function of the temperature during isochronal annealings. The Landau theory approach explains the phase transition mechanism via the presence of an important strain field induced by dislocations. Though high and low energy ions can effectively stabilize the same tetragonal phase in the irradiated layer, only point defects are produced at low energy whereas extended defects are also observed at high energy, showing the strong influence of the energy deposition modes on the observed microstructures.