Thermodynamic, structural, and electronic properties of isolated copper and iron

atoms as well as their complexes with O vacancies in tetragonal lead titanate were investigated by means of first principles calculations. Both dopants exhibited a strong chemical driving force for the formation of MTi−VO (M = Cu, Fe) defect associates. The most stable configurations corresponded to a local dipole aligned along the tetragonal axis parallel to the spontaneous polarization. Local spin moments were obtained and the calculated spin densities were considered. The calculations provided a simple explanation for the experimental findings. The results were considered with regard to models for the degradation of ferroelectrics.

Association of Oxygen Vacancies with Impurity Metal Ions in Lead Titanate. P.Erhart, R.A.Eichel, P.Träskelin, K.Albe: Physical Review B, 2007, 76[17], 174116 (12pp)