Abstract: Ferroelectric and paraelectric states of two-layer supercell PbZr0.5Ti0.5O3 for hydrogen-free and hydrogenated were investigated using first principles density functional theory. We calculated the variation of the total energy with the displacement of Ti along the c axis, the density of states and the Mulliken population between Ti—O, Zr—O and H—O bonds. The results show that the Ti—O and Zr—O bonds of the ferroelectric phase for the hydrogen-free are stronger than those for the hydrogenated and that the strong hybridization between H and O is favorable to form covalent bond between the two atoms. The total energy of the ferroelectric phase for the hydrogenated is higher than that of the paraelectric phase because hydrogen incorporation into the lattice has a direct effect on polarization pinning by possibly forming hydroxyl bond. These data demonstrate that hydrogen introduction during forming gas annealing, hindering phase transition of the PbZr0.5Ti0.5O3 from cubic paraelectric to tetragonal ferroelectric phase, is an important factor causing severe degradation of ferroelectricity in PbZr0.5Ti0.5O3. This study may be helpful to understand the mechanismof severe ferroelectricity degradation for ferroelectric materials during forming gas annealing.

Key words: Forming gas annealing, Ferroelectric phase, PbZr0.5Ti0.5O3, First principles