Lattice distortion and orbital hybridization in NdFeO3-PbTiO3 ferroelectric thin films.

Single-phase xNdFeO3-(1 - x)PbTiO3 thin films with different dopant contents were fabricated on the Pt(111)/Ti/SiO2/Si substrate by a sol-gel route. Grain size was influenced by the dopant content effectively. A synchrotron radiation X-ray diffraction study revealed a reduced tetragonality (c/a) of the PbTiO3 lattice in the films. Distortion of the TiO6 octahedron was weakened, as investigated by Raman scattering and X-ray absorption spectra. An electronic structural study indicated that the hybridizations between O 2p and Pb 6s and Ti 3d orbitals were weakened. The decrease of lattice distortion and orbital hybridization gives rise to degradation of the ferroelectric nature in the films.