The relation between the local and the average structure of rhombohedral ferroelectric PbHf 0.9Ti 0.1O 3

Abstract

The local structure of the rhombohedral perovskite PbHf 0.9Ti 0.1O 3 was studied using Pb, Hf and Ti X-ray absorption fine structure (XAFS). XAFS data were analyzed by fitting a parameterized theoretical spectrum to the experimental data. It was found that the structure of the TiO 6 octahedron is very different from the structure of the HfO 6 octahedron. Furthermore, the Pb–O and Pb–Pb bonds have very large Debye–Waller factors indicating that Pb and O atoms are disordered about the rhombohedral positions down to 11 K. Despite the structural disorder, the local structure of PbHf 0.9Ti 0.1O 3 resembles the rhombohedral average structure more than the structure of PbHfO 3 or PbTiO 3. Since PbHf 1− x Ti x O 3 and PbZr 1− x Ti x O 3 have very similar phase diagrams, it is reasonable to assume that the same structural features characterize rhombohedral PbZr 1− x Ti x O 3.