XAFS study of rhombohedral ferroelectric PbHf_0.9Ti_0.1O₃

The local structure of the rhombohedral perovskite PbHf_0.9Ti_0.1O₃ was studied using Pb and Hf XAFS. XAFS data were analyzed by fitting a parameterized theoretical spectrum to the experimental data using the four nearest coordination shells. It was found that the Ti off center displacement is different from that of Hf. Furthermore, the Pb-O and Pb-Pb bonds have very large Debye Waller factors indicating that Pb and possibly O atoms are disordered about the rhombohedral positions down to 11K. Despite the structural disorder, the local structure of PbHf_0.9Ti_0.1O₃ is closer to the rhombohedral average structure measured by diffraction than to the structure of pure PbHfO₃ or PbTiO₃.