Combined structural refinement and spontaneous polarization study of Bi3.5Ce0.5Ti3O12 by using x-ray and neutron powder diffraction data

Combined structural refinement of Bi3.5Ce0.5Ti3O12 was carried out by using both neutron and x-ray diffraction results based on the monoclinic space group of B1a1. Weighted R-factors were 6.29% and 8.17% for the neutron and x-ray diffraction data, respectively. The goodness-of-fit indicator (S) was 1.9 for all patterns. Lattice parameters were a = 5.4229(6) angstrom, b = 5.4038(6) angstrom and c = 32.8838(5) angstrom. The beta angle was 90.10(1)degrees. Spontaneous polarization (P-s) calculated from the refinement results was 26.7 mu C cm(-2). The contribution of each atom on the spontaneous polarization was plotted and it was clearly shown that the distortion of TiO6 octahedrons was the key factor that determines spontaneous polarization.