title: The role of the Pb2+ 6s lone pair in the structure of the double perovskite Pb2ScSbO6.
abstract: The new double perovskite Pb2ScSbO6 was synthesized by standard ceramic procedures; the Rietveld refinement of room temperature neutron powder diffraction data shows that the crystal structure is well defined in the space group Fm3[combining macron]m. It contains a completely ordered array of alternating ScO6 and SbO6 octahedra sharing corners; the PbO12 polyhedra present an off-center displacement of the lead atoms along the [111] direction, due to the electrostatic repulsion between the Pb2+ 6s lone pair and the Pb-O bonds of the cuboctahedron. Dielectric permittivity measurements show a peak near 343 K, with a Curie-Weiss response above this temperature, which suggests an antiferroelectric behavior. Finally we present a DFT study of the electronic structure of Pb2ScSbO6, showing a great difference between the electronic density within SbO6 and ScO6 octahedra.
authors: Area de Química General e Inorgánica, Departamento de Química, Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, 5700 San Luis, Argentina.
authors: Sebastián A
authors: SA
authors: Larrégola
authors: José Antonio
authors: JA
authors: Alonso
authors: José C
authors: JC
authors: Pedregosa
authors: María Jesús
authors: MJ
authors: Martínez-Lope
authors: Miguel
authors: M
authors: Algueró
authors: Víctor
authors: V
authors: De la Peña-O'shea
authors: F
authors: F
authors: Porcher
authors: Francesc
authors: F
authors: Illas