title: Mapping chemical disorder and ferroelectric distortions in the double perovskite compound Sr 2-x Gd x MnTiO6 by atomic resolution electron microscopy and spectroscopy.
abstract: In this work we report a study of the chemical and structural order of the double perovskite compound Sr 2-x Gd x MnTiO6 for compositions x=0, 0.25, 0.5, 0.75, and 1. A noticeable disorder at the B-site in the Mn and Ti sublattice is detected at the atomic scale by electron energy-loss spectroscopy for all x values, resulting in Mn-rich and Ti-rich regions. For x ≥ 0.75, the cubic unit cell doubles and lowers its symmetry because of structural rearrangements associated with a giant ferroelectric displacement of the perovskite B-site cation. We discuss this finding in the light of the large electroresistance observed in Sr 2-x Gd x MnTiO6, x ≥ 0.75.
authors.affiliation: 1Departamento de Física Aplicada III & Instituto Pluridisciplinar,Universidad Complutense de Madrid,28040 Madrid,Spain.
authors.forename: Neven
authors.initials: N
authors.lastname: Biškup
authors.affiliation: 3Departamento de Química Inorganica,Universidad Complutense de Madrid,28040 Madrid,Spain.
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Álvarez-Serrano
authors.affiliation: 3Departamento de Química Inorganica,Universidad Complutense de Madrid,28040 Madrid,Spain.
authors.forename: Maria
authors.initials: M
authors.lastname: Veiga
authors.affiliation: 1Departamento de Física Aplicada III & Instituto Pluridisciplinar,Universidad Complutense de Madrid,28040 Madrid,Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Rivera-Calzada
authors.affiliation: 4Instituto de Ciencia de Materiales de Madrid,CSIC,Cantoblanco 28049,Spain.
authors.forename: Mar
authors.initials: M
authors.lastname: Garcia-Hernandez
authors.affiliation: 2Oak Ridge National Laboratory,Oak Ridge,TN 37831,USA.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Pennycook
authors.affiliation: 2Oak Ridge National Laboratory,Oak Ridge,TN 37831,USA.
authors.forename: Maria
authors.initials: M
authors.lastname: Varela