title: A Rutile Chevron Modulation in Delafossite-Like Ga3-xIn3TixO9+x/2.
abstract: The structure solution of the modulated, delafossite-related, orthorhombic Ga3-xIn3TixO9+x/2 for x = 1.5 is reported here in conjunction with a model describing the modulation as a function of x for the entire system. Previously reported structures in the related A3-xIn3TixO9+x/2 (A = Al, Cr, or Fe) systems use X-ray diffraction to determine that the anion lattice is the source of modulation. Neutron diffraction, with its enhanced sensitivity to light atoms, offers a route to solving the modulation and is used here, in combination with precession electron diffraction tomography (PEDT), to solve the structure of Ga1.5In3Ti1.5O9.75. We construct a model that describes the anion modulation through the formation of rutile chevrons as a function of x. This model accommodates the orthorhombic phase (1.5 ≤ x ≤ 2.1) in the Ga3-xIn3TixO9+x/2 system, which transitions to a biphasic mixture (2.2 ≤ x ≤ 2.3) with a monoclinic, delafossite-related phase (2.4 ≤ x ≤ 2.5). The optical band gaps of this system are determined, and are stable at ∼3.4 eV before a ∼0.4 eV decrease between x = 1.9 and 2.0. After this decrease, stability resumes at ∼3.0 eV. Resistance to oxidation and reduction is also presented.
authors.affiliation: Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States.|Laboratoire de Crystallographie et de Sciences des Matériaux (CRISMAT), UMR 6508 CNRS, ENSICAEN , 6 bd Maréchal Juin, Caen 14050, France.
authors.forename: Karl
authors.initials: K
authors.lastname: Rickert
authors.affiliation: Laboratoire de Crystallographie et de Sciences des Matériaux (CRISMAT), UMR 6508 CNRS, ENSICAEN , 6 bd Maréchal Juin, Caen 14050, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Boullay
authors.affiliation: Laboratoire de Crystallographie et de Sciences des Matériaux (CRISMAT), UMR 6508 CNRS, ENSICAEN , 6 bd Maréchal Juin, Caen 14050, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Malo
authors.affiliation: Laboratoire de Crystallographie et de Sciences des Matériaux (CRISMAT), UMR 6508 CNRS, ENSICAEN , 6 bd Maréchal Juin, Caen 14050, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Caignaert
authors.affiliation: Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Poeppelmeier