A Rutile Chevron Modulation in Delafossite-Like Ga3–xIn3TixO9+x/2

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• 作者：Karl Rickert ; Philippe Boullay ; Sylvie Malo ; Vincent Caignaert ; Kenneth R. Poeppelmeier
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：May 2, 2016
• 年：2016
• 卷：55
• 期：9
• 页码：4403-4409
• 全文大小：448K
• 年卷期：0
• ISSN：1520-510X

文摘

The structure solution of the modulated, delafossite-related, orthorhombic Ga_3–xIn₃Ti_xO_9+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 A_3–xIn₃Ti_xO_9+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 Ga_1.5In₃Ti_1.5O_9.75. 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 Ga_3–xIn₃Ti_xO_9+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.