Sr2GaScO5, Sr10Ga6Sc4O25, and SrGa0,75Sc0,25O2,5: a Play in the Octahedra to Tetrahedra Ratio in Oxygen-Deficient Perovskites
Artikel i vetenskaplig tidskrift, 2012

Three different perovskite-related phases were isolated in the SrGa(1-x)Sc(x)O(2.5) system: Sr(2)GaScO(5), Sr(10)Ga(6)Sc(4)O(25), and SrGa(0.75)Sc(0.25)O(2.5), Sr(2)GaScO(5) (x = 0.5) crystallizes in a brownrnillerite-type structure [space group (S.G.) Icmm, a = 5.91048(5) angstrom, b = 15.1594(1) angstrom, and c = 5.70926(4) angstrom] with complete ordering of Sc(3+) and Ga(3+) over octahedral and tetrahedral positions, respectively. The crystal structure of Sr(10)Ga(6)Sc(4)O(25) (x = 0.4) was determined by the Monte Carlo method and refined using a combination of X-ray, neutron, and electron diffraction data [S.G. I4(1)/a, a = 17.517(1) angstrom, c = 32.830(3) angstrom]. It represents a novel type of ordering of the B cations and oxygen vacancies in perovskites. The crystal structure of Sr(10)Ga(6)Sc(4)O(25) can be described as a stacking of eight perovskite layers along the c axis ...[-(Sc/Ga)O(1.6)-SrO(0.8)-(Sc/Ga)O(1.8)-SrO(0.8)-](2 center dot center dot center dot) Similar to Sr(2)GaScO(5), this structure features a complete ordering of the Sc(3+) and Ga(3+) cations over octahedral and tetrahedral positions, respectively, within each layer. A specific feature of the crystal structure of Sr(10)Ga(6)Sc(4)O(25) is that one-third of the tetrahedra have one vertex not connected with other Sc/Ga cations. Further partial replacement of Sc(3+) by Ga(3+) leads to the formation of the cubic perovskite phase SrGa(0.75)Sc(0.25)O(2.5) (x = 0.25) with a = 3.9817(4) angstrom. This compound incorporates water molecules in the structure forming SrGa(0.75)Sc(0.25)O(2.5)center dot xH(2)O hydrate, which exhibits a proton conductivity of similar to 2.0 x 10(-6) S/cm at 673 K.



defect perovskite




oxide-ion conductivity

protonic conduction



doped lasco3


S. V. Chernov

Russian Academy of Sciences

Y. A. Dobrovolsky

Russian Academy of Sciences

S. Y. Istomin

Moscow State University

E. V. Antipov

Moscow State University

J. Grins

Stockholms universitet

G. Svensson

Stockholms universitet

N. V. Tarakina

Julius-Maximilians Universität Würzburg

Universiteit Antwerpen

A. M. Abakumov

Universiteit Antwerpen

G. Van Tendeloo

Universiteit Antwerpen

Sten Eriksson

Chalmers, Kemi- och bioteknik, Oorganisk miljökemi

Seikh Mohammad Habibur Rahman

Chalmers, Kemi- och bioteknik, Oorganisk miljökemi

Inorganic Chemistry

0020-1669 (ISSN) 1520-510X (eISSN)

Vol. 51 2 1094-1103





Mer information

Senast uppdaterat