Overlooked cation-ordered brownmillerite in Ba2(In1-xGax)2O5

Octahedral tilting in cation-ordered perovskites--a group-theoretical analysis.

Group-theoretical methods are used to enumerate the structures of ordered perovskites, in which 1:2 and 1:3 ordering of B and B' cations is considered in combination with the ubiquitous BX6 (or B'X6) octahedral tilting. The cation ordering on the B-cation site is described by irreducible representations of the Pm3 m space group of the cubic aristotype: Lambda1 (k = 1/3,1/3,1/3) for the cation o...

Stacking faults and superstructures in a layered brownmillerite

Single crystals of Ca(4)Fe(2)Mn(0.5)Ti(0.5)O(9) have been synthesized using a flux method. The structural characterization using single-crystal X-ray diffraction revealed the space group Amma and unit-cell dimensions of a = 5.3510 (6), b = 26.669 (3), c = 5.4914 (6) Å. The structure is isotypic with Sr(3)NdFe(3)O(9) [Barrier et al. (2005). Chem. Mater. 17, 6619-6623] and exhibits separated brow...

Characterizing Ordered Bi-Ideals in Ordered Γ-Semigroups

The notion of a &Gamma-semigroup was introduced by Sen [8] in 1981. We can see that any semigroup can be considered as a &Gamma-semigroup. The aim of this article is to study the concept of (0-)minimal and max- imal ordered bi-ideals in ordered &Gamma-semigroups, and give some charac- terizations of (0-)minimal and maximal ordered bi-ideals in ordered &Gamma- semigroups analogous to the charact...

Crystal and magnetic structures of the brownmillerite Ca2Cr2O5.

Powder neutron diffraction and magnetic susceptibility measurements at 10-300 K have been used to determine the crystal and magnetic structures of brownmillerite type Ca(2)Cr(2)O(5), which was obtained by reduction of the high pressure phase CaCrO(3) through hard-soft chemistry. The ambient temperature crystal structure of Ca(2)Cr(2)O(5) is refined in space group I2mb and the unusual tetrahedra...

Introducing "One Health" as an Overlooked Concept in Iran